AstroPhysics Riccardi Honders Astrograph 305mm F3.8 arrives!

[gregbradley]

My name came up on the Astrophysics Riccardi Honders list and I got notified back in January to verify that I was still interested and there was no guarantee I would actually be given one.

Then 2 weeks ago I was notified one was ready for me. Hence the rapid sale of some very high end scopes I had.

The new scope arrived today and its an amazing piece of engineering. Very solid, heavy but manhandleable (just) with some clever lifting straps.

I hope to have first light soon. I may need some adapters as my Proline + filter wheel + MMOAG looks to be perhaps a fraction past focus or maybe just right on it. Hard to know without setting it up. The SX Trius though may come to focus as the sensor is closer to the top of the camera.

300mm plus F3.8 with this new design is an exciting proposition and should suit my conditions very well (travel to my dark site and 3 nights available usually.

http://www.pbase.com/image/159699738
http://www.pbase.com/gregbradley/image/159699740
http://www.pbase.com/gregbradley/image/159699741
http://www.pbase.com/gregbradley/image/159699752
http://www.pbase.com/gregbradley/image/159699761

Greg.

[niharika]

:party::party:

now lets prepare for some :windy:

[Slawomir]

Great news Greg!

Let's hope winter this year will be dry and cold :)

Looking forward to admiring your new astro-images.

[gregbradley]

Hehehe. It is a bit overcast now you mention it!



Thanks Slawomir. I hope I can do it justice.

Greg.

[DJT]

Awesome! Enjoy:clap:

[gregbradley]

I'm going to have to get a trolley from Bunnings to move it as in its case its pretty heavy. The case is huge as well.

Greg.

[RickS]

Congrats, Greg! When is first light?

[Amaranthus]

Exciting new universe to explore - technically and scientifically. Enjoy Greg!

[gregbradley]

Probably not this weekend but next weekend weather permitting.

I may need some adapters.



It should make it possible to go really deep at times and show up things that my other images haven't been able to.

Greg.

[Hans Tucker]

Stubbier than I thought it was...but nice. So how many years were you on the list before you were notified and offered this scope?

[DJT]

Its like that line in Jaws.."I think we're going to need a bigger boat.."

[Logieberra]

Wow! You lucky duck! Can't wait to see what you can do with her :)

[gregbradley]

About 5 years. I put my name down within hours of the list being created.



:rofl: Yes that's fitting!



Its a her eh? Wow, hope my wife is OK with that!

Greg.

[AG Hybrid]

Congrats. And OMG you live in Sydney. Well that explains why its raining right now.

[strongmanmike]

That's all :)

[SimmoW]

Can't wait to see the first light pics Greg, great looking scope!

I'd call HIM. 'Little Boy' , he reminds me of a small nuke.

[gregbradley]

Yes I think it does explain it!



Cheers Mike, High five back!



:lol:

Greg.

[strongmanmike]

Or Fat Man fits too :P

[gregbradley]

Perhaps the Fat Controller.

Gee I've been watching too many Thomas the Tank Engines with my grandson!

Greg.

[marc4darkskies]

Congrats Greg - very nice addition to the stable! :thumbsup:

[gregbradley]

Thank Marc. There is very little else left in the stable!

Greg.

[Camelopardalis]

Woah awesome Greg, look forward to hearing and seeing more about it :D

[Logieberra]

You a golfer Greg? As chunky as she is, 'Big Betha'?

[Shiraz]

man that looks beautiful. There must be a lot of enjoyment just in owning such well made gear - and you get to use it as well.

Perfect scope for your cameras...particularly looking forward to seeing what it can do on galaxies with small pixels.

[strongmanmike]

If you do name it that, I hope you don't have a stutter (https://www.youtube.com/watch?v=wu6RFApp3CU)

:P

[gregbradley]

Yes it should be very good.



I do play golf sometimes and I do have a driver that is called Big Bertha.
Hmm.



I think it should do quite well. Mike has shown how 300/F3.8 works well with small pixels. I used a Tak BRC250 and a FLI Microline 8300 a lot for galaxies and that worked very well together. That was 250mm and F5 1260mm focal length.



Hehe, that is very funny.

Greg.

[gregbradley]

I just did a test with both of my cameras and they both came to focus on stars using the AP focuser and my imaging setup. I did not expect the Proline to make focus or at least I thought it was close or just going to miss so that is a bonus.

AP focuser 3.5 inch, MMOAG and adapters about 40mm total, FLI filter wheel 4/5 (20mm), FLI Proline 16803 (21.3mm) or SX Trius 694 (17mm).

Still I intend to fit a FLI Atlas as the critical focus zone is small and I could see that using only the microfocuser it would go from in focus to out of focus very quickly.

So it will be adapter to RHA backplate (approx. 40mm), FLI Atlas (31mm), MMOAG (35mm) +adapters (8mm), FLI CFW (20mm), FLI Proline (21.3) or SX Trius (17).

Alternatively:

Adapter RHA backplate to FLI Atlas (8mm) , FLI Atlas (31mm), adapter(4mm), SX AO unit and OAG (74mm), adapter (3mm) FLI CFW (20mm), SX Trius (17) or Proline (21.3mm).

RHA has 162mm of backfocus available from the backplate or 100mm from the AP 3.5 inch focuser (which is a beautifully made focuser with its stainless steel and feathertouch microfocuser).

The FLI Atlas has 10mm of travel so the adapters have to be accurately calculated so the Atlas winds up in focus at around half the travel available.


Greg.

[Andy01]

Guess we can now expect 40 days & nights of flood & rain... Congrats mate, can't wait to see what you produce with that bad boy :)

[Peter Ward]

Welcome to the club.

Heavy sucker isn't it? :)

[gregbradley]

Thanks Andy. I'll try to live up to its capabilities.



Thank you. Yes it sure is. I nearly strained my back the first day!

Greg.

[strongmanmike]

Sure, but I didn't have a beautiful big 17" CDK on a PME at my disposal :eyepop: :shrug: buuuut if i did have both, man, I would probably be using the RHA for the beautiful wide clean 1.8 X 1.8 deg vistas it can deliver (and fast) under dark skies with the 16803 :thumbsup:

Mike

[gregbradley]

Good point Mike.

I think initially it'll be the one I have adapters for first!

What targets would be good at this time? I am thinking maybe a Rho mosaic.

Greg.

[strongmanmike]

Yeah Rho would be good I guess and hey, if it turns out ok, DM has awarded several dozen renditions of it (and Lambda Centaurus) over the years and even two different renditions in the same comp :question:....

Having that sort of field at your disposal gives many options...besides given it is brand new equipment you now have a perfectly legitimate excuse to re-image some of the favourites again :D :thumbsup:

[gregbradley]

Hot tip! Thanks.

Greg.

[Paul Haese]

A nice acquisition Greg. I reckon a rotator in the mix if you can fit it. It's going to make composition easier if you can fit it in the back focus.

[gregbradley]

I don't think there is room unless they are quite thin.

The adapter from the backplate to the focuser is about 45mm.

I can rotate the image train but it does require loosening set screws in the MMOAG.

Greg.

[Eden]

Exciting! Looking forward to seeing the images that you catch with that fine instrument.

Definitely lots of cloud on the way... ;-)

[multiweb]

Whoa! Xmas all over. :thumbsup:

[gregbradley]

There couldn't be any more than there has been though!



Yes, that describes it!

Greg.

[issdaol]

Awesome scope Greg. I have been a big fan of the work you have produced with your prior scopes. I can't wait to see what you achieve with this baby.

[gregbradley]

Thanks Phil! Yes I hope I can live up to the scope's ability.

Greg.

[Tony_]

Beautiful looking equipment - the quality is obvious in these photos. Looking forward to your images Greg (which are already great).

Tony.

[gregbradley]

Thanks Tony.

I was planning on doing something this weekend but the forecast is rain. Perhaps next weekend.

Greg.

[gregbradley]

I received the FLI Atlas focuser for this scope. Now for some adapter calculations and an order off to Precise Parts.

In the meantime I can slum it with Robofocus and an AP bracket for the Robofocus:rofl:

Greg.

