Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Mounts

Pages: 1 | 2 | (show all)
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
About to trash my whole setup.
      #5427176 - 09/18/12 11:31 AM

Im so frustrated, i just dont know what to do.
Im getting oblong stars. They all are oblong in the RA direction.
Im using a Losmandy G11, with an 10"lx200. Permanently mounted in my obs.. Even with autoguiding i can not get round stars.
Ive polar aligned and realigned. Ive collimated over and over again. Ive checked that the gears are meshed correctly. I even have the ovision worm. I have cleaned the main gear and worm and relubed.. And my pe is somewhere in the 7 range consistantly.
Ive used mirror lockup in the dslr. Ive reset the mount. Ive done everything i can think of and im sure im missing some things that i havent listed here.

This is soo frustrating because just 1year ago i could get round stars in a 10minute unguided exposure.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Peter in Reno
Postmaster
*****

Reged: 07/15/08

Loc: Reno, NV
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427187 - 09/18/12 11:37 AM

If you are using guide scope, have you considered OAG? You'll be surprised of the results. I was getting exactly the same thing with a guide scope guiding an SCT until I threw away the guide scope and replaced it with OAG and Lodestar.

Peter


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: Peter in Reno]
      #5427189 - 09/18/12 11:39 AM

No, not really. Ill have to do some reading.

Post Extras: Print Post   Remind Me!   Notify Moderator  
EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427190 - 09/18/12 11:39 AM

What have you done to start eliminating the possible sources of the problem?

Do you have a smaller scope that you could try out, like maybe a refractor, so see if the problem is in the scope, dovetail, etc.?

Narrowing things down to the mount or the scope/imaging train will probably help.


Post Extras: Print Post   Remind Me!   Notify Moderator  
D_talley
Carpal Tunnel
*****

Reged: 07/07/05

Loc: Richmond VA
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427191 - 09/18/12 11:39 AM

Have you locked the mirror on the scope, if that is possible?

Also, what happened in the past year that could affect the mount's performance. When did the O-worm get installed?

The fact that images are showing oblong stars even when guiding points me to the main scope mirror shifting or the guider mount shifting.


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: EFT]
      #5427214 - 09/18/12 11:50 AM

Quote:

What have you done to start eliminating the possible sources of the problem?

Do you have a smaller scope that you could try out, like maybe a refractor, so see if the problem is in the scope, dovetail, etc.?

Narrowing things down to the mount or the scope/imaging train will probably help.



I dont have any other scopes to try. How else can i narrow it down?


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: D_talley]
      #5427223 - 09/18/12 11:55 AM

Quote:

Have you locked the mirror on the scope, if that is possible?

Also, what happened in the past year that could affect the mount's performance. When did the O-worm get installed?

The fact that images are showing oblong stars even when guiding points me to the main scope mirror shifting or the guider mount shifting.



I have not tried locking the mirror. Not sure its possible now that i think about it though.

The o-worm has been on the mount since i bought it.

I wonder if youre right about the mirror shifting. But the stars are oblong even in short exposures. Say of about a minute or so. And whats strange is that they dont seem to really get worse in longer exposures.. Maybe something in the camera????


Post Extras: Print Post   Remind Me!   Notify Moderator  
Stew57
Carpal Tunnel
*****

Reged: 05/03/09

Loc: Silsbee Texas
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427235 - 09/18/12 12:00 PM

Try rotating the camera 90 degrees. See if the direction of star elongation moves with the camera or is in the same orientation you have now.

Post Extras: Print Post   Remind Me!   Notify Moderator  
EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427239 - 09/18/12 12:03 PM

Quote:

Quote:

What have you done to start eliminating the possible sources of the problem?

Do you have a smaller scope that you could try out, like maybe a refractor, so see if the problem is in the scope, dovetail, etc.?

Narrowing things down to the mount or the scope/imaging train will probably help.



I dont have any other scopes to try. How else can i narrow it down?




That is going to make things tough. I suspect the problem is in the scope/imaging train and is most likely due to flexture. However, the new worm could be the issue as well.

If you upgraded to the new worm yourself, then you could put the old one back in and see what that does so that you can eliminate or verify that the new worm is the problem.


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: Stew57]
      #5427240 - 09/18/12 12:03 PM

Why didnt i think of that. haha I must try that tonight.

Thanks!


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: EFT]
      #5427250 - 09/18/12 12:08 PM

Quote:

Quote:

Quote:

What have you done to start eliminating the possible sources of the problem?

