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What's the best bang-for-your-buck 8" telescope that is good for deep space astrophotography?

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#1 Branithar

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Posted 24 October 2021 - 12:26 PM

I've seen 8" reflectors that range from $1,500 to $4,000, and range from f/15 to f/2. I have a color planetary camera and DSLR, and eventually I'll want to get a cooled deep space camera. What telescopes provide a lot of bang-for-your-buck, and do well with deep space astrophotography?


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#2 petert913

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Posted 24 October 2021 - 12:45 PM

Many say it is not optimum, but I find an 8" SCT with focal reducer is the most convenient way to get good deep sky photos.


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#3 bobzeq25

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Posted 24 October 2021 - 12:47 PM

You _need_ to distinguish between two things, often confused here.  _Learning_ DSO AP, and _doing_ DSO AP.  Or you'll be in a world of hurt, and misunderstand the responses here.

 

So, what 8 inch scope is good for learning DSO AP?  None.  8 inches is way too big.  The ideal starter scope is a 51-80mm refractor.  And bigger is not better.  This ain't visual.  Understatement.  A big scope makes a difficult task much harder.  You don't want to go there.  <smile>

 

Bang for the buck 8 inch scope for doing DSO AP?  A Newtonian.  Speed is helpful.  F5 is good, F4 gets tricky.

 

Just don't start out with one.

 

And, that was the classic wrong question.  The mount is the most important part of a DSO AP setup, not the scope (or the camera). 

 

The two top beginner mistakes.  Skimping on the all important mount.  Trying to start with too big a scope.  Avoid those, and you'll be starting out optimally.

 

Good mount.  Small refractor.  Breakfast of Champions.  <smile>


Edited by bobzeq25, 24 October 2021 - 12:51 PM.

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#4 zakry3323

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Posted 24 October 2021 - 01:10 PM

What Bob said. Nice inexpensive 8" newt f/5 or f/6 on a dobsonian base is great for visual and can provide a lifetime of interesting targets. It's not impossible, but would certainly be a pain to try to learn traditional astrophotography on a big manually driven OTA. 



#5 Mitrovarr

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Posted 24 October 2021 - 01:26 PM

They sell newtonians specifically made for astrophotography now. They're really fast and the focuser, etc. are designed to for that purpose. They're also cheap.

Keep in mind you will need a huge and expensive mount to do AP with an 8" scope.


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#6 Branithar

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Posted 24 October 2021 - 01:30 PM

Well, I mostly want the equatorial mount, and 8" seems good for getting some nice details in planets. And visual astronomy and manual tracking seems more fun with with an eq mount than my twitchy motorized alt az mount.

#7 ewave

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Posted 24 October 2021 - 01:43 PM

Nothing wrong with wanting 8" of aperture, but keep in mind this:

Visual is most affordable and an 8" is usually the best bang for the buck.

OTOH, astrophotography (DSOs) is usually very expensive, and is the gift that keeps on giving.


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#8 ICit2

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Posted 24 October 2021 - 01:44 PM

You _need_ to distinguish between two things, often confused here.  _Learning_ DSO AP, and _doing_ DSO AP.  Or you'll be in a world of hurt, and misunderstand the responses here.

 

So, what 8 inch scope is good for learning DSO AP?  None.  8 inches is way too big.  The ideal starter scope is a 51-80mm refractor.  And bigger is not better.  This ain't visual.  Understatement.  A big scope makes a difficult task much harder.  You don't want to go there.  <smile>

 

Bang for the buck 8 inch scope for doing DSO AP?  A Newtonian.  Speed is helpful.  F5 is good, F4 gets tricky.

 

Just don't start out with one.

 

And, that was the classic wrong question.  The mount is the most important part of a DSO AP setup, not the scope (or the camera). 

 

The two top beginner mistakes.  Skimping on the all important mount.  Trying to start with too big a scope.  Avoid those, and you'll be starting out optimally.

 

Good mount.  Small refractor.  Breakfast of Champions.  <smile>

bobzeq25 is spot on.  But if you're really bent on larger aperture and going deep, then a 6" RC (Ritchey-Chrétien Telescope) would do the trick.  At 1370fl and weighting in at 12lb it's much more manageable then a SCT with no coma up to a APS-C sensor.   The focuser on them is just ok for a DSLR.  But if you're thinking of adding on a filter-wheel ect then it will require an upgrade.  It's also difficult to attach a EAF (Electronic Auto Focuser) with the standard focuser.

Cheers!  
 



#9 Mitrovarr

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Posted 24 October 2021 - 02:06 PM

Well, I mostly want the equatorial mount, and 8" seems good for getting some nice details in planets.

Planetary AP is a completely different process than Deep Sky AP and requires totally different equipment. Is planetary AP your main goal here?
 


