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Deep Sky Scope

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#1 ClownFish

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Posted 21 September 2020 - 07:52 PM

I know this is going to cause some heated debate, but I hope I can sift through the details and make an informed  decision.  hmm.gif 
I am just about finished construction of my observatory, and have an iOptron CEM120 EC2 to handle just about any scope I can afford.

My goal is to delve into astrophotography of the smaller objects - galaxies and planetary nebula.

I have done well with wide angle work,  but now I am ready to tackle the challenge of the smaller objects.

I also want to do some planetary imaging later on.

 

So I have $4K to spend on a scope.  My observatory is a Nexdome - so about 8 feet diameter.

My seeing is pretty decent, and I have dark skies.  My observatory is in rural central New Mexico, at about 6800 ft.

 

I am currently eyeing a C11 Edge HD.  

 

Please post your thoughts as to different options, along with your reasoning.  

 

Thanks all!

 

CF

 

Observ.jpg

 


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#2 Xeroid

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Posted 21 September 2020 - 07:59 PM

C14 end of story..lol.gif


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#3 Tarzanrock

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Posted 21 September 2020 - 08:11 PM

Nice observatory.  I have an Edge 11 -- get the 14 -- that observatory deserves it and you won't regret the larger size.


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#4 ClownFish

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Posted 21 September 2020 - 08:15 PM

Nice observatory.  I have an Edge 11 -- get the 14 -- that observatory deserves it and you won't regret the larger size.

Will the 14" fit inside the Nexdome?

Does anyone have a photo of such a setup?



#5 TOMDEY

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Posted 21 September 2020 - 08:21 PM

Yeah... for "small DS targets" what you need is as much aperture as will fit in that dome. That would be a 14 or 16 inch SCT. The 14 is maybe within striking distance of your budget, and would also more comfortably fit in there.    Tom



#6 Xeroid

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Posted 21 September 2020 - 08:29 PM

One way to find out if your pier and dome will accept the C14:

 

- Get some thick card stock, approx 44 inches in length.

- Roll into a tube of 31 inches in length.

- Stick that roll onto your mount and hit the slew buttons.

- if it does not hit anything, jump for joy and have cold one...

 

Will the 14" fit inside the Nexdome?

Does anyone have a photo of such a setup?


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#7 petert913

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Posted 21 September 2020 - 08:50 PM

Great location !!



#8 ClownFish

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Posted 22 September 2020 - 08:19 AM

No one is suggesting anything other than a C14?

#9 bigjy989

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Posted 22 September 2020 - 11:33 AM

$4k is a tough limit, more options at the 15-20k range AGO, Planewave would be the usual suspects. A used 14” Edge is about ideal but you already have an 11”.

Are you looking for a different design? Any grips with your current SCT or just looking bigger? Is your seeing reliably at or under 0.5”? You might already be at the point of diminishing returns which would lead toward improving f-ratio over diameter. A10”-12” F4 imaging newt could work well in that case.

Edited by bigjy989, 22 September 2020 - 11:33 AM.

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#10 RogeZ

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Posted 22 September 2020 - 11:51 AM

If your primary goal is dso ap of small objects, I would recommend a 12” or 10” Truss RC and grow from there. I had a C14 EdgeHD and while they are great jack of all trades scopes, once you know you will be doing this type of photography the RC becomes the better choice.

Just because the mirror has no chance of lateral movement, the RC would be my choice. Much more backfocus..., perfect chromatic performance from a pure mirror system...gain the advantages are there all over the place.
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#11 ClownFish

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Posted 22 September 2020 - 12:55 PM

...but you already have an 11”.


Ah, but I don’t have the C11 yet.  I was "eyeing" it, meaning "considering it".  My only scope now is the 348mm WO Star71.  $15-20K is far out if my range.  I'm retired, and living on a very fixed income.  I could do $6K if I saved up for three additional months.



#12 ClownFish

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Posted 22 September 2020 - 12:59 PM

If your primary goal is dso ap of small objects, I would recommend a 12” or 10” Truss RC and grow from there. I had a C14 EdgeHD and while they are great jack of all trades scopes, once you know you will be doing this type of photography the RC becomes the better choice.


Great info! I was hoping to be able to run my gear remotely, and I believe the Truss RC’s require users to be there to uncap them. Maybe I’ll rethink the whole remote thing.  I see they have non-truss style RC's with covered SCT style tubes.  Those might work.   In any case, I have to make sure whatever I get will fit in this dome.  The 14" C11 with a dew shield leaves little room for error or my own movement.  



#13 rgsalinger

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Posted 22 September 2020 - 02:10 PM

So, I think that the RC scopes are a better choice than any SCT because the RC mirror never moves. The design also reduces a lot of problems associated with the big SCTs - long cool down, dewing up, thermal currents. You just need to clean the mirror every two years. (I park my PW pointing toward the ground to minimize the amount of dust and crap that falls on it.) The RC won't go out of collimation (worst RC feature) if it's just sitting in the observatory.

 

One major thing to consider as well is the REAL size of the imaging circle. While you may think that you are just going to go after small targets in the center of the field, that won't be the case for very long. Targets which just fit into the FOV are what I have found to be the most fun to image. Look on astrobin to see how good the "stars in corners" really are with either design as part of making your decision. IMHO, with a long focal length you are going to want a bigger chip than the 1600 when you have the cash. You really don't want to have to buy a new scope again when the stars look crappy in the corners!

