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atlas eqg w/ 11" edge hd for ap?

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#1 cloudking

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Posted 06 April 2013 - 11:23 AM

hello CN, i have been using an atlas eqg w/ 8" cat and love it.recently purchased a 11"edge hd and thought this mount should be able to take the weight. donn't use guide scope and limmit my exposures to 1.5 to 2.0 minute subs. this mount though seems to not be up to the task. i have been very careful to ballance well and polar align but seem to have alot of tracking errors. has anyone used this combo for AP and what was your experience. always heard the atlas was underated for it's carying capacity but maybe i was wrong. any and all advise would be welcomed. :bawling: clear skies!!!!

#2 Raginar

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Posted 06 April 2013 - 12:55 PM

I'm going to say that you will not enjoy AP with that telescope and that mount. You'll end up fighting with it because it's going to be too heavy.

Suggestion for you, go to astrobin and do an equipment search. You'll find people who have done what you're trying to do and get truth data from people who have actually imaged with it.

But, I really don't think you're going to get good unguided photos anywhere near your requirement of 2 minutes. People tend to exaggerate what they're able to accomplish with the low-end mounts in my experience. Or, they are very experienced imagers who understand a particular limitation and work around it to effectively employ it when others can't.

For experience sake, I tried a 10" Meade SCT on a CGEM. It was not fun.

As you'll find most imagers say, buy the best mount you can afford.

#3 EFT

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Posted 07 April 2013 - 11:29 AM

Definitely not a recommended combination at native focal length. It's OK for visual at best. To have even a remote shot your mount would need to be tuned and working at its very best.

Now if you want to try HyperStar imaging, then you would have a much better chance at success. But it will cost you more. The Celestron focal reducer could help, but it will still be difficult and will cost you about $600.

The Atlas is not underrated at all. It's just that some people push its limits and fiddle and tweak it until it sort of works. But you would be hard pressed to find many people successfully using a C11 at native focal length for AP on the Atlas. Not impossible, just highly difficult.

Also, if you are not guiding, then you are wasting your time on this mount (on just about any mount with an SCT for that matter).

#4 JMW

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Posted 07 April 2013 - 11:48 AM

I use the C11 EdgeHD on an AP900GTO. With off axis guiding I can go 20-30 minutes when doing narrowband Ha exposures. When guiding with a piggy backed scope the stars are not acceptable after a few minutes due to mirror shift. My previous mount was an Atlas and I enjoyed imaging with my refractors but my C9.25 scope was difficult due to not using an off axis guider.

I am actually amazed that you had success with you 8 inch SCT without guiding. Off axis guiding or Hyperstar is the best way to have consistent results with an SCT.

#5 CounterWeight

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Posted 07 April 2013 - 12:04 PM

In agreement with all the above "+1". Wow a Edge 11" nice! but then reality too...

There are big defferences in getting something to work once, work all night(or part of it), work all night every night. (It seems you're already experiencing this) Imaging is about 'the whole kit' working reliably and repeatably. Large apeture and long focal length imaging imaging require a significant imaging mount. You can dial down apeture and focal length and the requirements loosen up 'a little'. So I'd recommend for imaging sticking with the 8" cat and reducing it with the f/6.3, and then getting something to autoguide with like the Orion Miniguider. So I also recommend to start out with using a setup that uses guiding, and autoguide. It can only help, even with shorter exposures.

#6 cloudking

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Posted 10 April 2013 - 04:06 PM

thaks for your comments. i do all my ap with focal reducers ( 8" and 11" ). i'v done subs of up to 3 minutes with the 8" @ f6.3 with very good results after trial and error. i quess i knew this was a bad combo but got a good deal on the 11". i was considering the losmandy g11 w/ 60 lb. payload ( the 11" with acessories is about 35lbs). i'v heard there very good mounts and few people if any seem to have any real problems with them. i think that is bout the most mount i can afford right now but was hoping i wouldn't have to make that decision. will try to figure out deap sky staker and start taking shorter subs , haven't had any luck staking so far, guess i am just not that computor literate. thanks again. clear skies. :cool:

#7 Raginar

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Posted 10 April 2013 - 07:23 PM

A G11 would work fine with a C11 (probably maxxed out actually, but it handles that much better than the cheaper mounts).
If you're getting into AP and think it'll be a long term thing, get a good mount. It's the best investment in the hobby you can make.

