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Refractor Recommendations

Equipment Astrophotography Refractor
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5 replies to this topic

#1 Nichols89ben

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Posted 16 April 2024 - 06:29 PM

Hi everyone! I've been enjoying astrophotography with my current setup: RedCat 51, Canon T7i, and Star Adventurer GTI. While I love the wide-field shots, I'm finding the 250mm focal length limiting for galaxy season. I'm considering a refractor around $1000, aiming for a 750-800mm focal length, but I'm concerned about exceeding my GTI mount's weight capacity. I'd prefer not to upgrade the mount just yet. Any recommendations for a scope that fits these criteria? Thanks for your help!



#2 drmikevt

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Posted 16 April 2024 - 06:53 PM

With your mount, you're very limited in your options.  I think the biggest you can go, once you add an imaging train, would be something like the WO Zenithstar 81, which is a very decent scope, but not a galaxy scope (except for M31, ofc).  For a good galaxy scope, you'd want something 800-1000mm at least and that is just not possible with your mount.

 

The scope that fits your specs is the Askar 103 triplet, but its 10.5lbs without any accessories and you mount can only handle 11lbs.


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#3 BlueMoon

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Posted 16 April 2024 - 07:10 PM

The advertised max payload limit for your mount is 11 lbs. AP generally limits payload to 1/2 to 2/3 of the max. So, let's say 5.5 lbs to 8 lb all up. Off hand I'd say you'll have some difficulty finding a light enough refractor at the f/l you want that will be in that weight range. Cheers.


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#4 Robert7980

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Posted 16 April 2024 - 07:34 PM

Refractors are the most expensive design per inch of aperture so when on a budget they really aren’t the best choice. What you should look at is the 6 inch class of mirror based scopes, but even if you meet your budget you’re going to have issues guiding and handling the weight with your current mount, so you really need to upgrade the mount 1st… Hate to have nothing but bad news, but I think that’s the situation your in. I don’t think there is a solution that meets you’re criteria that is going to make you happy… 



#5 bobzeq25

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Posted 16 April 2024 - 08:01 PM

Hi everyone! I've been enjoying astrophotography with my current setup: RedCat 51, Canon T7i, and Star Adventurer GTI. While I love the wide-field shots, I'm finding the 250mm focal length limiting for galaxy season. I'm considering a refractor around $1000, aiming for a 750-800mm focal length, but I'm concerned about exceeding my GTI mount's weight capacity. I'd prefer not to upgrade the mount just yet. Any recommendations for a scope that fits these criteria? Thanks for your help!

Forget the weight capacity.  The longer focal length (700-800) will do you in first, because it magnifies the (large) tracking error of that inexpensive mount.

 

Want to image small galaxies?  The FIRST thing you need is a better mount.

 

You could go somewhat larger than the 51.  But this is the BIGGEST scope I'd recommend with that mount.  And, if you're not already, you'll definitely need to autoguide.

 

https://agenaastro.c...aph-fra400.html

 

Something in between could work.  Nothing larger.

 

Look at the first review of the FRA400, and the setup (also pictured below).  That's an AM3 mount, $1900.  If your scope costs more than your mount, you're making a mistake.

 

askar 400 setup.jpg


Edited by bobzeq25, 16 April 2024 - 08:12 PM.


#6 Oort Cloud

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Posted 16 April 2024 - 08:09 PM

Galaxies and star trackers aren't compatible, unless you're talking about Andromeda or are okay with imaging wide fields of tiny galaxies, like Markarian's Chain.

Anything else involves more focal length than your mount can handle, which is realistically about 300-400mm, provided you autoguide.
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