[cometcatcher]

Awesome! Just out of curiosity, what's the OTA weigh?

[gregbradley]

Its pretty heavy. About 28kgs. Still manhandleable but I think you need to be careful. It comes with some lifting straps to get it out of the case which are handy. There are a series of photos done by Roland showing how to mount the scope into the rings on a mount. That helps.

I guess some of the weight comes from the need to have everything strong and rigid and no flex. Like a Tak. My AP refractor was also very solid and semi heavy but in a good way (quite handleable).

Put it this way, its the only scope where I am totally confident there is no chance of focuser flex as the drawtube is thick stainless steel. Not aluminium but stainless steel. It not only looks good its extremely strong.
I'm surprised more high end scopes don't use that.

Greg.

[cometcatcher]

Thanks. Probably an easy one to lift for Mike! Not so much for me lol. Not that I'm thinking of getting one. Just curious.

[gregbradley]

Yeah Mike probably would only use one hand! Its not a lightweight instrument but manhandleable with some care.

Greg.

[gregbradley]

I am hoping to do a first light this week. Forecast looks hopeful for late in the week at my dark site - woohoo! Now if only the replacement chain link for my filter wheel would arrive before then!

Greg.

[rustigsmed]

Fingers crossed Greg! must be exciting ... of course its been pretty bad in Melbourne for about a week before new moon and will be for(atleast) another...

Looking forward to seeing first light :thumbsup: all you need to do is narrow down on which target you want :)

[gregbradley]

Thanks Russell. This next week is ideal moonwise for imaging so I plan on an LRGB image or perhaps an LRGB with some Ha.

Probably a galaxy as well to see how it goes on that. It all depends on how many nights. Usually my dark site can be clear when Sydney is cloudy and rainy but not necessarily at the moment.

Any suggestions for targets? Proline 16803 and RHA is about 1.7 arc minutes x 1.7. So Rho Ophiuchi as a mosaic may work.
M17, Omega Centauri (quick image of a few hours) maybe another Eta C (I'm a bit Eta C'ed out though). Last ditch Orion before it sets.
Vela SNR is still up. Herschels Ray could be nice NGC 2736 especially with the Trius with its high QE in Ha and O111. CG4 could be interesting although perhaps a bit of a vague target for first light.

Galaxies NGC3521, 3621, 2997 are in good positions. Leo triplet of galaxies, Sombrero Galaxy, Antenna Galaxies, Centaurus A (then I'd never hear the end of it from Mike if it didn't show the extended halo - so that's a risky one to do!).. The Queen of Galaxies NGC6744 is rising now and is a viable target although quite dim and really needs massive exposure so risky with dodgy weather forecast.

The Running Chicken Nebula is well positioned. The Blue Horsehead IC 4592 is a possible. Its near Rho Ophiuchi. NGC3576 is in a good position.

NGC6188 is rising and could be a target for the 2nd half of the night.

Any suggestions?

Greg.

[clive milne]

Please God,
let it be something more original than the 56,784th rendering of eta Carina.

[gregbradley]

:rofl: Don't worry Clive I am Eta C'd out.

Greg.

[Peter Ward]

WHAT? And not stick with the program? Heresy!! :)

[clive milne]

Well... you know where I am coming from,
I envy you and look forward to what you come up with.

best
c

[strongmanmike]

That's quite a list already Greg...don't think you need any help at all :thumbsup:

You are right about one thing though, you will never be able to match the Olsen-Sidonio Centaurus A Extreme Deep Field (http://www.pbase.com/strongmanmike2002/image/150610685/original)...no waaay Jose'! with a limiting mag around 25 thaaaat will sit at the top for ever, never to be beaten, uh uh, so why bother :shrug: :D.....so in other words, there ya go, take up the challenge Bradley, make that $ outlay count ;)

Mike

[Peter Ward]

So....Greg....now we really need to talk about this Sydney weather.....

[gregbradley]

Hehehehe, hmmm, Cent A may've just shot to the top of the list! Although looking at your collaborative image again its really an exquisite image and likely to be a benchmark for a long time - like the 15 minute barrier in the Men's 1500mm freestyle lasted.

Greg.

[gregbradley]

Yes, I feel a bit guilty about that.:lol: (not)

Greg.

[SpaceNoob]

Looks like you've got a big Low pressure system down south with your name on it heading north to Vic lol.... :lol:

[strongmanmike]

Yeah, but it took two of us...you have the equipment to do it all by yourself ;)

You must be pretty excited to get it onto something, anything! ...we all wait with bated breath :)

Mike

[gregbradley]

Just an update. I have started imaging with the Honders even though I am waiting on a couple of adapters so I can fit a FLI Atlas focuser to the imaging train.

I managed to mount it fine but its a bit of a struggle being a solidly built scope. After I got it all set and started to home the mount the penny dropped - oh, the scope is facing the wrong way. Oh no.

So I had to take it off, turn the saddle around and remount it with more grunt and puff.

Balance was no real problem.

Even though the scope has a feathertouch microfocuser and its a superbly made AP focuser with stainless steel drawtube this scope is extremely precise and focuses in a very small critical focus zone. Manual focus is somewhat challenging and I am only getting it quite close but not perfect. Hence the Atlas that is about to be used. I can see this as being a necessity on this scope. It certainly snaps to focus though - wow, getting sharper, sharper and then the graph tends to suddenly spike. The microfocuser does not really have tiny enough shifts to optimise that but that's the Atlas focuser's job once fitted.

The scope has some nice touches such as removable back plates to air the primary mirror and help with cooldown. Also the dewshield is extremely well made with a clever system of attaching. The inside of the scope plus the inside of the dewshield is flocked with a very high quality flocking and incredibly neatly done.

No sign of any large halos around bright stars so far that I have seen in some Honders images. I notice there is a flange about 5mm high around the end of the secondary mirror shroud. It sticks outwards. No doubt that would help. So not sure if I will encounter them on super bright star scenes like Horsehead or if Roland has modified the scope to suppress haloing. It seems baffling is often an area scopes are worked on after they have been around for a while.

Dew does not seem to be an issue and the thermal blankets it comes with work well. There has been some slight dewing on the corrector plate though first thing in the morning but nothing showed in any images so I assume it must have been after dawn. I intend to use some dew straps though (never used them before).

The scope seems also very sensitive to CCD squareness. The little tilt tip adapter on the SX Trius camera was a bit off from my last use and it showed heavily in the focusing images. I fixed that mostly but still a tad more adjustment required. It seems somewhat unforgiving of that.

The Proline was happy though with good stars.

12 inch F3.8 has the main advantage of a bright image fast. Wow, subs look very bright and detailed in a fraction of the normal time.
I'd estimate this scope is 3X times faster than my refractors and about 1.5 times faster than a fast Tak BRC250 F5 I used to use.
Its not far from my CDK17 at F4.5 (hard to compare slightly light polluted sites to my dark site where everything looks better).

Focus does not appear to shift appreciably over the course of the night. I will be implementing autofocus periodically but comparing star sizes over a 4 hour period they did not seem to change too much that would not be accounted for beyond going lower in the sky.

This scope will be incredible at narrowband imaging. A 20 minute 1x1 Ha image (new 5nm Ha filter) of a dim LMC neb was really bright.

The PMX is handling the scope but I think a new Tpoint model is needed as this scope with gear on it is nudging 30kgs +. Some autoguiding is not as good as what I was getting last with the AP140. Tweaking the Polar Alignment is needed as there is some drift between subs. I am not sure if TPoint is more accurate than Pempro polar alignment.

I will be able to post an image shortly I hope.

I'll take some photos of the scope on the mount and post them later as well.

Greg.

[Slawomir]

Thank you Greg for keeping us informed.

A very interesting read and your experience surely goes against what some people might think- that if you get a high end gear everything is super easy. I feel that quality gear helps to elevate experience and skills to new impossible before levels :)

Looking forward to further updates and to seeing your new astro-photos.