Do you have a smaller scope that you could try out, like maybe a refractor, so see if the problem is in the scope, dovetail, etc.?

Narrowing things down to the mount or the scope/imaging train will probably help.



I dont have any other scopes to try. How else can i narrow it down?




That is going to make things tough. I suspect the problem is in the scope/imaging train and is most likely due to flexture. However, the new worm could be the issue as well.

If you upgraded to the new worm yourself, then you could put the old one back in and see what that does so that you can eliminate or verify that the new worm is the problem.


I doubt the worm is the issue. Ive had very good success with it in the past. So had the previous owner.. So i could try the old worm...

Should i take the scope and everything off the mount, reasemble everything so make sure everything is tight?
I just dont get how i used to get good images and now i get movement...


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427255 - 09/18/12 12:10 PM

Actually i think you guys are right about flexure. Due to the fact i have a hard time getting good GOTO's..

Post Extras: Print Post   Remind Me!   Notify Moderator  
tjugo
scholastic sledgehammer


Reged: 11/06/07

Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427285 - 09/18/12 12:25 PM

Hi,

I was debugging a similar issue with my setup, Atlas + Epsilon 160 + short guidescope. The guide graph looked very flat but I was getting elongated stars mostly in the RA axis.

I tried everything, change guiding params, switch back and forth from maxim to PHD, change guide scope, drift alignment, PEC etc etc....

Long story short, the problem was some small amount mirror shift, usually mirror shift produces double stars but in my case it was producing elongated stars. I put together my old OAG and the stars are round and small again.

Some people suggested that the issue was focuser flex , probably, but the OAG took care of the problem.

Cheers,

Jose

Edited by tjugo (09/18/12 12:28 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
freestar8n
Post Laureate
*****

Reged: 10/12/07

Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427456 - 09/18/12 01:43 PM

Quote:

Im so frustrated, i just dont know what to do.




OAG

Frank


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jared
Post Laureate
*****

Reged: 10/11/05

Loc: Piedmont, California, U.S.
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427642 - 09/18/12 03:31 PM

If you look at your guide results are they good? Based on the log, what is the RMS guide error? Do the RA and DEC numbers look similar?

If the guider is reporting good results, but you still have elongation in your stars you are likely looking at differential flexure and/or mirror flop. Frankly, that's to be expected using a guide scope with an SCT--especially one with no mirror locks. The only thing that makes me at all suspicious is the fact that your error was in RA. With differential flexure, the direction of the elongation will vary with the object.

Basically, with a 10" SCT used at Cassegrain focus (even with a reducer) you are likely to get better results with an OAG. The only downside is that it can be hard finding a guide star. That and the fact that you'd have to buy a guider.


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: Jared]
      #5427661 - 09/18/12 03:39 PM

Thanks all! Im going to try a few new things tonight. Also ordered an OAG.. We will see how it works tomorow night.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Peter in Reno
Postmaster
*****

Reged: 07/15/08

Loc: Reno, NV
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427683 - 09/18/12 03:52 PM

Which brand OAG did you get? What brand autoguider are you using?

Peter


Post Extras: Print Post   Remind Me!   Notify Moderator  
brokenwave
sage


Reged: 05/10/11

Loc: Scottsdale, AZ
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5427694 - 09/18/12 03:57 PM

Are you using a remote cable or program to trip shutter? and if you don't have a 5-10 delay after mirror flips up you are probably getting bounce somewhere. Try this:
If your exposures are short say 10 sec. or less. You might be getting bounce from the camera shutter. Try increasing your exposures by 5 seconds or so and use a dark piece of cardboard to block the front of the tube for that 5 seconds,
without touching the tube with it.
That will let what ever is bouncing settle down without the camera being exposed to what you are photographing. It will take that out of the problem solving if it isn't tracking error. Since you longer exposures are the same as short ones it sounds like something isn't totally locked.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Alterf
professor emeritus
*****

Reged: 04/07/06

Re: About to trash my whole setup. new [Re: brokenwave]
      #5428024 - 09/18/12 06:36 PM

A friend had a similar problem and found that there was play in the RA. Adjusting the RA backlash and tightening things down cured it. I hope you can find the source of the problem. Nothing is more frustrating.

Val


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: Alterf]
      #5428518 - 09/19/12 12:27 AM

Im bummed. Im out in the obs right now and im seeing huge jumps in the RA...
Its def in the mount and not the camera.
Today i took everything off the pier and started over.
I even left off the spotting scope and the guide setup to save a bit of weight.


