AstroPhysics Riccardi Honders Astrograph 305mm F3.8 arrives! - Page 5

gregbradley · #81 01-05-2015, 05:42 PM

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 · #82 03-05-2015, 02:15 PM

First light image posted in the deep space forum.

More to follow.

Greg.

gregbradley · #83 05-05-2015, 03:43 PM

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 (Joshua) · #84 05-05-2015, 04:23 PM

Quote:

Originally Posted by 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.

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

Josh

gregbradley · #85 05-05-2015, 06:31 PM

Quote:

Originally Posted by Joshua Bunn

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

Josh

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 (Joshua) · #86 05-05-2015, 06:33 PM

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

gregbradley · #87 05-05-2015, 07:28 PM

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 · #88 06-05-2015, 05:06 PM

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 (Joshua) · #89 06-05-2015, 06:42 PM

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 · #90 06-05-2015, 08:25 PM

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 · #91 15-05-2015, 08:59 AM

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 (Suavi) · #92 15-05-2015, 04:12 PM

Fingers crossed everything works well - happy imaging!

gregbradley · #93 16-05-2015, 06:10 PM

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 (Peter) · #94 16-05-2015, 07:46 PM

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 · #95 17-05-2015, 11:57 AM

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 (Eric) · #96 17-05-2015, 03:29 PM

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 · #97 19-05-2015, 09:53 PM

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 · #98 06-06-2015, 06:11 PM

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 · #99 07-06-2015, 08:39 AM

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 (Chris) · #**100** 07-06-2015, 09:27 AM

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.