[RobF]

Yep, some photos would be nice to drool over.
Sounds like pure astro-porn :thumbsup:

[PRejto]

Hi Greg,

Interesting read! I think you absolutely need a new T-Point model for this scope and equipment. But, be sure to save your old model to re-use with the AP140. All you need to do is a short recalibration into the old model and you are good to go. The old model certainly contains a lot of terms that would be completely wrong with the new scope.

Peter

(PS Thanks for the package!)

[DavidTrap]

Somehow I doubt Rick will be giving him back the AP140! Hehe

DT

[RickS]

It would need some very large aperture inducement ;)

[marc4darkskies]

What? Through the clouds and rain you mean?! :help:

Look forward to seeing the pics Greg! :thumbsup:

[gregbradley]

Its a precision instrument for sure and requires precision handling. I am starting to get used to it now. I have imaged over three days now with it. I was surprised at how easily I picked it up and put it back in its case. Getting it out of the car though - wow.



Coming up shortly.



Thanks for the lend. Yes a new T-point model for sure is needed.
Now I have to figure out why T-point wouldn't link images. It was before. Oh well. more problems to solve!



Thanks for reminding me. I only stopped crying about it yesterday!!!



You will be hooked on AP after using it.

Greg.

[gregbradley]

No they are only around Kurrajong and Gross Vale! You go over the mountains and often its clear skies!

My dark site the last several trips has been crystal clear and Sydney was overcast with rain threatening.

Greg.

[gregbradley]

A few pics.

The scope is actually white, the black is a thermal blanket to prevent dewing.

One photo there shows the primary mirror backplates removed to speed cooldown time.

Its a heavy scope. Roland posted photos about how to mount it. I am glad he did.

It didn't seem too bad lifting off the mount and back in its box. But getting the box out of the car or into the car is quite an effort.

At the outer limit of what you would call portable. Very solidly built which seems to be an AP characteristic.

Greg.

[Slawomir]

Awesome gear Greg.

[Joshua Bunn]

Loving the updates Greg, Such a beauty of a scope! Out of interest, are you using the top clamp/dovetail screw on that versa plate or just the bottom 2?

[gregbradley]

It looks the part doesn't it.




The bottom 2. The top 1 I screw all the way in to prevent a slip out. I noticed the knob has a hexagonal hole in the centre so you can tighten using Allen keys. So I did. A nice feature to make sure everything is snug.

Greg.

[Joshua Bunn]

How will it slip out the top? unless you point bellow the horizon (maybe working on the focuser? I would like to suggest, your pointing will be better if you use all 3 screws, I'm sure of that. I noticed less movement of my full length dovetail on my scope when i used all 4 plungers on the ME as opposed to just 3. Just had to add some weight to the versa plate at the front to get the Dec to balance.

Josh

[Logieberra]

Can the versa plate can be unscrewed from Dec axis and moved down a few inches to achieve what Joshua suggests?

Silly Q. What is that fancy black sock on the scope? Your invention, or part of the kit?

[gregbradley]

Good tip. I 'll look at shifting that around. I think I got that wrong, it was the bottom knob that screwed in. Pointing wasn't too bad - a bit off. Not a problem with the Proline as its a large FOV. With the Trius it was a bit off with its smaller FOV. Autoguiding though wasn't so great which surprised me as the last I used the mount with the AP140 it was spectacularly good. The heavier load is showing up its not perfect. I think the Polar Alignment needs to be tweaked. Balance was perfect. It had been raining recently so perhaps its shifted a tad. I noticed drift between subs so the PA is out a little.

Also the scope requires the camera to be very very square otherwise you get some odd shaped stars in the corners. My tilt tip adapter on the Trius was off.

Precise focus is another thing that I wasn't able to achieve manually although I got it pretty close. I am sure it can get closer with the Atlas focuser. It really is quite a small critical focus zone. Its the fastest scope I have ever used (F5 Tak BRC and my CDK 17 with reducer is F4.5 are the 2nd fastest).

I should look up exactly what a Riccardi Honders is. It looks a lot like an SCT with a corrector but its more than that with a different shaped corrector plate and mirrors with a corrector lens of some type. The mirror coating is on the underside of the primary mirror glass which is very unusual. I guess it can't get dirty or degrade there.

Greg.

[gregbradley]

Its a thermal blanket to prevent dewing. Its supposed to work well. It seems to. It comes with the scope from AP.

Its like wetsuit material with a Velcro strip at the overlap. It would be easy to make one for another scope.

Greg.

[RobF]

Wow. Seeing the big FLI filter wheel against it really emphasises the size of the beast. Thanks for sharing some pics Greg. Work of art :cool:

[gregbradley]

It feels like its the work of a perfectionist who has a real passion for scope making. It is fairly large but almost half of that is the dew shield and without that its quite stubby!

Greg.

[gregbradley]

Got the Precise Parts adapter to replace the focuser today. An impressive adapter but then it cost $500 - ouch.

Just waiting on a FLI adapter now that is on its way to attach the MMOAG to the FLI Atlas focuser.

I hope to change over the the filter wheel to a 7 position filter wheel soon. I don't want to swap filters over all the time to do NB and it lets dust in etc and requiring fresh flats all the time.

Later I add the AO unit to the Trius imaging train to get the maximum out of these sharp optics. My dark site has pretty good seeing most of the time and even when its bad its still imageable.

Greg.

[gregbradley]

First light image posted in the deep space forum.

More to follow.

Greg.

[gregbradley]

Final adapter and a replacement chain spare part for the filter wheel arrived today. That means I should be able to focus with FLI Atlas and FocusMax now.

Greg.

[Joshua Bunn]

Great! Do you use TSX Greg? If so, why dont you use @focus2?

Josh

[gregbradley]

I could. I started a thread about this a while ago and consensus was FocusMax was the best focusing software.

Do you use @focus2?

Greg.

[Joshua Bunn]

I do Greg. I use TSX exclusively and have found @focus2 to be reliable for me.

[gregbradley]

Good to know.

Its a plus to have everything in the one software package. Sky X is a nicer software package now its had some time to mature.

Greg.

[gregbradley]

Oops one of the adapters doesn't fit into the one I thought it would. Another adapter required for the MMOAG to fit together with the Atlas focuser.

More money and time!

I repaired my filter wheel successfully so that's one thing out of the way.

Greg.

[Joshua Bunn]

Ahhh! That's a let down for you Greg, I bet you're itching to point your new gear at the skies with all the parts working.

[gregbradley]

Yes it was a bit of a bummer. But hopefully the part arrives next week before I take it back to my dark site. Ordered a dewbuster with temperature sensors and a dew-not 16 inch dew heater. Not so much to stop the optics dewing for imaging but around dawn when a bit of dew formed on the optics and to prevent dew stains on the optics which may be hard to clean as its enclosed.

I am thinking this scope may be an awesome mosaic scope. 12 inch F3.8 probably means a good SNR on a 1.5 hour LRGB image so I could get 6 to 8 panels done in a few days using the Proline 16803. I also got some brass shiming material from a steel supplier to pack out the Proline and get it 100% square with the Honders. I think there may have been flex in the filter wheel which was missing 2 screws now corrected. I think everything has to be perfect to match this scope's optics. F3.8 is a hard task master.

Greg.

[gregbradley]

The final adapter arrived yesterday and it all goes together. So now there's the nervous moment to find out if it comes to focus like that!

I'm off to take advantage of a good weather forecast and do some imaging with it.

Hopefully I'll have some images to post next week.

Greg.

[Slawomir]

Fingers crossed everything works well - happy imaging!

[gregbradley]

I'm down at my dark site and I received the final adapter Thurs
Time to try it out
Got it all set up
Start to focus uhooh pretty large out of focus star donuts
I suddenly lose confidence .If it doesnt come to focus it means another $500 adapter
I worked out the spacing several times before I ordered the $500 Precise Parts adapter.
I see the Atlas has most of the travel available
Move move move I think is going to make it
Then it seems not phew gone past focus so backup and bang perfect focus with 2.5mm to spareno .- no sweat!
Checked it out last night with proline
Perfect round stars to 4 corners and very tight looking
I take an image and now I am getting excited with the potential of this scope. The image looks like a 12 inch APO refractor
I also put another dovetail on the top of the rings to stiffen up the mounting. Round stars in the images
I set it up to do a run excited by the quality of the first subs and I get up at 3 to do flip and the scope is dewed over
No worries I expected that as I removed the dew shield because it was windy.I dont have dew heaters yet
But the autoguider disconnected after I walked out of the observatory grrrr so I've changed the usb cable
I also extended the observatory walls to make a wind break and am hoping for better productivity tonight!
This scope is looking mighty fine
Greg

[PRejto]

Hi Greg,

Glad you just made focus with 2.5 mm to spare!

