CDK17 on a Paramount ME and Pegasus Pier

[gregbradley]

I installed my Planewave CDK17 and Paramount ME mount today.

Rally gave me some helpful advice. It needs more counterweights believe it or not so I will sorting that out next:

http://upload.pbase.com/gregbradley/image/127500517/large

Here is a fairly recent photo of my observatory:


http://www.pbase.com/gregbradley/image/125486267


Here is a shot of the gorgeous TEC fluorite 180mm triplet"


http://www.pbase.com/image/127500629

I also got a Tak 4 inch reducer to work on my TEC using Precise Part adapters. I am using it now. It gives F5.25 at 180mm APO quality.

I would not be surprised if this is the only one in the world. I am not aware of anyone else imaging at F5.25 with 180mm APO aperture.

Its like Takahashi finally made a 180mm FSQ!

Greg.

[DavidU]

What a fantastic setup you have there. That 180mm is a beaut.

[Alchemy]

Pretty incredible setup. Right out there that's for sure

[Peter Ward]

Looks great!

Extra counterweights are always useful eg:

http://www.atscope.com.au/BRO/pme_scope.jpg :)

[jase]

Greg

What happened with the through mount cabling? :shrug: That is one of the pleasures of the PME (aside from the feature rich MKS4000 TCS I should add). No more tangled cables! You'll probably have to dismount the CDK17 to sort it out, but its worth it! ;)

Great set up. Images of equipment is one thing...images of celestial objects through the equipment is another... :) "Show me the money!"

Cheers

[renormalised]

That is one great setup!!!:)

[rally]

Greg,

Good to see you are on the way, won't be long before you have a 100 point model and that thing will be singing !
BTW - you might like to tune the slewing acceleration rates down a tad too.

Just an afterthought - can you remove the C/weight safety stop and extend the weights all down another cm or two to reach balance if you are so close ?

Jase,

Give the Guy a break :)
It only went on this afternoon !

Cheers

Rally

[jase]

:D Yeah I shouldn't talk! Mine is still sitting in boxes on the lounge room floor. :rolleyes: I'll get my act together soon!

[Moon]

Greg,
Great to see you the scope up on the mount at last. I'm looking forward to seeing some CDK images in the not too distant future.
Have you decided to start with The SkyX or version 6?
James

[Bassnut]

Looking very smick Greg.

[Octane]

That's so hot right now.

Do want.

H

[gregbradley]

Thanks for the replies, it is very exciting. It is a very solid looking focuser
and the whole appearance looks very well made.

And oh my god all the adapters fit and I don't need any! There's a first for everything.:lol:

Greg
.



I think there may be a small amount of room. But it is a fair bit out of balance. I suspect its more than one counterweight's worth.

Thanks for your advice today, that was very helpful.

I'll be using The Sky V6. What are the advantages of the Sky X?

The shot is just everything put together today. There are some cables already through the mount like a USB cable for the camera. The Proline has a built in usb and power hub so it will handle the autoguider and filterwheel.

That just leaves the scope 12V supply and a USB cable.

I need to organise more counterweights before I can image with the CDK.

Greg.

[Doomsayer]

Should be a killer combo.
I'd recommend AAG tpoint mapper for automating your mapping with Tpoint. It is very easy to use and it is free! It requires CCDsoft or Maxim plus Pinpoint for platesolving. It really is a joy to watch the PME running an automated 100 or 200 point model.

guy

[Bassnut]

Yes, Guys right, AAG tpoint automapper is joy to use (with sky 6).

A significant advantage of the PME is the huge range of software available to make it really sing, and save LOTS of time getting it really, really smick, night after night, its worth the time investigating.

Ive been trying out Sky X lately, its very good. If you havent got pinpoint yet (and BTW did you get Tpoint with the PME?), then consider Sky X before you spend any more money and learning curve time on software (incl Sky 6).