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#10 Napp

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Posted 24 October 2021 - 02:23 PM

Well, I mostly want the equatorial mount, and 8" seems good for getting some nice details in planets. And visual astronomy and manual tracking seems more fun with with an eq mount than my twitchy motorized alt az mount.

I'll leave the astrophotography advice to more knowledgable folks than me.  However, I do want to address your comment "...visual astronomy and manual tracking seems more fun with with an eq mount than my twitchy motorized alt az mount."  A twitchy mount is bad for visual and photography.  However, IMHO a good alt-az mount is superior to an eq mount for visual.  Why?  an alt-az mount keeps the eyepiece in more comfortably accessed positions than an eq mount.  With reflectors you sometimes need to rotate the tube on an eq mount to reach the eyepiece with your eye.  Refractors on an eq mount can place the eyepiece so low when pointed high that you may have trouble getting your head low enough unless you have a tall pier extension for the mount.  Even SCT's on an eq mount can put the eyepiece in awkward to reach positions.  How do I know?  I have had all these combinations.  I still mount refractors and an SCT on an eq mount to dabble with astrophotography.  But I now have a sturdy manual alt-az mount that accomodates my refractors quite well.  I now mostly use my alt-az mounted 10 inch or 16 inch reflectors (DOB's) or my 127mm ED refractor or 60mm Coronado SolarMax II on an alt-az manual mount for visual work.  Nice easy setup and comfortable to reach eyepiece positions.


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#11 bobzeq25

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Posted 24 October 2021 - 07:07 PM

bobzeq25 is spot on.  But if you're really bent on larger aperture and going deep, then a 6" RC (Ritchey-Chrétien Telescope) would do the trick.  At 1370fl and weighting in at 12lb it's much more manageable then a SCT with no coma up to a APS-C sensor.   The focuser on them is just ok for a DSLR.  But if you're thinking of adding on a filter-wheel ect then it will require an upgrade.  It's also difficult to attach a EAF (Electronic Auto Focuser) with the standard focuser.

Cheers!  
 

Yeah, right.  (NOT)

 

I, paying attention to people here, started with a 66mm refractor.  After a few months I was cranking out some decent images, decided (fool I) I was ready for a 6RC.

 

It was like stepping off a cliff.  Brought my progress as an imager to a screeching halt for months.  Part of the solution was a $2500 CEM60 mount, at least that was a good move.

 

Learning.  Doing.  Two different things.

 

If your goal is to go deep and image small DSOs with a big scope, you'll reach it faster/better/cheaper if you start with a small scope and widefield imaging.

 

When I did get the 6RC working on the CEM60 I ran into the focuser issue.  The scope, which had taken many hours to collimate, lost collimation when pointed in different directions.  Some people solve it with a Moonlight focuser.  Costs more than the scope.  I bought a nice 3.7 inch rack and pinion focuser.

 

It came attached to a TS130mm F7.  <smile>


Edited by bobzeq25, 24 October 2021 - 07:15 PM.

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#12 Mitrovarr

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Posted 24 October 2021 - 07:19 PM

I'd also suggest that if you try to start deep sky astrophotography, it helps to avoid starting out with a competitive mindset. There is no reason to expect you will be able to product images competitive with experienced APers with equipment 10x as expensive as yours. Don't expect that from yourself. The truth is, it's pretty  easy to just stick a camera on a telescope, put it on a suitable mount, and get pretty pictures that will impress anyone other than a seasosed AP'er. You'll just have to deal with the fact that the stars might be slightly streaked or something minor and stupid like that. The general public can't even tell if your images were autoguided or not.

 

I feel like everyone makes deep sky astrophotography out to be massively more difficult than it actually is.


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#13 Borodog

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Posted 24 October 2021 - 07:31 PM

bobzeq25 is spot on.  But if you're really bent on larger aperture and going deep, then a 6" RC (Ritchey-Chrétien Telescope) would do the trick.  At 1370fl and weighting in at 12lb it's much more manageable then a SCT with no coma up to a APS-C sensor.   The focuser on them is just ok for a DSLR.  But if you're thinking of adding on a filter-wheel ect then it will require an upgrade.  It's also difficult to attach a EAF (Electronic Auto Focuser) with the standard focuser.

Cheers!  
 

A C8 with f/6.3 reducer/corrector comes in at 1280mm and is coma free.



#14 sevenofnine

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Posted 24 October 2021 - 07:36 PM

The Deep-Sky Imaging Primer by Charles Bracken was recommended by an AP knowledgeable member. All your AP questions answered here. Best of luck to you! waytogo.gif


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#15 Branithar

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Posted 25 October 2021 - 09:46 AM

They sell newtonians specifically made for astrophotography now. They're really fast and the focuser, etc. are designed to for that purpose. They're also cheap.