I think the question you need to ask is whether 2.5 mm is enough room for FM to work? I know at F7 I'd need more room. I guess at f3.8 things would be more compressed. I think FM likes to take a bunch of images at HFD = 10 and then move to focus. My version of FMV4 does that on both sides of focus so hopefully you easily get to HFD=10 or 12 before running out of room. If not perhaps you can tell FM only to move in to focus.

Re @focus, I've never tried it but others claim it works quite well and is a lot faster than FM.

Peter

[gregbradley]

The Atlas only has 10mm of travel
and the scope with that camera is in focus at 78690 out of 105000 available
I can pack it out to make it focus at 50,000 or perhaps even more
If needed
It is more compressed as you say where it will go in and out of focus very rapidly compared to other scopes I've used.
You'd think 105000 focus steps was over the top but you can see a slight difference in stars with only 10 steps difference.
I did quite a bit of imaging lady night with the dewshield on and no dew all night. Ha exposes quite fast and is very detailed
A 10min 1x1 5nm Ha is like a 20min on a slower scope
Greg

[ericwbenson]

The slope of the focus vs position is related to the inverse square of the focal ratio. Hence halving the focal ratio (f/7 to f/3.5) and you have a slope that is four times steeper, and FocusMax needs 4x less distance to do V-curves and run it's algorithm. From my experience with an ~f/7 scope, a f/3.5 would need about +/-1 mm of travel for FMax to function.

Analogously, the good old CFZ (critical focus zone) is also simply related to focal ratio. i.e. CFZ (µm) = 2.7 * f.r.^2
hence why f/3.5 scope are a PITA to focus, relatively.
So for Greg's scope the traditional CFZ is ~40µm

However I find the NCFZ to be more useful for specific situations since it takes into account the seeing at the site, the focal length and how much defocus you are willing to tolerate, see here:
http://www.goldastro.com/goldfocus/ncfz.php
for the formula.

Best,
EB

[gregbradley]

Thanks for that Eric. That certainly matches what I have experienced so far.

The scope is actually quite easy to focus as when you hit focus here is a definite snap to focus and the graph rises steeply.

Also I notice the focus is very stable despite temp shifts. It does not appear to move much if at all despite no carbon fibre. Roland mentions that in the writeup on the scope that focus does not shift much with temperature. That is handy.

The FLI Atlas focuser is a gem of an accessory. Heavy, expensive but wonderfully accurate, strong and stable.

Greg.

[gregbradley]

Just an update.

I moved the Versaplate of the PMX mount forward so that all 3 tightening knobs hold the scope. That made a difference.

I added more counterweights as I was using a shaft extension and I think it was impacting on guiding accuracy. I noticed an immediate improvement so that was a helpful thread here on Ice in Space. The counterweights are now further up the shaft with none on the shaft extension so as to reduce moment arm inertia.

I have now mounted the RHA on a portable pier which is inside my home observatory along with my CDK17.

I managed to redo the Polar Alignment and got TPoint working again (I had checked a box that said to use all sky image link - apparently that was all that was stopping it from working - that represents 5 hours of mucking around).

I did the quick polar alignment routine in the PMX manual. Then I did a couple of 35 point TPoint super models and did the adjustments to gain polar alignment. Then I notice this new button from the latest Daily Build of the The Sky X - more accurate polar alignment - why not? It gets me to slew to a star low in the south or north and then manually adjust the mount until the star is in the cross hairs of the image. Wow, I had adjust the mount quite a bit and I am thinking , great I am wrecking the polar alignment I just spent an hour achieving. I test with some autoguiding - wow - round stars!

OK. A meridian flip and some odd looking stars. I try a different guide star and recalibrate. Still odd. I turn off Protrack - round again. OK the Protrack 35 point model is not good enough. I got 4 hours of imaging done which was surprisingly productive for setting it all up.

I also received a Dew Buster controller and Dew Not 14 inch dew strap.
I noticed some minor dew on the corrector plate after a night's imaging. Not bad though. The dew strap goes on tonight and I got a 5 amp power supply to run it.

12 inch F3.8 when it is setup properly is really nice to image with. A bright solid image is formed very rapidly.

I plan to add an AO unit to the Trius setup on the Honders next.
Planning it out. 165mm is the actual backfocus of my current setup
(Precise Parts Adapter 39mm> FLI Atlas 31.75mm> adapters 5mm> MMOAG 40mm > Adapter 3mm > FLI CW 4/5 20mm > FLI Proline 16803 21.3mm using Astrodon Gen 2 filters.

Greg.

[gregbradley]

I did a large 250 point T-Point model last night and implemented the polar alignment mount adjustments (relatively minor sadjustments and I had just done 2 hours of imaging with quite round stars not perfect but good. Then I got eggy stars - what????

Used Pempro's polar alignment wizard and it had me adjusting the mount a LOT. What????

Stars were better but not perfect yet.

What a hobby!!

Imaging with this scope is awesome though. 3 hours at 60% QE of the Proline or 77% of the Trius just creates an image so quickly. It must take
1/3rd of the time a 5.5 or 7.5 inch scope at F7.5 takes.

A Tak BRC250 F5 I had for a while was also quite fast. This is faster again. I think 4-6 hours would be good for many objects and 6-12 fo galaxies would be plenty. That equates to probably 20 hours at F8 100mm aperture or 30+ hours for galaxies. Or 20 hours at F7 140mm.

Greg.

[SpaceNoob]

Hi Greg,

I had a similar issue recently, somehow my PEC got all wacky and threw out my subs. I used the wizard in theskyX to refine my polar alignment and now it sais my error is 0" and 0" to the refracted pole. New PEC run via pempro showed no drift from polar misalignment, the new PEC resulted in +/- 0.2" corrected. I now have perfect tracking again. I'm assuming the constant nights of -6 here have probably contributed to whatever suddenly threw off the usual perfect performance I get from my mount. 30minute guide logs are a flat line and I had a few subs with 1.3" FWHM at 2.5m focal length.

[PRejto]

Hi Greg,

I think it is a mistake to expect that T-Point and PEMpro drift alignment are going to "agree" very much on where to place your PA! There has been endless and heated discussion about this on the SB forum. If I have digested the discussion properly T-Point is making a mathematical construct of all the pointing combined with flexure issues of every setup and offers various PA recommendations based on what one desires to do. But, PEMpro offers great PA at just one sky location. (Dec=0, etc) So, it seems all PA Is a compromise. Patrick W. has said (perhaps reluctantly) that using drift alignment is good enough as long as one also uses T-Point to model the sky so that Protrack can do its thing. But, so is T-Point PA!! Of course, if you moved the polar axis when you ran PEMpro drift you've got to recalibrate into your large model to get it to work again! The recommendation is to recalibrate as a "portable mount." The other possible reason your new T-Point model didn't work so well is that maybe your polar axis moves, especially MA, might have not been as accurate as you thought. There has been much discussion about that as well and now are methods to move using fiducial stars to confirm accurate adjustments. So, you re calibrated after you made moves of PA?

Peter

[gregbradley]

What are fiducial stars? Fixed stars?

I did use the accurate polar alignment once and it did work reasonably well.

I was getting round stars and then I noticed my mount needed more setup - the bolt on tripod legs bolts were not all tight and the mount plate needed a shorter bolt etc. Plus after that it needed to be relevelled.

I did more last night. I used T-Point again and got it close but not round stars. I did another 105 point model and got the report saying to do a very large lowering of the altitude. It wasn't right. I wonder if this tripod pier has some flex in it still. Not all bolts are as tight as they could be.