 

I am so happy that I waited until I could afford my 12.5" Planewave for exactly those reasons. I tried a Meade 10" F8 ACF but could never get it to work properly. With the PW, I never get dew, the scope has held perfect collimation for years, the fans cool down the scope quickly each night, dew heaters are factory installed and the zero backlash focuser is a dream to operate. There's a reason the PW is getting so much bigger these days. If you think about all of the addons you will want if you were to buy a C14 - focal reducer, better focuser the cost differential might now seem so huge. I apologize to you for making a recommendation that busts your budget but I just love my PW. It's by far the best thing I've ever purchased for my AP hobby.

 

Rgrds-Ross 



#14 Lead_Weight

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Posted 22 September 2020 - 04:26 PM

I'm using an Edge 11. If you use up some of the back focus (which is pretty large) you can install a low profile crayford focuser and lock down the mirror so you don't have issues with flop. I have the ASI6200, but have also used the ASI2600 on this scope. Other than needing to work out the tilt, I think these images are pretty good.

 

Mono with the ASI 6200:

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Color with the ASI 2600:

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Pics of the setup towards the bottom of this page. You can see the Moonlite focuser installed there.

https://www.macobser...stron-edgehd-11

 

Here's some pics with the 6200 Mono installed.

https://www.macobser...00mm-pro-camera


Edited by Lead_Weight, 22 September 2020 - 04:33 PM.

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#15 ClownFish

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Posted 22 September 2020 - 05:12 PM

I'm using an Edge 11. If you use up some of the back focus (which is pretty large) you can install a low profile crayford focuser and lock down the mirror so you don't have issues with flop. I have the ASI6200, but have also used the ASI2600 on this scope. Other than needing to work out the tilt, I think these images are pretty good.

 

Mono with the ASI 6200:

get.jpg?insecureget.jpg?insecureget.jpg?insecure

 

Color with the ASI 2600:

get.jpg?insecureget.jpg?insecureget.jpg?insecure

 

Pics of the setup towards the bottom of this page. You can see the Moonlite focuser installed there.

https://www.macobser...stron-edgehd-11

 

Here's some pics with the 6200 Mono installed.

https://www.macobser...00mm-pro-camera

Thanks Andrew.  I was considering locking the C11 mirror and installing a Moonlight electronic focuser to avoid any mirror shift.  Nice shots by the way.



#16 ClownFish

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Posted 22 September 2020 - 05:15 PM

I apologize to you for making a recommendation that busts your budget but I just love my PW. It's by far the best thing I've ever purchased for my AP hobby.

 

Rgrds-Ross 

I would have to wait and save for 2 to 3 years to afford one of those.  Not happening.



#17 *skyguy*

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Posted 22 September 2020 - 05:25 PM

I've had a Meade 12" SCT in my observatory for the past 20 years. The optics are very good and they produce sharp, detailed images with tight stars. The primary mirror is spring loaded so mirror flop problems are well controlled. A new one with ACF optics is well under your budget ($600 - $1000 less).

 

A 12" f/8 Ritchey Chretien scope is also a possibility and it would be right at your budget or a little over, However, the RC OTA is about 15" longer and 11lbs. heavier than Meade 12" OTA. The length can be a factor in an 8' dome and the extra 11 lbs is never a welcomed addition.

 

Here's a 4.3 hour shot of NGC 4565 taken through my 12" SCT @f/6.3 from Bortle 4 skies:

 

NGC4565_web_160mL_30mR_30mG-50mB (2).jpg


Edited by *skyguy*, 22 September 2020 - 05:43 PM.

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#18 Lead_Weight

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Posted 22 September 2020 - 05:42 PM

Thanks Andrew.  I was considering locking the C11 mirror and installing a Moonlight electronic focuser to avoid any mirror shift.  Nice shots by the way.

One other thing to consider that you can’t do with the other scopes, is you can shoot native f10 @2800mm focal length, f7 @1960mm with the reducer or f2 with hyperstar. My shots were at f7.


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#19 ClownFish

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Posted 22 September 2020 - 05:46 PM

One other thing to consider that you can’t do with the other scopes, is you can shoot native f10 @2800mm focal length, f7 @1960mm with the reducer or f2 with hyperstar. My shots were at f7.

Yes, that's a huge selling point. 



#20 ClownFish

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Posted 22 September 2020 - 05:48 PM

I've had a Meade 12" SCT in my observatory for the past 20 years. The optics are very good and they produce sharp, detailed images with tight stars. The primary mirror is spring loaded so mirror flop problems are well controlled. A new one with ACF optics is well under your budget ($600 - $1000 less).

 

A 12" f/8 Ritchey Chretien scope is also a possibility and it would be right at your budget or a little over, However, the RC OTA is about 15" longer and 11lbs. heavier than Meade 12" OTA. The length can be a factor in an 8' dome and the extra 11 lbs is never a welcomed addition.

 

Here's a 4.3 hour shot of NGC 4565 taken through my 12" SCT @f/6.3 from Bortle 4 skies:

 

attachicon.gifNGC4565_web_160mL_30mR_30mG-50mB (2).jpg

That's a nice image!  
Your thoughts on the iOptron 12" Photron Truss Tube RC?  It's 35 inches long, easy too fit in the Nexdome, and my CEM120 can handle the weight.



#21 RogeZ

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Posted 22 September 2020 - 06:43 PM

All the GSO clones are about the same.

I would look into our sponsor, Astronomics, to see what they got.

#22 Lead_Weight

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Posted 22 September 2020 - 07:17 PM

I’ve had a few of the GSO RC’s. I would do a search on RC collimation here in the forums to see what you might come up against. One I didn’t have any trouble collimating, and the other I sold to someone more skilled than me. Haha.




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