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5428520 - 09/19/12 12:29 AM

AHHHHH!!!!!! What the #(*(*&@$ changed in the last year?????

Post Extras: Print Post   Remind Me!   Notify Moderator  
EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5428531 - 09/19/12 12:38 AM

Have you ever completely stripped the mount down and cleaned everything out? It's hard to think of what might be wrong with the mount if your PE is down at 7 (is that +/-7 or +/-3.5?). How is the total error, random and periodic? It is possible that you have a bad bearing in either the worm or, less likely, the axis that is causing the problem. There might also be debris of some king in the axis roller bearings.

Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: EFT]
      #5428555 - 09/19/12 12:55 AM

Its +-7.. pempro didn't do a good job correcting it. There is some periodic error that I can see but also alot of random error. Error that pec won't correct out.
I know that 7 doesn't seem too bad but keep in mind that I have the ovision worm. And I used to get round stars at 10mins at 1600mm focal length. Seems impossible now.
Whatever I do its the same result.
Should I tear the mount down? Thats really uncharted waters for me. But it seems like that's where all this is heading.


Post Extras: Print Post   Remind Me!   Notify Moderator  
EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5428610 - 09/19/12 01:27 AM

Actually, +/-7 isn't all that great for that mount. However, it is the random error that may be the greater problem depending on how steep the PE error is. If you can really eliminate the OTA/image train as the source of the problem, then the mount's change over time is probably a good indication of the need for a strip down and tuneup. When you are out in an observatory, it is easy to get everything from dirt to bugs inside a mount that will cause problems that will degrade the mount's performance over time. The G-11 is pretty tough and I've seen some that were really abused but cleaned up just fine, but and occasional tuneup can do them good. It's not the most difficult mount in the world to work on except for the axis roller bearings which are a real pain to remove.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Tori
sage


Reged: 01/10/12

Loc: Somerville, MA/Warren, NH
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5428773 - 09/19/12 06:26 AM

How permanent is your pier? Is it isolated from your footsteps? Any chance that YOUR movement is causing the problem?

Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: Tori]
      #5428897 - 09/19/12 09:25 AM

Quote:

How permanent is your pier? Is it isolated from your footsteps? Any chance that YOUR movement is causing the problem?



Its pretty well isolated. 4ft x 4ft x 2ft concrete base with a 12" sonotube as the pier. The obs was then built around that. Being careful not to touch the pier with the building.


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5428949 - 09/19/12 10:14 AM

OK. So I guess I'm going to tackle disassembling and cleaning the mount today. I'm dreading doing it but I've found some good writeups. My father is going to help me so ill have an extra set of eyes there. Hopefully ill get this sorted out. I've just been so frustrated for the last 6mo.

Post Extras: Print Post   Remind Me!   Notify Moderator  
D_talley
Carpal Tunnel
*****

Reged: 07/07/05

Loc: Richmond VA
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5429122 - 09/19/12 12:10 PM

Remember to photograph the tear down so you can remember where part go. Good luck

Post Extras: Print Post   Remind Me!   Notify Moderator  
Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5429322 - 09/19/12 02:16 PM

Quote:

Im so frustrated, i just dont know what to do.
Im getting oblong stars. They all are oblong in the RA direction.
Im using a Losmandy G11, with an 10"lx200. Permanently mounted in my obs.. Even with autoguiding i can not get round stars.
Ive polar aligned and realigned. Ive collimated over and over again. Ive checked that the gears are meshed correctly. I even have the ovision worm. I have cleaned the main gear and worm and relubed.. And my pe is somewhere in the 7 range consistantly.
Ive used mirror lockup in the dslr. Ive reset the mount. Ive done everything i can think of and im sure im missing some things that i havent listed here.

This is soo frustrating because just 1year ago i could get round stars in a 10minute unguided exposure.



It's not what you want to hear, but it was at exactly this point, with a new Ovision worm, that I gave up on the G11 for astroimaging and put my name on the list for a Mach1GTO. Eight months later I had my Mach1, and I've never been sorry. In the meantime, I suggest that you check, for example, the aggressiveness in your guiding software. You can get into a situation where the guiding oscillates between equally unacceptable errors, and adjusting the aggressiveness or simply cancelling everything and restarting without changes may cure the problem.


Post Extras: Print Post   Remind Me!   Notify Moderator  
powerstroke01
sage


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: About to trash my whole setup. new [Re: Calypte]
      #5429432 - 09/19/12 03:33 PM

Yeah theres no way i could afford a new mount right now.