Keep in mind you will need a huge and expensive mount to do AP with an 8" scope.

Are large newtonian telescopes designed to easily view stuff that is high up in the sky, at apogee? I don't want to have to take a ladder along, to see stuff. Cassegrain telescopes might be a little easier to see things at apogee. Cassegrain telescopes tend to have longer focal lengths and higher magnification, and are about f/10 (rather than around f/5 for newtonians), but I'm planning on mainly using it for visual and planetary photography. Would a cassegrain & focal reducer do the trick if I want to photograph a nebula or Andromeda?

I've been using an alt az 5" Maksutov Cassegrain for a few years, and I want something with more solid tracking and less twitchy movement: when I use my barlow lens, I have to push people out of the way and re-find planets, and hurry them back to the eyepiece before the object is gone.



#16 gnowellsct

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Posted 25 October 2021 - 10:19 AM

Are large newtonian telescopes designed to easily view stuff that is high up in the sky, at apogee? I don't want to have to take a ladder along, to see stuff. Cassegrain telescopes might be a little easier to see things at apogee. Cassegrain telescopes tend to have longer focal lengths and higher magnification, and are about f/10 (rather than around f/5 for newtonians), but I'm planning on mainly using it for visual and planetary photography. Would a cassegrain & focal reducer do the trick if I want to photograph a nebula or Andromeda?
I've been using an alt az 5" Maksutov Cassegrain for a few years, and I want something with more solid tracking and less twitchy movement: when I use my barlow lens, I have to push people out of the way and re-find planets, and hurry them back to the eyepiece before the object is gone.


You're trying to do an awful lot of things with one telescope and the problems you are raising are systemic and go to Total engineering of the system including its mount.

Newtonians tend to be inconvenient to use on an equatorial mount. If you have a very low tripod it helps keep the eyepiece in a reachable position. If you have a short focal ratio it helps keep the eye piece in a usable position so long as you don't choose an aperture which makes the tube long even though the focal ratio is short. I ultimately gave up on my 10-in f6 Newtonian. It was nearly impossible to get into the car and a chore to set up and difficult to operate. Newtonian designs make much more sense on alt-azimuth mounts.

Pretty picture photography is best done with refractors as has been indicated above. There are certain research projects like measuring changes in light intensity of stars or looking for supernovae where not really interested in a pretty picture but inaccurate measurements. Now you're talking about bolting on a camera and leaving it in place so it doesn't shift around and you don't worry about where the eyepiece is because it doesn't matter where the camera is going.

If you want wide fields and pretty pictures and you want to use an sct then the edge HD series by Celestron is something you might want to look at. This is a conversation you should have with starizona in Arizona. You can use the edge at extremely short focal lengths removing the secondary. You can use it as a normal SCT by putting the secondary back in.

As far as your problems go with tracking and stability of the mount this is a core issue for anyone who likes German equatorials. I use a lasmandi g11 with a c8 and a side-mounted refractor. If you had the edge HD c8 and a side-mounted refractor on a g11 you would have a lot of toys that meet your requirements. Refractor could be mounted by itself to give you experience doing wide field astrophotography. Once you know the ropes you could use your edge hd c8 for wide fields at larger aperture. By inserting the secondary mirror in the edge hd c8 you would have a telescope that could do great planetary imaging.

A c8 in normal configuration is a great all-around scope for general visual observing purposes and if you have a 3-in refractor to go with it then you have a highly flexible combination when they are mounted together on the same mount.

If you are a budget limited then get the g11 and then choose whether you want to start with planets or wide fields. For planets get a c8. And I mean any c8. Pick one up for $400 used. For wide field get a refractor. Don't scrimp on the refractor. I would stick with skywatcher among the imports. But I don't stick with skywatcher I have a cff 92 mm among other refractors. In my view refractors are not really made for scrimping.

Getting a good mount should have priority because on a good mountain you can put a wide variety of optical tubes.

If you are feeling cost constrained and want visual uses as well then a used c8 on a losmandy g11. Get a webcam for a couple hundred bucks and you will be in business for planetary imaging.

Spend 6 months doing the moon and the planets and see where you get. If you like image processing and data acquisition then think about getting the refractor. The art of widefield refractor imaging is very very different. But starting with a good mount, you will have a friend vital to the Enterprise.

All the varied options you are putting on the table here are not cheap especially if you say you want to do visual and you want to steady amount and you want enough accuracy to do astrophotography and you can't decide between planets and pretty wide field photography.

You would be wise to figure out what it is you want at least for the next year or two. Myself, I have the optics and mounts I need to do astrophotography but I own no cameras. I don't want to drive myself crazy.

