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telescope for small galaxies

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#1 slamdunk

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Posted 17 April 2021 - 11:42 AM

Hi everyone, I wanted to ask you which telescope you recommend that can be used to photograph small galaxies (for example M88, M90).

 

Thank you so much!!!


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#2 bobzeq25

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Posted 17 April 2021 - 11:53 AM

I _strongly_ suggest you read this thread, carefully.  I cannot possibly emphasize that enough.

 

https://www.cloudyni...with-small-fls/

 

One point, relatively minor, compared to other issues.

 

You will not be imaging small galaxies with an EQM-35 mount, even one working perfectly for an EQM-35.

 

Think EQ6-R, absolute minimum.   $1600.  My TS 130 (discussed in another thread of yours) sits on a CEM-60.  $2500.  It's not overkill.

 

The two most important things for imaging small galaxies do not include the scope.

 

A good mount.

 

Substantial experience with large targets.


Edited by bobzeq25, 17 April 2021 - 11:54 AM.

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#3 slamdunk

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Posted 17 April 2021 - 12:12 PM

I _strongly_ suggest you read this thread, carefully.  I cannot possibly emphasize that enough.

 

https://www.cloudyni...with-small-fls/

 

One point, relatively minor, compared to other issues.

 

You will not be imaging small galaxies with an EQM-35 mount, even one working perfectly for an EQM-35.

 

Think EQ6-R, absolute minimum.   $1600.  My TS 130 (discussed in another thread of yours) sits on a CEM-60.  $2500.  It's not overkill.

 

The two most important things for imaging small galaxies do not include the scope.

 

A good mount.

 

Substantial experience with large targets.

Thanks,  I am just thinking at the time to buy a mount according to the telescope (one of my options is precisely the eqr6, my only doubt to buy it is the weight to transport it), but what I would like to know is which telescope would serve me for that type of photos



#4 Cali

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Posted 17 April 2021 - 12:32 PM

If you are new to the hobby but have not come into an inheritance and are into Astro Photography, check out this.

 

ASTRO-TECH AT102ED 4" F/7 ED REFRACTOR OTA

 

Let the wars begin ...

 

-Cal


Edited by Cali, 17 April 2021 - 12:36 PM.

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#5 slamdunk

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Posted 17 April 2021 - 12:46 PM

If you are new to the hobby but have not come into an inheritance and are into Astro Photography, check out this.

 

ASTRO-TECH AT102ED 4" F/7 ED REFRACTOR OTA

 

Let the wars begin ...

 

-Cal

thanks, I've been in the hobby for two years, what I want is a telescope for small galaxies, with a 102 I don't think I will achieve that (in fact I am looking to buy a 102, but for another use)


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#6 ravenhawk82

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Posted 17 April 2021 - 12:56 PM

What sort of mount do you have? That'll be a limiting factor long before most telescopes. The small features of galaxies means that your mount needs to be guiding very well to get good results.

Once you have a mount, more important than the scope itself is the angular resolution of your sensor and telescope together. 1 arcsecond pixels are 1 arcsecond pixels, whether they're large and paired with a long focal length or small and paired with a short focal length. The bigger pixels just mean you can collect more light in them leading to a better SNR in your subframes, but small pixels on a smaller telescope will be cheaper and easier to make work, all other things considered. So if you already have a camera that'll figure into what scope you want. 

Without knowing more, I'd start by looking at something around 1000mm of focal length. At that point, there's going to be a camera that will pair well with it to maximize the resolving power of both the scope and the camera. The specific design of the scope doesn't matter all that much though as the ensuing tradeoffs are all matters of preference. For example, a newtonian is the cheapest way to get good resolving power but also requires a coma corrector for stars to look good, while an apocromatic refractor can give you killer results out of the box at a much greater cost than the newt and coma corrector. 

If you already have a camera and mount let us know and we can provide better tailored suggestions :)


I would disagree that getting good results imaging galaxies requires substantial experience with large targets though... Large targets are easier to get good results with quicker, but the things that yield good results apply to everything. It's fine to start with small stuff (My first astrophotography experiences were with an AT6RC), just know that you're going to have some smudgy details and bloated stars while you get the process down. That's just part of learning the craft.