Yes I redo a full model once I change PA adjustments in PA.

I did the Pempro drift again. That got me reasonably round stars. Not good enough long term but good enough for one night.

The thing I like about Pempro is that drift is actually measuring the thing you want to eradicate directly rather than indirectly with Pempro. I have had great results with Pempro before though. As a contractor I always want the actual measurement over the planned or ought to be measurement. It saves a lot of errors from off assumptions.

Greg.

[PRejto]

Yes, but not to be pedantic. PEMpro drift alignment gives a great result for just that one area of the sky. Image in a completely different area and you may find that drift is much worse. Of course, a good model + PEMpro is going to correct that through Protrack. At least that is my take after reading endless discussions on the subject (of which I tend to agree with Patrick a bit more than Ray G)

Peter

PS My understanding of a "fiducial star" is just a star at a position in space such that if you mechanically move the mount to centre on it will in one step account for calculated errors in ME and MA.

[gregbradley]

Thanks Peter. Makes sense on the definition. Fiducial mean fixed.

I did another 200 point model tonight. I implemented the accurate polar alignment actions. I realised when I did it before I first had done the ajustments from the Polar Alignment report first then the accurate polar alignment adjustments plus I was not careful enough about centring the star in the image.

But tonight I did it very precisely and one axis was perfect the other was still off. With Protrack tracking adjustments activated it helped but still you could see it was fighting drift. So I did a quick Pempro polar alignment wizard and indeed the Azimuth was perfect but the altitude was a it off. A couple of quick adjustments and it was spot on and now very round stars (not perfect but then its poorish seeing) with protrack on.

I am seeing some spikes though. I hope that is the seeing and not some dirt or fraying belts in the mount. But round stars I am happy so both tools were helpful here.

Plus it pays to carefully read the instructions! (accurate polar alignment instructions).

Time will tell if that drift is corrected generally or only for one patch of the sky but to be honest I have never noticed any mount to guide well in one patch and not another. Usually better when the scope is pointed near the zenith.

Greg.

[SpaceNoob]

Spend 30 minutes clearing your PEC, collecting, applying, and verifying a new one with PEMPro... I did this recently after my PME and PMX performance suddenly degraded when we had 2 weeks of -6 and below. I am assuming you're re-greasing routinely as is advised too?

[gregbradley]

Hi Chris,

Yes the PMX often sounds like it needs extra grease. I haven't yet though. Its not that old really and lightly used. But yes I have the grease. Is there a video or tutorial on how to grease it?

My place does not go below about 4C and the last time I used it I got round stars at my dark site.

I did some more T-Point and autoguiding massaging last night and am getting round stars now. They could be a bit better but they are acceptable.

I'll do another large T-point run and perhaps a fresh PEC. Can't hurt.
I find Pempro a very nice piece of software. Very bug free and easy to use. Hat's off to Ray Gralak for making such a reliable piece of software. That's a standout.

I'm also thinking of replacing the belts as a lot changed their belts over to the newer grey ones from the original black ones.

The dew heater works well. The optics have been dew free in the morning now since I installed it.

I am familiar with dew heaters. It seems fairly warm like an electric blanket. I have it turned down to a really low level and have the strap under the thermal blanket. It has a sensor but its warm all the time. Is that normal?

I am noticing that this scope does show up bad guiding more than others. I think that's because its F.8 and a star off centre even for only a short time records a fairly bright spot so errors show up in the image more. Of course the plus side is the stars when done well really look good.

Greg.

[SpaceNoob]

Hi Greg,

There is a link for the PMEII/MX/MX+:
https://youtu.be/qe11z6sQzz4

For the PME:
https://youtu.be/yl2mqN0py08

I would perform this every 12months for low use, or 6months for high use. Then follow up with a new PEC run. I do 6monthly just because of the variance in conditions here.

They're good mounts, but like anything moving, it needs a service to be running at optimum. If your polar alignment is bang on, which I suspect it is, its worth at least just checking your PEC is correct by checking it with Pempro. I do around 5 cycles, any seeing issues should process out anyway. Assuming its all good, you should have corrected PEC within an arc second. Mine is around +/- 0.2" and +/- 0.3" for the PME and PMX respectively, with PEC applied.

Here in Canberra I've found that I really need to maintain my PEC seasonally, my dome completely freezes up, ice everywhere. I started by chasing my tail thinking that my polar alignment had somehow slipped, so I used PEMPRO wizard to refine it.... end result was horrible and off significantly. I went back to TPOINT polar alignment, synch east near home, small calibration runs to the east to refine it to 0/0 using the wizard and my camera, then do a large 200-300 point run, but the tracking issue was still evident. I performed a new PE collection with Pempro, applied it, and boom... Mount is perfect again.

Hope you can isolate the issue soon and have everything running at optimum.

Cheers,

Chris.

[gregbradley]

Thanks for that Chris you have been most helpful.

Greg.

[gregbradley]

Just another little update.

I managed to get round stars last night from the PMX so it is capable of handling the RHA with care. The scope was slightly off balance and I rebalanced it plus I did a new PEC curve, tightened all the adapters and fittings and did a new 100point t-point model which basically said its good enough. The T-point model errors were quite low. I did one before the rebalance and tighten and got terrible t-point model errors.

So now the only tweak needed now seems to be getting the camera perfectly square which I did this morning. If there is even slight tilt it shows up in the corners quickly as elongated stars. Usually only one or two corners not all 4 or one side is sharp and the other a bit out of focus.

F3.8 is a hard taskmaster but worth it for the speed. But for sure once I've got it all perfect its gonna be a case of don't touch anything!

Its an interesting journey as there are now quite a few scopes that are F4 or faster on the market and the faster they are the fussier they will be to tune. So the speed comes with a demand for accuracy in all things around it. No free lunch here. Luckily this scope does not need collimation as that would be a challenge.

Greg.

[gregbradley]

I am close now. Almost perfectly round stars to all corners. There is still a slight amount of tilt. Its a matter of working out the spacers and making sure the Proline is seated flat against the filter wheel.

Gee the images look nice when its all aligned. Really nice.

Greg.

[gregbradley]

Did some imaging last night. Tried some more spacers - it got worse. Reverted, beautiful images.

For the sake of perfection a tiny shim has been added and I'll do a really large T-Point model tonight if its clear. Its now awfully close and the images are drool quality. This scope is magic when everything is setup for it.

I do notice I get slightly better tracking when the scope is on the West side. What's with that?

Greg.

[Joshua Bunn]

It's magic when it's all going well, hey Greg.
Maybe your setup is counterweight heavy, the worm lifting the gear? Not that I think it's any difference on a Paramount...

Josh

[PRejto]

More of a thought bubble than anything else, but assuming perfect balance weight wise on each side the only difference would be a considerably different moment due to the scope length from east side to west side. But, why that might matter is not at all clear to me except possibly to note that on one side the larger moment is being lifted, the other lowering. I wonder what you might see if you turned off declination guiding? Any difference from side to side when the only corrections are in RA?

Peter

[gregbradley]

Ah yes that might explain it. With the OTA on the west with it pointing to the east the counterweights are being lifted (I have make it slightly imbalanced to the east to prevent oscillations) and when OTA is on the east and the counterweight is lowering and the imbalance is causing it to press down very slightly but in the opposite direction. Maybe slight backlash?? It was only a slight difference. Both gave round stars, but on OTA on the east looking west gave slightly rounder stars.

Greg.




It was a very slight difference Josh so its probably more to do with some slight flex in something or tiny backlash.

Greg.

[gregbradley]

Yet another workout tonight. I tried the .5 min and 2 maximum move in autoguiding per the CCDware min/max move calculator. I also did accurate polar alignment from the last T-Point model ( a very small adjustment to the mount). I also corrected a bit of flex between the camera and the filterwheel when the scope was pointing directly up. Bang round stars. Awesome.

A tiny bit off in one corner at a full 1x1 image of a 16803 camera (4 screens wide) is good enough. I think that will even disappear when I switch to a new filter wheel soon (the existing was slightly modified at one point by me and not 100% square now but normally its not noticeable).