[Moon]

+1 vote for AAG Tpoint Mapper (You'll need it for the polar alignment.)
James

[Bassnut]

Yes, specially for polar alignment, its by far the quickest way, arcsec accurracy within 15 mins all up incl stuffing around (20 points, 10 sec exposures bin3, 2 or 3 adjustment/runs), tells you exactly how many knob tweaks required, insane.

[gregbradley]

Thanks for that recommendation. I'll download that.







I have Tpoint, Orchestrate, Precision PE, Sky 6.




Sounds good.



I like the sound of that.

Thanks for all the help it makes life a lot easier with the learning curve.

Greg.

[Bassnut]

Well, if you have Tpoint and Sky 6 already, then get pinpoint/AAG Tpoint mapper and use DL and yr set.

Gaud I get so confused, spend time susing it out greg, there are soooo many choices with the PME, but use em, its worth it.

[gregbradley]

Thanks Fred.

I downloaded AAG T mapper.

Pinpoint is a Maxim product. Perhaps for later.

Greg.

[Doomsayer]

Pinpoint - the full version - is needed for AAG tpoint mapper to work.
DC-3 Dreams, the people that also supply ACP observatory control software, sell it. I don't use Maxim, but I think Maxim only has a light version of Pinpoint built in.

guy

[strongmanmike]

Super dupper looking outfits there greg :thumbsup:

Just curious Greg, you are 100% an astroimager right?...so this usually means pointing to and staying on just one or maybe two targets a night so why all the worry about Tpoint and syncing perfectly with TheSky etc etc :shrug:. What's wrong with just pointing to within the native out of box few arc mins, composing your frame shot and off you go, don't need any more than EQ6 or Meade capabilities for that :shrug:

The high quality native tracking of teh PME coupled with normal autopguiding is as perfect as you need too, all this extra capability all seems a bit of overkill :question:

Maybe I am missing something? :)

Mike

[DavidTrap]

I can see where you're comng from Mike - I have been a little disappointed by the GOTO accuracy of my AP mount vs my Meade LX90, but it is adequate for imaging.

However, wouldn't accurate pointing make mosaic composition easier? I'm a long way from that - just did my first combination of a long and short exposure image tonight though!

DT

[gregbradley]

Initially pehaps but apart from the capacity of the PME I want PEC and errors under 1 arc sec. Accurate go-tos are also important at long focal length.

If I have any problem with Tpoint I will just drift align and see how she looks. Then add the bells and whistles as go along, PEC mainly.

I got the mount counterweights solved today (weights from a gym shop and some magnetic tape to reduce the hole size. It was close to being in balance with the 3 counterweights as it turned out.

I got the mount at the right angle and installed the driver got it working on my computer. I got the Planewave focuser and temperature control working as well. The usual difficulties in doing the above with new equipment but I am ready to image now. If tomorrow night is clear then I should be up and running. The Starlight Express Lodestar in installed but it needs a special autoguiding cable it did not come with grrrr.

So the ST402 may do that work whilst waiting for the cable.

All systems go now.

The PME is quite user friendly so far.

Greg.



Alt Az is easier to do accurate go-toos. With my NJP mount I found polar alignment the key thing for accurate go-tos. If go-tos wee off it was mainl polar alignment was not accurate enough.

Greg.

[Moon]

Mike,

You can plate solve and sync like you said during an imaging run, but it can cause problems, especially near the meridian. If the mount gets confused and thinks it's on the other side (or hemisphere) it is a pain to fix it up. This can happen if you have flipped to the west, and then plate solved, then re-slewed to the target and then plate solved again and this last slew has in fact taken you to the east side without a flip. With TPoint you are doing the same thing (i.e. plate solve / syncing) but its all done in advance.
So when you do a meridian flip - the target is always dead nuts in the right spot. I always leave my camera at 180 degrees, so the images register perfectly, but I can now see why camera rotators are so popular.

There are other advantages too, but the meridian flip is the main reason I use it.

James

[gregbradley]

Thanks Jams.