Post Extras: Print Post   Remind Me!   Notify Moderator  
evilmedic13
member


Reged: 06/23/12

Loc: Chicago,Il
Re: About to trash my whole setup. new [Re: D_talley]
      #5429555 - 09/19/12 04:54 PM

Quote:

Remember to photograph the tear down so you can remember where part go. Good luck




Definitely! Someone told me to do this a long time ago, for working on my motorcycles. I thought it was a waste of time, but still did it. Then, one day, I ended up with an "extra" part. It belonged to my rear brakes, somehow I missed putting a bolt on. If it wasn't for the pics, I never would've known where it went, and chalked it up to one of my many spares I have(I always order extra parts). Until it would have been too late.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: About to trash my whole setup. new [Re: powerstroke01]
      #5430106 - 09/19/12 11:30 PM

Hummm -- I assume you are carefully balanced. When I get huge jumps in RA it is usually a balance issue. And, occasionally it is due to training my little Meade Pro in the E and then trying to image in the W without retraining. I use PhD.

Ed


Post Extras: Print Post   Remind Me!   Notify Moderator  
CounterWeight
Postmaster
*****

Reged: 10/05/08

Loc: Palo alto, CA.
Re: About to trash my whole setup. new [Re: Ed Wiley]
      #5430274 - 09/20/12 02:25 AM

I just went through something like this with my Mach1 ! yes! 'believe it or not! went from great 20 minute subs to not being able to get a good 5 minute sub. Incredibly frustrating as it all a sudden happened. And I'm also perm mounted and have a 'ROR' so nothing changed, just could not for the life of me get get a round star. Couldn't buy a mach-1 as I already own one, and it was the problem!

The fix was too complicatd and still not complete! The worst thing is the little safety feature in the AT/FF i use... the dreaded 'cutout' or whatever it is called - just will not line up with the focuser collet on the ED80T and so my imager not perfectly 'ortho'... that took forever to isolate. Next was meshing... yes I finally re-meshed after however long it was... but it took several tries. Went exactly by the manual and phoned A-P excellent customer support several times. Polar aligned, even finally drifted... still eggs everywhere. At this point I'd tried both PHD and MaximDL so many times with so many setting I'd developed a large matrix!

But still no real change - and it's so much like what you say - seemed to be somewhat same no matter the exposure time. Having 10 nights in a row to try and fix /test in Portand OR is unheard of in the the last 3 years but this year, every night clear! Pure imaging gold here! Every night 'wasted'... maddening. Swapping scopes, swapping SSAGs ! swapping cables... polar aligning and re-polar aligning. Checking computer and USB and ASCOM and 'you name it' - almost seemed like there was a 'latency' issue in the USB bus timing /management... oh the thoughts that went through my half functional head...

It was changing scopes and imaging trane that FINALLY isolated the blasted demon cutout on the AT/FF and as I say - I still don't have a perm fix for it though I'm thinking meatal foil duct tape may provide a path to fill the blasted thing in.


No real moral here I can think of except don't rule out that it may be more than one cause. The fact that it became apparent at one point in time could be arbitrary.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: About to trash my whole setup. new [Re: CounterWeight]
      #5431034 - 09/20/12 02:08 PM

Quote:

The worst thing is the little safety feature in the AT/FF i use



Well, Why didn't you get RF/SS?


Post Extras: Print Post   Remind Me!   Notify Moderator  
JoseBorrero
Post Laureate
*****

Reged: 09/04/09

Loc: Puerto Rico Island
Re: About to trash my whole setup. new [Re: Alph]
      #5431458 - 09/20/12 06:44 PM

If using the ascom gemini make sure to reset the mount modeling. They're several version on gemini yahoo group. I have my mount set up in my backyard for almost a month now "first time" just covering between shower and rain, so far I like it. I do polar aligning anyway everytime and reset my modeling settings. It happen like two months ago I downloaded a old version of Ascom gemini and it results the modeling was still adding this data even changing optics it need to be reset. Well, symptoms include bad goto and the RA running like hell. Also I for got that I was playing with guide rate at is has several speeds. That experience was really messy and at least I learn another problem.

Also OAG solve this problems for sure!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | (show all)


Extra information
21 registered and 33 anonymous users are browsing this forum.

Moderator:  Dave M, richard7, bilgebay, iceblaze 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1936

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics