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Imaging with 9.25 Edge on Atlas EQ-G?

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#1 exmedia

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Posted 28 July 2014 - 04:31 PM

Any thoughts on imaging with a Celestron 9.25" Edge on an Atlas EQ-G Mount? Primarily I'm wondering if it would be too much weight for accurate guiding. 21 lbs OTA + 6-7 lbs guide scope & DSLR = ~28 lbs on a mount rated for 40. I've read that the Atlas is more capable than the rating would indicate.

Thanks,

Richard

#2 BKBrown

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Posted 28 July 2014 - 05:33 PM

Richard,
The Atlas and C925 are a great combination for imaging. If the additional weight of a guide scope worries you, pick up an OAG and use it with your guider instead...

Clear Skies,
Brian

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#3 orlyandico

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Posted 28 July 2014 - 06:56 PM

Weight wise it "seems" doable.

But focal length wise.. it is going to be a challenge. The C9.25 is very, very long (2350mm focal length). With a typical DSLR you're looking at a pixel scale of 0.4"/pixel which is a very tough nut to crack.

I never tried using my old C9.25 on my CGEM (which is similar to the Atlas, although arguably performs less well) because simple math didn't work out.

The CGEM could not guide to lower than ~ 1.5" RMS due to its gritty gears. My seeing also isn't so good. I assume an Atlas could guide better than the CGEM since the Atlas has a simpler gearbox and doesn't have the 8/3 error, but I still think 0.4" pixel scale is still asking too much of this mount.

Suggestions would be

1) get a better mount, like an AP

2) if the above isn't possible, use the reducer to bring things down to f/7 which is about 0.6" per pixel.. still pretty tough

3) use a Hyperstar, at which point all your mount troubles should disappear

4) I would argue that the non-EDGE C9.25 might be a better choice as you can use the (much cheaper than the EDGE reducer) Optec 0.5X reducer which also has a much greater reduction ratio, which makes things a lot faster and makes the task for your mount a lot easier

You will certainly need an OAG.

Bottom line, DSO imaging with an SCT is always going to be challenging, and I frankly don't find the Atlas/CGEM type mounts to be ideal for it.

If your goal is planetary however, all of my caveats above are irrelevant.

As to BKBrown's reply above, his picture shows a planetary camera (it seems) attached to his scope. I am not sure if he did any DSO imaging with the C9.25 + Atlas.

#4 Foehammer

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Posted 30 July 2014 - 02:14 PM

I have a similar setup, a non-edge 9,25 with an ST80 piggybacked riding on the NEQ6 (Skywatcher's version of the Atlas). I won't lie to you, it is tricky but with a reducer (I'm using the Celestron 6.3) it certainly is doable and the results will please you. Balance is critical as you would guess. I am quite the beginner in DSO imaging (I'm mainly a planetary guy) but I have managed half-decent results with my DSLR. The 9,25 is a remarkable scope. Here's my latest: M27 with the 9,25 at f/6.3 guided with the ST80 and ASI120mono, 25x 300sec shots. Not the best out there but you get my point!

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#5 BKBrown

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Posted 30 July 2014 - 04:47 PM

As to BKBrown's reply above, his picture shows a planetary camera (it seems) attached to his scope. I am not sure if he did any DSO imaging with the C9.25 + Atlas.



I must confess that I never did DSO imaging with the C925...but I did with my C11 Edge at native focal length on that same Atlas :grin: Since M27 is already up in this thread, I will add my contribution. Here it is, my very first DSO image ever acquired with my C11 Edge HD, it was shot at f/10 on a very well balanced Atlas through a Hutech modded T1I (500DH) w/ a light pollution filter. This image is a stack of 30 x 90sec subs w/ dark frames and flats, stacked in DSS and finished in PS CS4. Now that Atlas was mounted on a 12" concrete and rebar pier in my observatory, but it was also pretty much rock steady on the Losmandy HD tripod you see in my first image. The biggest problem with the Atlas is the lame factory tripod. Add a stabilizing tray to the Atlas, or a beefier tripod, and you can do solid work. Of course if you can swing an AP...
Give the C925 a go, especially with a focal reducer. It should be manageable on an Atlas if everything is tight and properly balanced. As for guiding, the OAG is a good suggestion. But for that M27 I used a leftover Celestron 9x50 finder scope, so-so adapter with its edges ground down and worked into the finder, and an Orion SSAG. Some folks say that just can't work, I'm not convinced :grin:

Clear Skies,
Brian

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#6 Benson

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Posted 06 August 2014 - 02:14 AM

I feel the EQ-G is suspect for AP. Some people achieve good results with this combo, but, it probably won't be satisfactory for less than an expert. A Losmandy G8 would be a better choice, IMO.



#7 rmollise

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Posted 06 August 2014 - 12:40 PM

Weight wise it "seems" doable.

But focal length wise.. it is going to be a challenge. The C9.25 is very, very long (2350mm focal length). With a typical DSLR you're looking at a pixel scale of 0.4"/pixel which is a very tough nut to crack.