Greg.

[Bassnut]

Mike

Sub arcminuite pointing and calibrated/auto composition nudging with a random camera angle (with a rotator) become important over 2m FL.

Yes, all the extras are a pain, but only need setting up just once on a permanent rig. I havent needed to sync even once in over a year now after the initial set up, pointing is always within arc/secs from power up. And one click "point here" for compostion on a constantly changing camera angle saves a huge amount of time compared to hand nudging with the directions confusingly changing every night (cam angle).

I used to spend up to 30min every night syncing/searching for objects just out of view and hand nudging on the G11 at 3m FL. I can get the whole obs powered up and imaging/focused/guiding within 10mins with the PME now.

Polar align to arc/secs takes 10mins tops with Tpoint/pinoint/AAG auto too, much faster than drift align, so tempting to do more often, to make sure its bang on (I found polar align drifts over a period of 2 mths or so 5-15 arcsecs depending on the weather, the pier must be moveing a bit).

Add up say 20min reduced time each night over a year, and the time saving is substantial.

[DavidTrap]

The more I use the AP mount, the more I realise what you say is true. The Meade system also uses "modelling" (I think), which is lacking from the AP controller.

DT

[Moon]

Greg
Did you see today's APOD (http://apod.nasa.gov/apod/ap100819.html)taken with a CDK17 by Tony Hallas (http://astrophoto.com/Pelican.htm)??
You need to get that scope all fired up!
James

[Bassnut]

What do mean by "modelling", PEC or pointing?. Either can be done via pempro or Tpoint/sky. AP is an excellent mount, seems a shame not to use these tools.

[DavidTrap]

My understanding (and this may well be wrong) is that many mounts use "modelling" to improve pointing accuracy by compensating for slight inaccuracies in polar alignment, measured during the "alignment sequence". It's nothing like what Tpoint does, but it helps.

There are many posts on the AP Yahoo Group that mention the lack of modelling in the AP controller. It may be added to revisions of the firmware...

I'm very happy with the AP mount, it's accuracy is fine for my current imaging demands - at Duckadang, the objects were always within the camera's field of view (DSLR at 600mm focal length) - but I'll have to learn what to do as I try to work at longer focal lengths.

DT

[Bassnut]

Well, on a quick look, Sky X includes AP mounts. Tpoint/pinpoint pointing modeling is done entirely within Sky. Given the cost of the AP, it would seem a small investment to get those tools. Geez cheap skate, get with the cool gear :P :thumbsup:.

[ericwbenson]

TheSky6 + TPoint will make an AP mount (or Gemini or MI500 or anything else controlled by TheSky) point like a PME, so to speak. The all-sky modeling is a software implementation that takes catalog/user coordinates, corrects them via the TPoint model and sends the mount the "fixed up" coords.

The Gemini controller actually also does the same thing for the Losmandy mounts, except the model is simpler, only about 7 terms, but it works really well. The multi-star alignment routines offered by Meade and Celestron AFAIK only correct a few terms (polar offsets, cone angle and flip backlash IIRC).

What only the PME (well, actually any MKS4000 controlled mount with TheSky+TPoint) can do is Protrack, where the fixed-up corrections are sent in real time and the mount tracks out polar error, tube flexure, gear eccentricity, counterweight bar deflection, etc. Those who don't want to spring for TPoint (250USD)can get MaxPoint (150UD), it does about the same thing, but not the Protrack part.

The only other mount out there, that I know of, that can do something like Protrack is the PWI Ascension 200, they use a Sidereal Technology controller (which does the real time correction, software on the PC does the model). The ASA mounts in theory could do the same thing, but I don't see it advertised anywhere, do they have software for them?
Straying a off-topic a little...What I find interesting is that ASA direct drive mounts state on their webpage that plate solving/adaptive optics are no longer necessary with the hires encoders. But no encoders can deal with things like tube flexure or axis non-orthogonality, a bit of advertising bluster perhaps...