#7 WadeH237

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Posted 17 April 2021 - 01:00 PM

If you have a sufficient mount (and, as Bob says, a good foundation of experience), I think that an 8" scope makes a fine galaxy instrument.  It could either be an SCT or and RC.  I have used both, and prefer my EdgeHD 8 over the GSO RC scopes.  This is due to the mechanical quality and collimation requirements for the RC scopes.  If it were possible to transplant the GSO optics into something with significantly better mechanical quality, I would probably change my answer.

 

The nice thing about the 8" SCTs and RCs is that unless you have exceptional seeing, they are pretty much sky limited in terms of resolution.  What that means is that you can get similar results to a much larger instrument at the cost of longer total exposure times.  As you go up in size, you'll still be sky limited for resolution, but you can get faster optics to reduce imaging time (look up etendue to understand why).  Of course, as you start going bigger than an 8" SCT, the cost, weight and mount requirements go up - pretty much exponentially.

 

Regarding the suggestion above for the AT102ED, I have one and would not recommend it for imaging.  It's one of my favorite visual instruments due to it's grab-and-go characteristics.  But its color correction is a weak point for imaging.  Also, at least with my example, the focuser has trouble with a heavy instrument package and tends to slip a bit.  For manual focusing, it's no big deal, but you can't automate focus well because it's not repeatable enough.


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#8 slamdunk

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Posted 17 April 2021 - 03:26 PM

What sort of mount do you have? That'll be a limiting factor long before most telescopes. The small features of galaxies means that your mount needs to be guiding very well to get good results.

Once you have a mount, more important than the scope itself is the angular resolution of your sensor and telescope together. 1 arcsecond pixels are 1 arcsecond pixels, whether they're large and paired with a long focal length or small and paired with a short focal length. The bigger pixels just mean you can collect more light in them leading to a better SNR in your subframes, but small pixels on a smaller telescope will be cheaper and easier to make work, all other things considered. So if you already have a camera that'll figure into what scope you want. 

Without knowing more, I'd start by looking at something around 1000mm of focal length. At that point, there's going to be a camera that will pair well with it to maximize the resolving power of both the scope and the camera. The specific design of the scope doesn't matter all that much though as the ensuing tradeoffs are all matters of preference. For example, a newtonian is the cheapest way to get good resolving power but also requires a coma corrector for stars to look good, while an apocromatic refractor can give you killer results out of the box at a much greater cost than the newt and coma corrector. 

If you already have a camera and mount let us know and we can provide better tailored suggestions smile.gif


I would disagree that getting good results imaging galaxies requires substantial experience with large targets though... Large targets are easier to get good results with quicker, but the things that yield good results apply to everything. It's fine to start with small stuff (My first astrophotography experiences were with an AT6RC), just know that you're going to have some smudgy details and bloated stars while you get the process down. That's just part of learning the craft.

Thanks, I currently have an eqm-35, but possibly next week I will buy a new one with a higher capacity (I am between the heq5 pro and the eq6r. I am more inclined to the eq6r, but I worry a little about the weight to carry it each time to the roof of my building or to the field). The camera I use is a modified nikon d5600 and I have an off-axis guide with an asi290mc for tracking.

 

Although I know it is not for deep sky, I have been able to get more than decent results from some galaxies with a skywatcher mak 127, a good tracking makes miracles


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#9 slamdunk

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Posted 17 April 2021 - 03:38 PM

If you have a sufficient mount (and, as Bob says, a good foundation of experience), I think that an 8" scope makes a fine galaxy instrument.  It could either be an SCT or and RC.  I have used both, and prefer my EdgeHD 8 over the GSO RC scopes.  This is due to the mechanical quality and collimation requirements for the RC scopes.  If it were possible to transplant the GSO optics into something with significantly better mechanical quality, I would probably change my answer.

 

The nice thing about the 8" SCTs and RCs is that unless you have exceptional seeing, they are pretty much sky limited in terms of resolution.  What that means is that you can get similar results to a much larger instrument at the cost of longer total exposure times.  As you go up in size, you'll still be sky limited for resolution, but you can get faster optics to reduce imaging time (look up etendue to understand why).  Of course, as you start going bigger than an 8" SCT, the cost, weight and mount requirements go up - pretty much exponentially.

 

Regarding the suggestion above for the AT102ED, I have one and would not recommend it for imaging.  It's one of my favorite visual instruments due to it's grab-and-go characteristics.  But its color correction is a weak point for imaging.  Also, at least with my example, the focuser has trouble with a heavy instrument package and tends to slip a bit.  For manual focusing, it's no big deal, but you can't automate focus well because it's not repeatable enough.

ok, thank lot!!, with the weight of the EdgeHD 8, even I could opt for a heq5 instead of the eq6r, which I like because of the weight to transport. I will see that option.

About a 102mm refractor, what do you think of the Explore scientific 102 ED (FCD100) carbon fiber for astrophotography? (not a replacement for the EDGE HD8, I mean as an upgrade from a 72ED refractor)



#10 Cali

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Posted 17 April 2021 - 03:44 PM

 

Although I know it is not for deep sky, I have been able to get more than decent results from some galaxies with a skywatcher mak 127, a good tracking makes miracles

Yeah!   The 127mm Mak.  A most underrated scope.

 

Seems everyone who owned one rues the day they let it go.

 

- Cal



#11 ravenhawk82

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Posted 17 April 2021 - 03:54 PM

Thanks, I currently have an eqm-35, but possibly next week I will buy a new one with a higher capacity (I am between the heq5 pro and the eq6r. I am more inclined to the eq6r, but I worry a little about the weight to carry it each time to the roof of my building or to the field). The camera I use is a modified nikon d5600 and I have an off-axis guide with an asi290mc for tracking.

 

Although I know it is not for deep sky, I have been able to get more than decent results from some galaxies with a skywatcher mak 127, a good tracking makes miracles

Sounds like a good start! I'd definitely recommend the EQ6 over the EQ5 for stability and future proofing (My pre-belt Atlas handles everything from an AT80ED to a 10"SCT at the heavier end). You might also want to consider the CEM40 from iOptron. Similar capacity and performance with a lighter weight owing to its design, so moving it might be easier for you. With that camera, I'd target a focal length of around 900-1000mm, give or take a smidge. That'll put you at around 0.8-0.9 arcseconds per pixel. I like to err on the side of oversampling a bit for nights when the seeing is exceptional  and my polar alignment is extra good so this is a pretty good angular resolution to shoot for in my opinion. If you decide to go that route you'll want something with an aperture of ~5" or more, otherwise the scope's resolving power won't be able to keep up. Which way you achieve this depends on how much you want to spend. I get good results with my AT6RC, but it's a fiddly scope. The 8"Edge with a focal reducer would be a good choice IMO. More oversampling, but again, if the stars look bloated you can downscale your image a bit. 24MP gives you a lot to work with.

Since you have a 127mm mak, it may be worth sticking a focal reducer on it and seeing what you can manage. It's not ideal, but it'd be a great way to get started without spending any more money and getting the experience to use a more suitable tool to its full potential. I'm not very familiar with that scope though, so I'll let someone with a better understanding of Maks chime in with how well that might work. You'd likely at least need a guide scope due to the smaller image circle with a reducer.


Edited by ravenhawk82, 17 April 2021 - 03:56 PM.

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#12 slamdunk

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Posted 17 April 2021 - 05:15 PM

Yeah!   The 127mm Mak.  A most underrated scope.

 

Seems everyone who owned one rues the day they let it go.