The smallest flex causes corner stars to go off. Apparently also slight PA errors but mostly flex. So the camera has to be well seated and no flexing.

So now I leave it alone! Don't touch anything! I think I will even walk past it very slowly. Its enough to make you superstitious.

But boy when its all perfect the images it downloads are breathtaking. I've used lots of high end scopes and this one is the best.

Greg.

[Atmos]

Glad to hear that you're finally getting closer to "officially" starting your imaging runs :)

[Joshua Bunn]

Good stuff Greg!



What did you do to correct the flexing?



How long are your integrations?

Josh

[gregbradley]

:rofl:I know! Hilarious really how much work goes into setting up a precision instrument.

[QUOTE=Joshua Bunn;1184244]Good stuff Greg!



What did you do to correct the flexing?

I put some 1.5mm blue plastic spacers (the type used in construction you get from Bunnings) at each of the 4 corners. Then I pushed the camera in hard whilst I locked off the filter wheel. There is still a tiny flex that I expect to handle fully when a new 7 position filter wheel arrives. But at this stage its not worth chasing as I think I will go backward. Its like contracting. Sometimes there is a point on a job if go beyond you start going backwards! Knowing when to stop is important sometimes.


How long are your integrations? At the moment 5 minutes but I think now longer should not be a problem. It came over cloudy as I was testing so next clear night I will test, 10, 15, 20 minutes. I might also do a "quick" 300 point T-Point model.

That new accurate polar alignment feature in T-Point is pretty cool The model said good enough but in the adjustment section it said to lower the axis by 1.3 tics. The accurate polar alignment though made me raise it about 2.5 tics. I then got even rounder stars. How about that.

I may play with the refine curve feature of Pempro but last time I managed to get the refined curve uploaded when I had just done the 2nd curve data with the PEC turned on but not the next day trying to load a saved curve. Pempro is a bit awkward sometimes. Its not clear how to load and save things and reload. It seems more oriented to playing back the curve in real time but that would mean turning on that program everytime you wanted to image. Unless I am misunderstanding it.

My current curve is 5th order and the RMS value dropped a fair bit. Last time I used just the linear curve and the refined curve was adding the 2 curves. I am getting better results with the new curve than the older refined curve.

Greg.

[Joshua Bunn]

Are you saying you are finding this setup more susceptible to polar alignment errors than your other scopes?
I would have though it to be hard to find PA drift errors in 5 min exposures and at 1.17m FL, considering how close to the pole you are.

One other thing Greg, are you seeing flexure in your image train or tilt?

Josh

[gregbradley]

Good point Josh. It was probably just the better guiding.
Its tilt and its not much now. I can see a tiny flex between the camera and the filter wheel. About to be remedied with a new filter wheel.

Guiding now and roundness of stars is very good.

Greg.

[gregbradley]

I did a calculation of my imaging train weights and was surprised.
I am at 39kgs which is the limit of the PMX.

I'd say its doing pretty well considering.

OTA 26.2kgs
dewshield 3.2kgs
rings 2.2kgs
Proline 2.5kgs
Filter wheel 2kgs
Atlas focuser 1.36kgs
Adapters .4kgs
thermal blanket and dew heater .3kgs
cables, plugs .4kgs
Astrophysics 6 inch dovetail plate 1.9kgs
Losmandy D dovetail plate (on top of the rings) approx. 1.4kgs

Up around 42.3kgs. It adds up fast.

Greg.

[glend]

Greg the PMX specs suggest 90lbs (or 40.90 kg) as the payload but make no distinction between visual and imaging payloads - which some mount manufacturers do specify. If you use 2/3 rds as imaging capacity that would take you down to 27kg, or 31kg at 3/4 capacity. So are the PMX numbers always listed as the imaging capacity?

Are you looking to reduce that load or your happy with it as is? What makes the dew shield so heavy, is it metal and an accessory to the OTA? I'd think you could get rid of at least 2kg on the front by going to a foam type dew shield. I use a piece of black marine carpet as my dew shield and it probably weighs less than 0.5kg for sure. Weight reduction is good for most scopes if it pushs you away from mount imaging limits.

[gregbradley]

I just realised there were 2 other heavy parts, a 16 inch dovetail plate and a inch Losmandy one. So that makes it over 42.3kgs.

The PMX is doing pretty but this explains why I am having everything to be perfect and there is no leeway. So I think that 40kg figure is the absolute max and that I am overloaded. I get round stars when everything is perfect.

I plan to upgrade the mount as you mention 2/3rd capacity is probably a good approach. The Honders is a very solid scope which is great for F3.8 but its heavy.

Anyone interested in a perfect PMX that is freshly regreased and a perfect PEMPRo PEC curved entered into it? I've had it about 3 years and it got the replacement worm which is around 1 to 1.4 arc second after PEC.
The best guiding I have ever achieved was with this mount with an AP140 and FLI Proline and MMOAG STi guiding. Also with a TEC180 both fairly large and heavy scopes and imaging trains but not as heavy as the Honders. Plus all the software - TPoint, Camera add on, Sky X Pro serious, Precision PE (I prefer Pempro though and the PEMPRO curve is already loaded into the mount).

http://www.pbase.com/gregbradley/image/159562180

Greg.

[gregbradley]

An update if you've been following this. It is interesting to chronicle the sort of process you go through with new gear even if its high end.

I now have sorted the PMX mount and its giving round stars. I have checked 5 and 10 minute exposures and there is no reason to believe it won't do 30 minutes now.

I took some advice from here and looked for weight savings. I took the counterweight shaft extension off as it wasn't being used. That was quite heavy so I estimate about 2.5kgs or so. I took the thermal blankets off (only about .4kgs). I think I'll put them back on as I noticed some slight dew on the corrector lens this morning despite the dewheater.

I removed the top Losmany dovetail on put on the top of the rings. It wasn't actually adding rigidity like I thought and that must be another 1.5 kgs or so.

I tightened the cam pin and replaced the little socket screw with a better one and I tightened the worm pressure screws 1/4 turn. I don't think this did anything but thought I would tweak it a tad.

Mainly I got a proper T-Point model and sorted through the current error in the Polar Alignment report Sky X Build 8906. It reverses the instructions for the ME adjustment (Altitude adjustment). So its better to use the advanced polar alignment adjustment. This time also I slewed to a much lower northern star and the report gave it 99.1% ideal rating.
I did several T-point runs of about 30 points then a 300 point model of which 58 failed so it was 242 points.

I used 2 x 2 binning and very short exposures to centre the bright star for maximum accuracy.

Polar alignment now seems spot on.

I used .5 min and 2 maximum move for autoguiding settings, direct guide.

3 seconds subexposures with an SBIG STi (just bought a 2nd one for the Planewave, great little guiders) on a MMOAG and second delay to let the mount settle between corrections. I was getting a spurious PE until I used second delay. So not sure what that was but its gone.

Mount is very slightly balanced towards the ground so there is slight pressure on the belts.

Next is cable tidy up. I have replaced one power cable to the RHA back fan with a lead to the PMX power outlet. I've ordered some 12 volt splitter cables so power can come from the PMX to all accessories and not a lead with a splitter cable feeding everything.

The result is very good tracking and round stars and the super sharpness of the scope is allowed to shine.

Greg.

[gregbradley]

A new FLI 7 position filter wheel for 50mm square filters arrived. Much better the way it attaches to the Proline. 2 bolts go through the Proline to lock it in place to the filter wheel. Plus it sits dead flush with the camera. There is no way it can tilt. Its a tad heavier (600grams) but its all 7 filters (so sick of changing narrowband filters) and a good system for mounting the filters. The face has a deeper well so the adapters make thread does not have to be so short. All in all a nice unit.

Tonight will show but I am optimistic that any tilt issues are history.

The imaging train from the filter wheel back feels sturdier and more rigid.

Greg.

[Paul Haese]

Photo's?

[SpaceNoob]

I think that's what come with mine last week. Bolts directly onto the PL16803, no flex observed. I had to adjust the Pyxis 3" rotator's delay settings to boost the torque a bit.