EB

[gregbradley]

Yeah I like it. If I posted an image like that here I'd get a caning
for oversaturation. The colours are a bit over the top but that is his style.

Yep, I'm getting there. Started doing test images tonight.
I did a drift alignment and was getting round stars 2 minutes
unguided which I thought was impressive given the long focal length.


I am not sure I have the correct autoguiding cable for the PME.
I think its just a standard SBIG ST4 style cable.

When I try to move in focus mode in CCDSoft there is no movement but I can move using the joystick to centre the object.

I'll try to autoguide next session with it.

Greg.

[DavidTrap]

Thanks Fred!

I do have SkyXSAE, but no Tpoint. The pointing accuracy of my portable setup suits my current needs, but it's good to know it can be improved in due course!

Thanks also to Eric for a thorough explanation of what the modelling does on various mounts.

(Probably should let this thread return to its original topic - Sorry Greg)

DT

[Doomsayer]

If you are using CCDsoft to control the guide camera you should use 'direct guide' for autoguiding with the PME - this is in the advanced settings for autoguiding - no cable required - commands are sent through to the mount directly.

guy

[gregbradley]

Hi Guy,

That sounds good.

So I don't need a special cable for my guide cam just the images from the guide cam then direct guide through the Sky and CCDsoft.

Where is the menu for chosing direct guide? Is it in the Sky 6 or in CCDsoft?

Thanks for the tip - I like the sound of that.

Greg.

[Doomsayer]

It's in the CCDsoft camera control window, in the Autoguider settings section - I think the default is 'camera 'relays', No RJ12 from the camera to the mount is required with the PME whe using direct guide. A good feature in CCDsoft.

[gregbradley]

Thanks very much Guy. I found that and it is now working. Thank you!

What does Pro Track do and how do I access it?
Per the Bisque website it sounds like it improves trakcing accuracy.

Also I bought this PME second hand. I am wondering if Precision PE PEC curves are saved in the flash memory of the mount or if the program has to be running to get the PEC affecting the tracking?

Greg.

[Moon]

Greg
If the previous owner did the PEC, then it will be saved in the flash memory in the mount and you can use it no problem.
I attached a screen print of mine so you can see what it should look like.
(The Sky->Telescope->Options->More settings->PEC)
Of course to be safe you could always record it again when you get a suitable night.
James

[Doomsayer]

PEC is stored in the mount. The memory may have a PEC model loaded already. You can use Precision PEC (yet more additional SB software) or PEM PRO or equivalent to record the PE in CCDsoft, import to PrecisionPEC, process it and then upload it to the mount. Precision PEC is pretty basic but is tailor made for the PME, Sky and CCDsoft. To use Protrack you need a really big Tpoint model - 200 points or much greater (which is where automated mapping comes in handy) - and you need to have the right terms added to your miodel (as well as good alignment). It has taken me quite a while to get the hang of the terms in Tpoint, but I wouldn't describe myself as an expert. From there you can activate Protrack in TheSky. If set up optimally, the PME should be able to track unguided for 10 minutes I'd guess with the 17., possibly more At the least, the autoguider shouldn't have to work hard. The big challenge is not to have the guiding chase the seeing.

guy

[gregbradley]

I wasn't aware of these extra menu items in The Sky so thanks for that and your reply. Very helpful.

Tell me is it normal for the mount to make reasonably quiet but odd electronic sounds a bit like a screeching electronic sound that is shifting almost like a fax machine? That is on top of the motors? I wondered if that were the PEC operating.



Thanks Guy that is very helpful as well. You guys are lifesavers.

I bought my PME 2nd hand as mentioned and the previous owner didn't have the software on discs. He got downloads for them and had one password for Tpoint which I somehow got to work on one laptop but doesn't seem to work now on another computer (I must done something different I remember it wasn't straightforward).

I have Precision PEC and Tpoint, Orchestrate, IA server and client.
Of those only Tpoint and Precision PEC are useful to me.