 

- Cal

yes, I am really happy with that telescope, it has given me a lot of satisfaction even in deep sky, although most of them discard it for that


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#13 slamdunk

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Posted 17 April 2021 - 05:25 PM

Sounds like a good start! I'd definitely recommend the EQ6 over the EQ5 for stability and future proofing (My pre-belt Atlas handles everything from an AT80ED to a 10"SCT at the heavier end). You might also want to consider the CEM40 from iOptron. Similar capacity and performance with a lighter weight owing to its design, so moving it might be easier for you. With that camera, I'd target a focal length of around 900-1000mm, give or take a smidge. That'll put you at around 0.8-0.9 arcseconds per pixel. I like to err on the side of oversampling a bit for nights when the seeing is exceptional  and my polar alignment is extra good so this is a pretty good angular resolution to shoot for in my opinion. If you decide to go that route you'll want something with an aperture of ~5" or more, otherwise the scope's resolving power won't be able to keep up. Which way you achieve this depends on how much you want to spend. I get good results with my AT6RC, but it's a fiddly scope. The 8"Edge with a focal reducer would be a good choice IMO. More oversampling, but again, if the stars look bloated you can downscale your image a bit. 24MP gives you a lot to work with.

Since you have a 127mm mak, it may be worth sticking a focal reducer on it and seeing what you can manage. It's not ideal, but it'd be a great way to get started without spending any more money and getting the experience to use a more suitable tool to its full potential. I'm not very familiar with that scope though, so I'll let someone with a better understanding of Maks chime in with how well that might work. You'd likely at least need a guide scope due to the smaller image circle with a reducer.

Thank you very much for your advice. I saw the CEM40 and I loved it, although it is a little more expensive than the eq6r, it is much lighter !! sadly I have not been able to find a page that has it in stock at the moment, but if I find one I bought that one.

 

About my mak 127, I have tried some reducers, but they do not work well in photography. Apparently that tube does not have a specific reducer

 

About the tube for photographing small galaxies, I am thinking between the one recommended by WadeH237 (EdgeHD8) and the mak 180



#14 ravenhawk82

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Posted 17 April 2021 - 05:34 PM

Thank you very much for your advice. I saw the CEM40 and I loved it, although it is a little more expensive than the eq6r, it is much lighter !! sadly I have not been able to find a page that has it in stock at the moment, but if I find one I bought that one.

 

About my mak 127, I have tried some reducers, but they do not work well in photography. Apparently that tube does not have a specific reducer

 

About the tube for photographing small galaxies, I am thinking between the one recommended by WadeH237 (EdgeHD8) and the mak 180

I'd definitely go for the HD8 if photography is the goal. Maks have much slower focal ratios that make for a well corrected view at the eyepiece but very long exposure times. You'll already want a focal reducer for the HD8 (Celestron makes an F7 reducer for this purpose) to pull it down to a more usable focal length and faster focal ratio. 

Regarding the CEM40, if you're not in a hurry they pop up from time to time. I just ordered a CEM70 after spending a few weeks keeping an eye out for one to come in stock somewhere (Thanks Astronomics!).



#15 slamdunk

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Posted 17 April 2021 - 05:55 PM

I'd definitely go for the HD8 if photography is the goal. Maks have much slower focal ratios that make for a well corrected view at the eyepiece but very long exposure times. You'll already want a focal reducer for the HD8 (Celestron makes an F7 reducer for this purpose) to pull it down to a more usable focal length and faster focal ratio. 

Regarding the CEM40, if you're not in a hurry they pop up from time to time. I just ordered a CEM70 after spending a few weeks keeping an eye out for one to come in stock somewhere (Thanks Astronomics!).

Thanks friend, I will follow your advice with the telescope.
Regarding the mount, I will wait a couple of weeks to see if any cem40 appears (if I can hold that long). I appreciate a lot your help!!



#16 teashea

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Posted 17 April 2021 - 06:29 PM

I _strongly_ suggest you read this thread, carefully.  I cannot possibly emphasize that enough.

 

https://www.cloudyni...with-small-fls/

 

One point, relatively minor, compared to other issues.

 

You will not be imaging small galaxies with an EQM-35 mount, even one working perfectly for an EQM-35.