[gregbradley]

Yes that's the one, FLI CFE 5/7. A nicely made unit. It seems to vignette a bit less as well. I think the opening is a bit wider than the CFW4/5.

The bolt on is a big improvement. Expensive for a filter wheel though eh?

Greg.

[SpaceNoob]

A blip compared to the camera and 50mm LRGB/Ha/SII/OIII Astrodon's.... Our $$ certainly isn't where it was.....

[gregbradley]

True.

One thing I noticed today after using it for the first time last night. Generally speaking, with an image train like this that has several dovetail connectors with grub screws that lock it in place, I think its better to put it together on a bench then mount it on the scope rather than add things whilst part is on the scope. It opens the door to tilt. I think these dovetails will lock in slightly out of whack.


I think also its good practice to tighten the grub screws to slightly tight first one, then diagonally opposite to slightly tight then the next 2 then snug up to final tightness in the same way.

I am wondering if a little bit of Teflon grease on these dovetail fittings is not a good idea so they can slide into the final lock position and not grab in some slightly skew position.

Greg.

[strongmanmike]

Ooooh squeeeel :cheers: that looks bwudiful, look out imaging world here comes Chris :thumbsup:..hmmm? have to come over sometime and drink beer..I mean check out your gear (I always get the word gear and beer mixed up for some reason :shrug: )

Mike

[SpaceNoob]

Yeah, I put everything I could together on a bench, I even took off my focuser. The whole train effectively. I got my partner to help me bolt it on to the back of the CDK. She's a tradies daughter, comes in handy when things need fixing or telescope gear needs to be setup with assistance :lol:

I usually apply pressure against the two connecting components and lightly screw in the bolts until they bite a little. Then tighten them a bit each until they're all tight and nothing tilts out. With a rotator in the mix, everything needs to be perfect.

[gregbradley]

Good approach Chris.

I am wondering though if a bit of Teflon grease smear would also help them seat well. I would be worried though it could make stuff slip but I a smear would prevent the aluminium dovetails from grabbing before they are well seated.

I noticed I had one corner with distorted stars the other night and I was shimming out the camera to correct. It was difficult. So yesterday I took them off and reseated them on the bench and last night it appears to be round stars in all corners so something was off a tad.

Also I found the MMOAG eyepiece holder tends to hit against the CFW so I had to grind off a section so that it clears it. I think it might have been pushing the CFW out a little bit causing the distortion. Does your MMOAG hit your CFW 5/7? We have essentially the same setup here with the exception you have a rotator. Otherwise its exactly the same. Great minds eh?

Greg.

[SpaceNoob]

Ok, my MMOAG only impacts with the CFW at certain angles, rotating it to 0 degrees (relative to the shortest edge of the CFW) with say +/- 5 or so degrees, there is no impact. Mine is a Monster-MOAG, not sure if you're using a Mega-MOAG or an older version. This one is a few weeks old, so would be a recent run I guess. It's very slim but sturdy, and no visible vignetting issues outside of the spec of what I'm expecting to see on the CDK itself.

[gregbradley]

I'm using the Monster MOAG as well and it hasn't changed since it came out although I notice Astrodon now have a 2 or 4 port version for guide cameras in different orientations. Not sure what for. Perhaps you could run 2 autoguiders at once or just for more guide stars?

Mine was just clipping the CFW almost imperceptibly and I only noticed it because I was hunting for what was pushing one corner of the camera.

MMOAG is a great accessory and has served me well for several years.

Greg.

[gregbradley]

Another chapter is unfolding with this scope. I bought Raki's AP1600GTO to mount the Honders as the PMX as good and smooth as it is was at or bit past its capacity. Following the principle of overmounting your scope I thought it was appropriate. I could have gotten another PME but wanted to try AP as anything AP I have had has always performed the best of anything.

Also a lot of RHA owners use AP1600's I found out.

I am in the process of modifying my pier (almost finished) to hold it and also to upgrade the bolts to larger sizes so its really rigid. I may end up going permanent pier rather than this fairly solid but portable pier I have from Mountain Instruments.

The AP1600 can handle 100kgs of load. It also field upgradable to super accurate encoders which gives less than .2 arc sec tracking and eliminate PE.

I may end up getting those at some point in the future when the Aussie dollar recovers (what - say 2020???).

I drove to Melbourne and Lakes Entrance to deliver my trusty PMX to Erik and pick up the AP1600 from Raki. Over 3000kms later it is at home.

So it will be 2 separate systems, the CDK on a PME and the RHA on an AP1600 both able to run at the same time with 2 different computers so I can get maximum imaging time done and probably do several combined images. PL16803 on the CDK and something smaller on the RHA perhaps an 8300 camera. That gives a similar FOV to each other and matches the pixel to focal lengths well.

By the way if anyone wants to buy an AP RHA there is one up for auction on Astromart. I think this is the 2nd one I have seen for sale since AP started making them 3 or 4 years ago, so its rare.

Also Rolands personal AP175 refractor. You can bet that is a beauty.

Greg

[Joshua Bunn]

Exciting times for you Greg.
How about mounting the RHA on the PME and the CDK on the AP 1600 as this would suit the carrying capacities of the mounts better?

Josh

[gregbradley]

Yes it is Josh. I mainly want to make sure I am getting the full sharpness the AP optics have to offer.

I think carrying capacities are similar. The PME 2 capacity is 105kgs but I suspect SB exaggerate their carrying capacity a tad.

I like the idea of like with like (AP with AP) besides the PME handles the CDK17 easily.

Greg.

[PRejto]

Greg, you are like a dog with a bone! Once an idea gets planted you certainly see it through quickly. I'm sure that AP mount will be great! I wonder if you will miss the ability to just home to get going?

Good luck!!

Peter

[gregbradley]

Yes I definitely am :rofl:

Home position is definitely useful. You can do home with the encoders or if you get a home sensor fitted. But from users accounts once its setup its not really an issue.

At least I hope so.

Greg.

[niharika]

You will be in an excellent position to do a what you like and what you don't between ME & AP. I only ever lost position when I synced wrongly, but then again it was just in my backyard :D and I could just run and correct it.

[gregbradley]

Thanks Raki,

It will be in my backyard as well so no problem there.

Greg.

[gregbradley]

The Honders likes the AP1600.:lol: Its giving nice round stars now that could stand a slight improvement still. So tonight if its clear I plan to do a monster 400+ Tpoint model and implement the accurate polar alignment adjustments! A 16 inch saddle that is on the way may also help in case there is a little bit of flexure there. The guide errors seem very low a lot of the time.

One feature that seems a standout on the AP1600 mount is the way the gears and worm engage. On other mounts they are permanently engaged. The AP1600 gears and worms seem to only engage when its tracking. Clever. The axes are stiff but you can push them with a small amount of effort. Fine balancing is not regarded as that important per the manual.

Its also dead quiet when tracking. When slewing at 600X its not that loud either. At 1200X its louder but not outrageous. It does sound like the motors have plenty of grunt which is reassuring. There is no movement in either axis when you give it a slight push. No wiggle, nothing. Amazing. The whole unit comes across as ruggedly accurate and precise.

Its also able to be upgraded at home with absolute encoders which get rid of PE altogether and gives below .2 arc sec guiding and unguided tracking for many objects. This gives you back the home position which is probably one of the best Software Bisque features of their mounts. Some time in the future I'll probably get those.

Greg.

[Logieberra]

Greg, there are sets of little black clutch knobs on the RA and Dec. Yours must be very loose, or finger tight only? For heavier loads, AP recommends that you tool tighten - but not excessively.

AP also have plans for homing-limit switches on the 1600. It's a kit that you bolt on. A fraction of the price of the encoders, but still giving those homing and safety stop features that we love on the SB mounts. See the 3600 page - they've been out for a while on that mount.

Logan.

[gregbradley]

Hi Logan,

Are you supposed to tighten those clutches when tracking? I thought they were there only for loading/unloading the mount. I'll check that out. I just read the manual on this point. Wow, Duh. Read the manual eh? I'll tighten them now!

I'll look at that kit for the 3600 to get an idea of these homing switches.

Thanks,

Greg.