#17 Mitrovarr

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Posted 25 October 2021 - 12:00 PM

Are large newtonian telescopes designed to easily view stuff that is high up in the sky, at apogee? I don't want to have to take a ladder along, to see stuff. Cassegrain telescopes might be a little easier to see things at apogee. Cassegrain telescopes tend to have longer focal lengths and higher magnification, and are about f/10 (rather than around f/5 for newtonians), but I'm planning on mainly using it for visual and planetary photography. Would a cassegrain & focal reducer do the trick if I want to photograph a nebula or Andromeda?
I've been using an alt az 5" Maksutov Cassegrain for a few years, and I want something with more solid tracking and less twitchy movement: when I use my barlow lens, I have to push people out of the way and re-find planets, and hurry them back to the eyepiece before the object is gone.

Imaging newtonians have pretty bad ergonomics for viewing. You can get rotating rings to make it tolerable.

Despite the bad rep they get, lots of people use SCTs for imaging. You can get an Edge with a focal reducer which is a decent long FL imaging platform, or get a hyperstar for it and have an interesting super-fast large aperture platform. These are not easy to use for deep sky AP but people make them work. This is an expensive route to travel, since you need a huge costly mount and Edge scopes aren't cheap, nor are their focal reducers, and hyperstars add at least another thousand.

Large SCTs are also some of the very best platforms for planetary imaging. Basically, the bigger the better. A 14" SCT is almost stereotypical as the standard hard-core planetary imaging platform.

After some more thought, I suggest the following - get a nice bit chunky EQ mount like an EQ-6R or even bigger, and get a big SCT like a 9.25 or 11. It'll be great for visual and planetary AP. Then, if you ever want to do deepsky AP, buy a nice little apo for $500-1000 and use that on your fancy big mount, it'll work great and be cheaper than trying to make the SCT work for it, plus about a billion times easier.

Edited by Mitrovarr, 25 October 2021 - 12:03 PM.


#18 bobzeq25

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Posted 25 October 2021 - 02:21 PM

Imaging newtonians have pretty bad ergonomics for viewing. You can get rotating rings to make it tolerable.

Despite the bad rep they get, lots of people use SCTs for imaging. You can get an Edge with a focal reducer which is a decent long FL imaging platform, or get a hyperstar for it and have an interesting super-fast large aperture platform. These are not easy to use for deep sky AP but people make them work. This is an expensive route to travel, since you need a huge costly mount and Edge scopes aren't cheap, nor are their focal reducers, and hyperstars add at least another thousand.

Large SCTs are also some of the very best platforms for planetary imaging. Basically, the bigger the better. A 14" SCT is almost stereotypical as the standard hard-core planetary imaging platform.

After some more thought, I suggest the following - get a nice bit chunky EQ mount like an EQ-6R or even bigger, and get a big SCT like a 9.25 or 11. It'll be great for visual and planetary AP. Then, if you ever want to do deepsky AP, buy a nice little apo for $500-1000 and use that on your fancy big mount, it'll work great and be cheaper than trying to make the SCT work for it, plus about a billion times easier.

I'll agree with the final recommendation.  Two scopes is definitely a good way to go.  These things are all so different.

 

But, there's also a great example here of not making the learning/doing difference clear.

 

SCTs do not have a bad rep with me for doing imaging.  They're maybe the worst scope for a new beginner to try to learn imaging with.


Edited by bobzeq25, 25 October 2021 - 02:23 PM.


#19 Mitrovarr

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Posted 25 October 2021 - 02:29 PM

They don't have a bad rep for me either, and I do sometimes think about getting a nice Edge scope with reducer and possibly a hyperstar. Although I fear the age ranges where I can afford such a setup and still be young enough to lift it may not overlap much.

#20 Jared

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Posted 25 October 2021 - 08:05 PM

I've seen 8" reflectors that range from $1,500 to $4,000, and range from f/15 to f/2. I have a color planetary camera and DSLR, and eventually I'll want to get a cooled deep space camera. What telescopes provide a lot of bang-for-your-buck, and do well with deep space astrophotography?

If I had to pick one “do it all” eight inch telescope for everything from deep sky imaging to planetary visual observing it would be a Celestron Edge 8”. No, it’s not easy to learn deep sky imaging with it, but it is possible as long as your mount is up to the task. It’s compatible with Hyperstar if you go that way. It’s a great visual scope. That’s what I’d recommend given your requirements.

 

Keep in mind, what others have said about starting imaging with a smaller refractor is a good idea. It’s a much easier way to learn deep sky astrophotography. I’d probably recommend adding that to your current scope instead of making a switch to a “do it all” scope. But if I had to pick one “do it all” it would be the Edge. Hard to learn on, but a very good visual and imaging scope.




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