Good luck with the C11!

#8 cloudking

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Posted 11 April 2013 - 09:13 AM

If i were to use an off axis guider would i expect much better results. weight is an issue already so i don't want to add guide scope but since i have not used guiding before i have read that off axis guiding is somewhat hard to do (i.e. star aquisition ) but prefered for sct scopes. also would a stand alone such as nexguide work well? or am i dodging the main issue of " it's all about the mount". don,t use a lap top and trying to avoidall he hardware. most of my imaging is doneat remote site so portable is an issue.

#9 orion69

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Posted 11 April 2013 - 09:23 AM

@cloudking

I'll make one suggestion, hope you don't mind...
Keep your 11" edge for visual and buy yourself 80mm f/6 APO for AP. You'll be amazed...

And please do guide, why would anyone want to do unguided imaging? Unless you have high end mount, of course...

#10 cloudking

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Posted 11 April 2013 - 09:45 AM

with a bit of trial and error i was able to take some decent images with the 8" @f6.3 using a cannon t2i unmodded ( images attached ) but wondering if off axis guiding might help. what setup do you use for guiding? I have only been at this for about a year and a half

note: images are single exposures of about 2 minutes each and prossesed and cropped in digital photo profesional.

#11 Raginar

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Posted 11 April 2013 - 03:48 PM

OAG will help. Make sure you get a good camera; something like an STi or a Lodestar since it has a very narrow FOV. The biggest problem with OAGs is they cost about as much as the guide rig. It will save you weight. If you're willing to spend 1200 bucks, an ONG would be pretty neat.

#12 olivdeso

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Posted 12 April 2013 - 05:30 PM

Off axis guiding or Hyperstar is the best way to have consistent results with an SCT.

+1

I would add OAG + reducer.

ONAG is also possible on classical SCT. ONAG = On Axis guider. There is a semi-reflextive diagonnal which reflect the visible spectrum at 90°, to the main sensor, while the Ir emission passes through the glass, going to the guiding sensor. This require a lot of backfocus, so almost compatible with SCT.

On edge SCT, le backfocus is 146mm (same with or without reducter). The ONAG might be too long, depending on your camera.

If you really want to do some imaging with the C11 on the Atlas, at least an OAG + a reducer is needed.

Also big pixels are required: about 15µ pixels without reducer (or 7.5µ in bin 2 mode)and 9µ pixels with the x0.7 reducer which already gives about 1" per pixel.

If still not good enough, then you may either try the Active Optics (SXV AO, Sbig AO, Orion AO...) or upgrade the mount.

#13 cloudking

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Posted 14 April 2013 - 07:50 AM

OAG seems like a good way to go for now. checked out the loadstar and that looks like a good guiding camera. looking at oag's and just want to find something that will perform well. I know the mount is still an issue but since my ota's are all cats , off axis guiding is still necessary. I really enjoy imaging and will be for some time to come. growing my rig as I go. as always thanks for your input, it has opened my eyes. the people on CN rock!! clear skies :grin:

#14 Raginar

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Posted 14 April 2013 - 09:19 AM

Get a finder guider if you have 80 bucks free. You will find an OAG to be a challenge, and you might find the finder guider works just fine.

#15 cloudking

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Posted 14 April 2013 - 09:56 AM

a finder guider sounds like an inexpensive way to go but i have heard that with a sct ( long focal length ota's ) that the focal length of the guider shold be at least half the ota's fl. not to mention that oag guiding is prefered for sct's due to mirror flop. the money doesn't bother me so much as the end result. i have heard finding guide star with oag can be dificult but if a good oag is used is it realy that dificult. i am concerned about being able to focus giude camera and imaging camera ( i'm using t2i dslr ). also i probably will be upgrading my mount when funds are available but for now as far as bang for the buck is concerned oag seemed like good fit for my scopes regardles of the mount. i just want to make equipment choices based on future growth as well as economics.

#16 Raginar

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Posted 14 April 2013 - 01:25 PM

Can't wait to see your pictures! Good luck! :)






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