 

Think EQ6-R, absolute minimum.   $1600.  My TS 130 (discussed in another thread of yours) sits on a CEM-60.  $2500.  It's not overkill.

 

The two most important things for imaging small galaxies do not include the scope.

 

A good mount.

 

Substantial experience with large targets.

So true.  The mount is more important than the telescope.


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#17 teashea

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Posted 17 April 2021 - 06:32 PM

If you are new to the hobby but have not come into an inheritance and are into Astro Photography, check out this.

 

ASTRO-TECH AT102ED 4" F/7 ED REFRACTOR OTA

 

Let the wars begin ...

 

-Cal

If it is larger inheritance and you want the best then a Takahashi FSQ85EDX/EDP or its big brother the FSQ106EDX



#18 RichA

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Posted 17 April 2021 - 11:01 PM

Hi everyone, I wanted to ask you which telescope you recommend that can be used to photograph small galaxies (for example M88, M90).

 

Thank you so much!!!

Celestron 14.



#19 WadeH237

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Posted 18 April 2021 - 08:13 AM

...what do you think of the Explore scientific 102 ED (FCD100) carbon fiber for astrophotography?

I've never used one, so I don't have a first hand opinion on it.



#20 teashea

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Posted 18 April 2021 - 09:51 AM

You have so many options.  You can either spend a lot and purchase a first class system to start or start with a lesser system and grow it as you go along.


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#21 AhBok

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Posted 19 April 2021 - 12:24 PM

I use an EQ6R Pro mount and while heavy, the transportability of the mount is much better than many may think. You have to get away from the specs and find the ergonomics of the mount head are better than most mounts. I’m an average 70 year old and never even think about it’s weight. Unless you have serious back problem, etc., I do not think most would have difficulty with this mount and it is rock stable if you have a suitable load.

 

The average 4 year old weighs the same as the mount head.

 

To keep in line with the topic—I have a 6” RC for galaxies and am very pleased with it. Some do not like the smaller RCs, but if you do overload the focuser and use an auto focuser system like the ZWO, it can produce fine images of smaller galaxies, PNs, etc. I piggyback my 72mm on top of my RC6 for wide field and the EQ6R handles the load perfectly.


Edited by AhBok, 19 April 2021 - 12:32 PM.

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#22 slamdunk

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Posted 19 April 2021 - 08:43 PM

Thanks, I was looking but I could not find stock for the EQ6-R or the CEM40. What do you think of AZEQ6? It is the only similar one that I have found in stock, but I am not very sure about it


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#23 AhBok

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Posted 20 April 2021 - 07:12 PM

It is a fine mount for AP and visual. I went with the EQ6R Pro because I only use the mount for AP, so I saved a few bucks and they were plentiful at the time. Just make sure you get the AZEQ6 and not the AZEQ5 which is a lesser mount.



#24 slamdunk

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Posted 24 April 2021 - 05:10 PM

now I also found a cem40 in stock too, but with a 1.5 "tripod. I am in doubt whether to buy that or the AZEQ6, but I can't decide !!!. I have read comments that the CEM 40 is a roulette and if you have luck is good for you and if it is not a headache.

 

I love azeq6, but it scares me that it is too heavy to transport



#25 slamdunk

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Posted 27 April 2021 - 10:50 PM

hi everyone, i finally bought an AZEQ6 mount (it arrives in 3 weeks !!) , so the weight should no longer be a major obstacle for the telescope I choose.

 

It also already had an hercules off-axis guide for tracking, the ipolar for polar alignment, a Nikon D5600 and a zwo asi290 for tracking.

 

Now, about the telescope for small galaxies, and after seeing the options that have been recommended to me, I am among the following telescopes (although any other recommendation is welcome):

 

- Celestron C8-A (XLT) 8”

- Celestron Edge HD 8

- Celestron C9¼-A (XLT)

- ED 127 APO Explore Scientific FCD-100

- Sky-Watcher evostar 120 Ed APO

- Sky-Watcher evostar 150 Ed APO


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