6 replies to this topic

[jroozee]

** cross posted on r/AskAstrophotography **

 

Does anyone have a recommendation for a decent scope for a DSO astrophotography that is lightweight enough for my AM5N mount and is decent quality?

 

I currently have a Orion 104mm EON ED-X2 scope with field flattener but something like M51 is just too small to image effectivly. 

 

I was considering the Celestron XLT EdgeHD 8 but I read somewhere that a Newtonian is a better route to go. 

 

I currently use a Nikon D850 but I have a ASI2600MC arriving soon.

 

My budget is around $2k but I would go higher if it's worth it. I would like something that is a good companion to my 104mm f/6.25 for different use cases. I would also love if I could find a 10-12" instead but I hear they're just too heavy, but I have seen some people do it on

a AM5N.

 

[TerryD1]

The AM5N is plenty capable of carrying long focal lengths but if you can only have one scope it will limit your field of view.  I regularly image with an 840mm fl scope on an AM3 with a counterweight unless it’s my longest focal length of the night.  Then it goes on the AM5 with a smaller scope on the AM3.  I’ve done quite a bit of imaging with an RC8 at 1600mm on the AM5 with great success.  It’s for sale btw.  If you want that reach your AM5N will work very well but do some experimenting with different focal lengths on Telescopius to determine what will be the best fit for the targets you want to pursue.

[Andros246]

** cross posted on r/AskAstrophotography **

Does anyone have a recommendation for a decent scope for a DSO astrophotography that is lightweight enough for my AM5N mount and is decent quality?

I currently have a Orion 104mm EON ED-X2 scope with field flattener but something like M51 is just too small to image effectivly.

I was considering the Celestron XLT EdgeHD 8 but I read somewhere that a Newtonian is a better route to go.

I currently use a Nikon D850 but I have a ASI2600MC arriving soon.

My budget is around $2k but I would go higher if it's worth it. I would like something that is a good companion to my 104mm f/6.25 for different use cases. I would also love if I could find a 10-12" instead but I hear they're just too heavy, but I have seen some people do it on
a AM5N.

My question is why is a 100mm refractor too small for m51? it’s almost seeing limited (assuming have average seeing with 3.76um pixel size) you can only probably realistically gain about 10-20 percent more detail from resolving power by getting something larger.

Edited by Andros246, 16 May 2025 - 09:35 PM.

[TerryD1]

My question is why is a 100mm refractor too small for m51? it’s almost seeing limited (assuming have average seeing with 3.76um pixel size) you can only probably realistically gain about 10-20 percent more detail from resolving power by getting something larger.

I think the OP is referring more to the size of the object in the frame.  In a 100mm scope M51 is pretty tiny on an APS-C sensor.

[TelescopeGreg]

For scale, below is M51 with a 130mm f/7 (so, 910mm focal length) telescope and the ASI2600MC camera.  80 minutes of 4 minute exposures at a dark site.  No reducer / flattener was used, and the image is pretty much the entire camera field of view (a few dozen pixels trimmed around the edges for stacking cleanup).

 

On the other end of the scale, I can just fit the full Moon in the field of view.  M31 (Andromeda Galaxy), the Heart Nebula, and a number of other popular targets do NOT fit.  Andromeda actually looked pretty good cropped to the frame diagonal, but I needed a 2x2 mosaic for the Heart Nebula.  Bottom line, there is no single "best" telescope focal length.  I really like my scope, but it's more for the optics than the focal length.

 

The mount I am using is an AVX, which is less capable than the AM5, though you would want to use a counterweight with the AM5 with a scope such as this.  Autoguider was using a 60mm f/4.6 guide scope and ASI174mm Mini camera.  All-in, the moving stuff comes in at just over 26 lbs.

 

[Sacred Heart]

** cross posted on r/AskAstrophotography **

 

Does anyone have a recommendation for a decent scope for a DSO astrophotography that is lightweight enough for my AM5N mount and is decent quality?

 

I currently have a Orion 104mm EON ED-X2 scope with field flattener but something like M51 is just too small to image effectivly. 

 

I was considering the Celestron XLT EdgeHD 8 but I read somewhere that a Newtonian is a better route to go. 

 

I currently use a Nikon D850 but I have a ASI2600MC arriving soon.

 

My budget is around $2k but I would go higher if it's worth it. I would like something that is a good companion to my 104mm f/6.25 for different use cases. I would also love if I could find a 10-12" instead but I hear they're just too heavy, but I have seen some people do it on

a AM5N.

Hello jroozee,

 

Welcome to CN.

 

If you are talking about a 10" Newtonian at F4, Skywatcher Quatro for example, this is listed at 36.5 pounds.  The AM5N is listed for 33 pounds without CW and 44 pounds with CW.  

 

On paper it looks like it would work, however I don't think it is as easy as it looks on paper. Yes CW will be needed, but more will have to be done, I think.   That scope is 36" long and roughly 11" in diameter, quite large. That is where the problem lies.  Being large.  I do not own a scope like that nor an AM5 mount, but I am thinking this scope will have to be somewhat balanced front to rear in the Dec saddle.  Roughly finding the balance point on a bench using a round object like a small pipe or maybe a pencil and putting that in the center of the saddle.  Next is a pier extension or two extensions for clearance of the tripod legs.  The ZWO CF tripod may need to be upgraded to a more stout tripod as well, don't know. Also you will most likely need to anchor the tripod to the ground, a turnbuckle at each leg.  Looking / needing stability here.   Don't forget about wind, 11" x 36"  object can catch some wind in my opinion.

 

The other side of the story is tracking error and image scale.  ZWO 2600 and 1000mm you will have to guide under .78. Another reason stability is needed.
 

Going from 100mm to 254mm in diameter is huge, a big jump in resolving power and brightness,  650mm to 1000mm is a jump up but not as big as the diameter jump.  My opinion.

 

My recommendation,  knowing what OTA you want - find owners with that scope / mount ask them the hard questions.  Hopefully some people who have these scopes and mounts will chime in and tell you a thing or two.

 

Another thing to try, when you get your 2600 camera, crop the image. See how you like it.

 

My opinion and thoughts,   Joe

Edited by Sacred Heart, 17 May 2025 - 02:59 AM.

[sturgis_star_guy]

If you haven't done so already, astronomy.tools will help you look at the field of view for most telescope and camera options.  M51 is small in my 6" Newtonian, but M101 fits perfectly.  My point is that chasing focal length may not always be what you want, which I think was also the point made by others here already.  Going big also brings on other issues, such as a need for more precise guiding.  A big 10" Newtonian acts like a sale in the wind and longer refractors are not only expensive but there's a lot of weight away from the center axis of the mount.  I have found that capturing multiple objects within one image is also satisfying, although I sacrifice the close-up detail.  The Markarian Chain would be a perfect example of something that can't be caught with a long focal length.  Good luck with your search.