 

 

 

Few people want to image at f/10. At f/6 - f/7 imaging/guiding is easy with this combo. ;)



#8 wargrafix

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Posted 06 August 2014 - 01:56 PM

I have imaged at f/10, unless you have everything ticking right, it can be a virtual nightmare. Imaging will go fine...its stacking where you will see true issues.



#9 Ron359

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Posted 06 August 2014 - 11:53 PM

I've mostly done observing and planet imaging w my standard 9.25. But this year I started DSLR imaging on an  EQ-G (original non-goto model).  This past winter I started auto guiding using the little Orion 50mm guidescope and PHD. It worked fine at full focal length and recently did some with a .63 reducer.   Using the 50mm saves a chunk a weight from a traditional longer guide scope or hassles of an OAG.   I'd say go for it.    Ron



#10 bluedandelion

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Posted 07 August 2014 - 11:52 AM

I was crazy enough to start with the Atlas, C9.25 classic and a 350D DSLR and imaged at f/10. If you want to jump in the deep end and learn to swim to save your life, this is the way to go :lol:

 

Notice the amount of counterweight (35lbs) in the picture below with a later set up:

CatAtSunset 3
 

I did get a few good images, but most were subpar.

8152988240_40893ff404_m.jpg

 

Be ready to do battle and use an OAG if you want good results. Go f/6.3 if you value your sanity.

Ajay


Edited by bluedandelion, 07 August 2014 - 12:13 PM.


#11 Ron359

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Posted 07 August 2014 - 05:12 PM

I was crazy enough to start with the Atlas, C9.25 classic and a 350D DSLR and imaged at f/10. If you want to jump in the deep end and learn to swim to save your life, this is the way to go :lol:

 

Notice the amount of counterweight (35lbs) in the picture below with a later set up:

 
 

I did get a few good images, but most were subpar.

 

 

Be ready to do battle and use an OAG if you want good results. Go f/6.3 if you value your sanity.

Ajay

 

I suggest you get a side-by-side saddle mount for that piggyback refractor and it will eliminate a counterweight or two and return your sanity.    :)    Ron



#12 bluedandelion

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Posted 07 August 2014 - 05:49 PM

I suggest you get a side-by-side saddle mount for that piggyback refractor and it will eliminate a counterweight or two and return your sanity.    :)    Ron

 

 

Not to worry, I don't image with the C9.25 any more. Imaging nights and processing days are now so much more tranquil. :meditate:

 

Ajay


Edited by bluedandelion, 07 August 2014 - 05:50 PM.


#13 rigel123

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Posted 08 August 2014 - 02:37 PM

Any thoughts on imaging with a Celestron 9.25" Edge on an Atlas EQ-G Mount? Primarily I'm wondering if it would be too much weight for accurate guiding. 21 lbs OTA + 6-7 lbs guide scope & DSLR = ~28 lbs on a mount rated for 40. I've read that the Atlas is more capable than the rating would indicate.

Thanks,

Richard

I use mine for Planetary Nebula at native f10 since many are bright and you can use shorter exposures making guiding a bit less demanding.  I guide with a 50mm Orion Mini Guide set up.

 

get.jpg

 

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get.jpg



#14 Adeema

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Posted 11 August 2014 - 10:37 AM

I was contemplating a C9.25 as well to go with my Atlas. I'm mainly visual but AP is on my list of things to attempt later in life.

 

Would a C8 or EdgeHD 8 be easier, or the fact that they're both f/10 mean it's just as difficult?



#15 bluedandelion

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Posted 12 August 2014 - 12:23 AM

I think the C8 is more manageable from the point of view of weight and size.

 

I have not imaged with a C-8 and definitely not an Edge variety of any SCT. For me the problem with SCTs was the quality of stars I got. As you advance in this hobby, you start paying attention to such things. With the type of seeing my location is blessed with at Hazy Hollow observatory ( :( ) in Western Washington, the dew, falling temps most of the night etc., a refractor was the best solution. Then there's mirror shift, mirror flop, focusing - a whole host of problems to contend with. I overcame them one by one, but the trouble was too much and some of them never really go away. An OAG is almost a must if you want to do serious imaging with an SCT and get small round stars, but I know a lot of people who swear at OAGs instead of by them - although I managed to get one working.

 

A lot depends on what type of images will make you happy. If you are going to do casual AP the C-8 would probaly be jsut fine. The edge might be better, I don't know, but if you are going to get into serious AP a corrected reflector, or an RC is probably better for long focal length. A medium focal length refractor would be a lot more forgiving, but price can be a factor.

 

Ajay


Edited by bluedandelion, 12 August 2014 - 12:26 AM.


#16 Adeema

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Posted 12 August 2014 - 10:14 AM

I was planning on starting with my ED80, which will hopefully ease me into the hobby. I was just wondering if I were to get an 8 or 9.25 SCT for visual that I would eventually be able to use it for AP as well. Sounds like I have a long way to go before I'm at that point, plenty of practice to be done with the ED80 first!








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