[Logieberra]

All good Greg. Glad to hear you're so happy with the AP :)

Attached, 3600GTO limit/homing brochure. We can expect something similar for the 1600GTO.

[gregbradley]

Thanks Logan.

Sounds a bit more involved than I thought. It may be better to bite the bullet and simply get the absolute encoders. Also needs the special APCCA software. I know there is APCC available not sure about the APCCA version.

Greg.

[gregbradley]

I got some feedback from Roland on a couple of questions. I discovered that I had set my autoguiding settings wrong. At least for this mount.

I was using .5 minimum move and 2.0 or 3.0 maximum move. I was lowering it to the default .01 minimum and that seemed to work better. But tightening the maximum move should ignore moves not needed.

The 0.5 min/2.0 maximum came from the CCDWare autoguiding calculator but that is for direct guide which is a Software Bisque way of controlling the mount from autoguider corrections. AP uses Pulse guiding or relays. I can't quite tell if pulse guiding is the same as Direct Guide but I think its very similar. Both do not need an autoguider cable.

Roland said to use .01 to .03 for minimum move and .3 to .5 maximum move depending on the focal length ( I assume by that he uses .3 for the longer focal lengths?). .01 minimum move for good seeing, .03 for less good seeing.

2 to 8 second guide exposures, aggressiveness 6 to 10 with 6 in poor seeing and 10 for good seeing.

Callibrate at celestial equator. Reverse commands with meridian flip.

Backlash settings to zero. Guide frame size 16 x 16 to minimise cosmic ray hits.

I just fitted an AP 16 inch saddle to the AP1600 to hold the Honders more firmly as it has 3 tightening points and is super well made.

I am redoing TPoint models and Polar Alignment. 400 point Tpoint model in progress.

As a tip, I think its faster to use Pempro's polar alignment wizard to get PA very close rather than a series of TPoint models. Then use Tpoint to do a 35 point model and do the accurate polar alignment routine. Then a large Tpoint model and do the accurate polar alignment routine. I think that's about as accurate as it can be.

I am also going to experiment and see if I can track with no autoguiding and Protrack only and get round stars at 5 and 10 minute exposures.

Update: I did the 403 point Tpoint model Accurate Polar Alignment (a very small tweak so PA is essentially perfect). I tried a 5 minute exposure Protrack only - not too bad but somewhat elongated stars. With autoguiding - perfect. Packing out the camera to get rid of tilt. One corner seems in, weird. A tip if you do this. The image on the screen corresponds to the same corners of the camera looking at the camera from the back. So top left of screen is top left of camera looking at it from its back. That can save you a lot of time figuring that out!

Some of the lowest guide errors I've ever gotten. Up there with the PMX and AP140 a few months ago. 3 second guide exposures. 0.1 minimum move, .3 maximum move, aggressiveness 4, Pulse guiding in Sky X running the autoguider.

Greg.

[PRejto]

Hi Greg,

How much do you dither between subs? I found out the hard way that if I have too small a max move + too low aggression it takes forever to correct the dither. I might be wrong but I just increased my max move a lot to take care of this. Doing so didn't seem to effect guiding at all as normally I don't get any really large moves to worry about except for the dither.

Anyway, generally I wonder about how large a move you and others set for dither. Is larger generally better, or is 1 pix enough?

I also came to the conclusion a while back that using PEMPro for drift alignment is pretty quick and then I followed by running T-Point. However, with the new APA routine I'm not sure that is still the case. PA using T-Point is not an iterative process though many assume that it is or just end up using it as such. Again, according to Patrick one large model followed by PA should be do the trick. Using the older method (non-APA) ended up being iterative only because the tic marks let the process down. With APA the tic marks are just a "guide." I used to calculate my own PA corrections and then confirm the moves photographically...similar to APA but much harder to do especially in azimuth.

Peter

[gregbradley]

I suppose theoretically one large TPoint model is enough but I found APA on a 33 point model was off by a large margin. Iterative Tpoints at 33 points each got it close then a large Tpoint model AP seemed to get it very close.

The 403 point model PA is essentially perfect. I don't know what SB are talking about saying Protrack can do unguided imaging. It certainly can't.

Greg.

[strongmanmike]

I set my dither move in Astroart5 camera control to 2 pix, this seems to work well with the NJP mount and minimises time lost for reacquiring of the guide star, which can vary anywhere from almost instantly to as much as 30sec, depending on the seeing and direction the dither move took the scope :)

Mike

[gregbradley]

I haven't been dithering as usually there has been a bot of drift between subs anyway. At the moment perhaps there is no drift. I don't see dithering as an option in Sky X autoguider control. I thought I saw it there a few months ago.

Greg.

[Joshua Bunn]

Hi Greg, It's in the take Series tab... :thumbsup:

[gregbradley]

Thanks Josh.

I knew I had seen it there somewhere.

I had Sky X recognising my FLI CFW 4/5. Now I am using FLI CFW 5/7 it does not list it as a choice. So I have to work out whats with that first.

I intend to start using Sky X camera control for all imaging soon. I like the fact you can program more than 4 filters for an imaging run (CCDSoft only allowed 4) and this dither which I have not used before except for a short time I used a dither plug in for CCDSoft which had a bug in it as it crippled subframing which I used for autoguiding.

Peter, I see it has a delay exposure feature and a settle threshold so these could solve your problem if you are using Sky X for camera control.

Greg.

[PRejto]

Oh, I'm not saying I have a problem. I use the delay and the settle threshold so that works fine. I was mostly curious if there is a "science" to setting the dither amount? 2 pix does sound reasonable and 5 a lot. But why 5?

Greg, there are numerous examples of fantastic unguided images throughout the forum at SB. I think it really depends on a lot of factors, but the refractor people seem to nail it pretty well. I've done 6 min subs with no problem but compared to others that's nothing.

Peter

[gregbradley]

Thanks Peter.

I looked at the sub I did with Protrack only again and its not that bad. Not good enough but not bad.

I imagine short focal length light scopes may have a better chance. It probably comes down more to the mount than Protrack.

The good news is the AP1600 is performing brilliantly and round perfect stars are now common. I am getting some slight flexure of the camera at the filter wheel junction to adapters. I've packed out the camera with some spark plug gap feeler gauge pieces (they worked better than brass shim for some reason). So when the camera is pointing down I am getting really good stars to the corners but at lesser angles I am not sure I get them 100% of the time. I may turn the filter wheel around so the end is sticking up in the air and make sure all its cover plate screws are tight. The other solution would be to ditch the MMOAG and use a solid adapter from the focuser to the filter wheel (it may not change anything though if its the filter wheel that is flexing) and use a Baader Vario finder with AP support bracket attached to the scope body for guiding. Some use that and find it works. Its a clever mounting system that holds the guide scope rigid. It looks to be the gold standard for guide scopes.

http://www.astro-physics.com/

Greg.

[gregbradley]

Here are some photos of the setup I took this morning:

http://www.pbase.com/image/161014757 AP RHA on an AP1600 on a Mountain Instruments portable pier (about to be changed for a permanent pier) and the CDK17 on a PME and a Pegasus pier in the background.

http://www.pbase.com/gregbradley/image/161014758 The AP RHA AP1600GTO and Portable pier.

Greg.

[Somnium]

i am unbelievably jealous of your scopes and mounts. it is set ups like this that makes me want to double my budget ...

[gregbradley]

They are pretty setups I must say. I think the last year's images on this site though have shown very clearly that superb results can be achieved with much more modest gear these days.

Greg.

[gregbradley]

Last night I was doing another night of imaging with the Honders (working beautifully) and I could see the object would be too low after about 12am. So I thought I would go at 11:30 cut the run short a tad and swap over cameras to the Trius and image a galaxy for another 4 or 5 hours from 12 to 5am. Should only take 30 minutes tops to swap the camera.

Well 4.5 hours later it was running well! A dodgy USB cable, minor mistakes, focusing, getting the camera square, rebalancing.

Got about 2 hours on a galaxy though.

The moral of the story is a setup that is all running perfectly is deceptive and gives the feeling that changing out to some other part will be a piece of cake. Think again.

Greg.