I refined the polar alignment last night using drift alignment and my camera and Star Targ overlay. It is quite close. Certainly if it were this close on the NJP I would get low guiding errors and round stars at 1260mm focal length.

The CDK 17 is 2939mm focal length so more than twice the focal length of the refractor.

I got elongated stars in one direction on 10 minute subs. I am using Direct Drive (a very good feature of the PME no need for an autoguiding cable the mount takes corrections along its USB cable - gee why don't all the mount manufacturers do that?).

So perhaps that is PEC not operating or polar alignment not quite good enough yet or maybe flexure as I used a 66ED refractor guidescope and ST402ME piggybacked on top. Piggybacking also can cause some odd balancing issues at different angles. I rebalanced the scope and still longish stars so balance doesn't seem to be it.

So I will check PEC is on and installed, I will try to get Tpoint operational or use my laptop to run it (the good thing about PME is no RS232 plug and socket and the electronic focuser works in USB as well).

My go-tos are also reasonably close now after about 8 synchs so polar alignment can't be too wrong.

Any other suggestions?

Greg.

[Bassnut]

Yes, thats normal, PMEs always do that, tells you its working :lol: . And the ticking sound whist guiding is handy too.



At 3m FL with an external guider, thats not suprising (flex);). You have to have the guide scope very stiff (and the cam) bolted down hard to even try to avoid that. Better to get the MOAG going, you will never get round stars with 20min subs at 3m with a guide scope no matter how hard you try.

[gregbradley]

Thanks Fred.

Yes I can see that is likely to be the case.
I just got the Lodestar working in CCDsoft yeahh! That will make it easier as it is veyr easy to slide in and out in the MMOAG so I can get focus easier (hopefully).

Also the guide scope piggybacked probably just causes balance problems at different angles.

I also just found out PEC curve is already loaded by the previous owner and I enabled it. So that may help also.

I also got Tpoint going on another computer so I can start doing a Tpoint model and tweak the polar alignment even more.

Greg.

[gregbradley]

Tried to get the MMOAG going last night but the same problem as before - nowhere near focus point for the guide cam. Even when I put a diagonal in it I couldn't achieve focus.

I think I need the negative lens accessory for the MMOAG.

I ended up activating PEC and guiding using the Lodestar and my piggybacked refractor and was getting quite round stars in 10 minute exposures.

If I tweak the polar alignment and make sure balance is perfect (it is close) I think that is a workable setup as well. I noticed the guiding would vary though depending on the area. Perhaps the angle of the scope and the balance.

.00 to .1 was the range a lot of the time but the occassional spike to .4 though.

I'm getting there. I am becoming familiar now with the PME and it is a wonderful mount. A lot of know-how has gone into it.

Is anyone using Protrack? I wonder how much more it improves things.


Greg.

[rally]

Greg,

The P-ME can be out of balance by Kgs - it just keeps working !!!

With OAGs and a rotator etc you can never perfectly balance the system anyway
This is where pier flex at the arc second level comes into play and why using Tpoint helps (but can never fix rotationally induced flexure - its not one of the terms Tpoint understands)

Protrack is just a checkbox to enable - but it only works after you have successfully created a Tpoint model - it uses the Tpoint correction model to work during tracking across the sky in real time whereas Tpoint on its own is just for pointing correction.

What is Tpoint returning as your polar alignment accuracy ?
The reason I ask - Your oval stars could be due to polar alignment or if that is near perfect then you are looking for something else.

Rally

[gregbradley]

Hi Rally,

I am not using Tpoint yet. It came 2nd hand with the mount but it is password protected and I only installed it on the Vista laptop and no record of the password. I'll email the original owner to see if he still has it.

Polar alignment so far is good but not perfect. I know, as I see image drift between exposures.

Vista is quite a barrier to all this as it fights you every of the way and installing software and hardware is a rea fight every time.

I wonder if Win 7 is better as I have a laptop that has that on it.

Greg.