12 replies to this topic

[Joey44]

I am looking for a recommendation for a second scope. I have a Nexstar 6 SE SCT and have enjoyed using it but are wishing for more FOV. Even with focal reducers I am limited to about ½ degree FOV. I view mostly in the spring/summer/fall in a bortle 3 zone. I would like something that would give me at least a 2 degree FOV for larger DSOs.
I want to be able to repurpose my current alt/az mount, so am looking for just an OTA. I am not interested in serious astrophotography, but would like to continue my short-exposure EAA with my ZWO ASI224MC camera and Sharpcap, and also like to take afocal photos with my cell phone though the eyepiece. All my eyepieces are 1.25 inch and I don’t plan to upgrade them.
I have been reading about refractors and it seems that maybe a refractor in the f/5 range might fit the bill. From what I have read the more expensive ones minimize chromatic aberration, but I don’t know much this might be an issue for my purposes.

So, my requirements:
• Compatible with my current mount, Celestron says the weight limit is 12 lbs.
• Be able to mount a dovetail on the side on the OTA so that it will orient properly in the mount fork arm and not be so long that it hits the mount and limits elevation too much (although I have no need normally above 70 degrees).
• Be able to use 1.25 inch eyepieces, handle my uncooled astrocamera.
• Give a FOV of 2 degrees or more with up to 32 mm. eyepieces.
• Chromatic aberration not terrible for my purposes
• Budget of $500

Thanks in advance for any useful info that the always helpful CN community can provide.

[Wildetelescope]

I am looking for a recommendation for a second scope. I have a Nexstar 6 SE SCT and have enjoyed using it but are wishing for more FOV. Even with focal reducers I am limited to about ½ degree FOV. I view mostly in the spring/summer/fall in a bortle 3 zone. I would like something that would give me at least a 2 degree FOV for larger DSOs.
I want to be able to repurpose my current alt/az mount, so am looking for just an OTA. I am not interested in serious astrophotography, but would like to continue my short-exposure EAA with my ZWO ASI224MC camera and Sharpcap, and also like to take afocal photos with my cell phone though the eyepiece. All my eyepieces are 1.25 inch and I don’t plan to upgrade them.
I have been reading about refractors and it seems that maybe a refractor in the f/5 range might fit the bill. From what I have read the more expensive ones minimize chromatic aberration, but I don’t know much this might be an issue for my purposes.

So, my requirements:
• Compatible with my current mount, Celestron says the weight limit is 12 lbs.
• Be able to mount a dovetail on the side on the OTA so that it will orient properly in the mount fork arm and not be so long that it hits the mount and limits elevation too much (although I have no need normally above 70 degrees).
• Be able to use 1.25 inch eyepieces, handle my uncooled astrocamera.
• Give a FOV of 2 degrees or more with up to 32 mm. eyepieces.
• Chromatic aberration not terrible for my purposes
• Budget of $500

Thanks in advance for any useful info that the always helpful CN community can provide.

Astrotech 80 mm ED doublet.   ~400 bucks. 2.9 degrees FOV with a 32 mm plossl.   Add 50 bucks for an economy 1.25 0.5x focal reducer to use for EAA.  I think that would work very nicely for your applications.  That should work well for EAA and if you decide to get more into straight up imaging, it is a nice scope to grow with.     Check out an app called Astroaide that can tell you with the FOV of the scope and camera combination.   You can get faster Achromat scopes like the Orion/celestron 80 mm Short tube refractors, but there will be significant CA  in your images.   I would google images taken with them to see if you find them acceptable.  

 

Cheers!

 

JMD

 

JMD

Edited by Wildetelescope, 05 March 2021 - 10:38 AM.

[kklei940]

One scope to look at might be a used 80ED, such as a Skywatcher EvoStar or an Orion 80ed. They come up on the classifieds quite often in that $500 range and would be a good match for your set up. While the focal ration would be F/7.5 and not F/5, it could still give you well over a 2 degree FOV with a 32mm plossl, or even a 25mm 60 degree eyepiece.

 

For the focal ration of F/5 you might look at a new short tube refractor since CA doesn't seem to bother you. Something such as an Orion Short Tube up to 120mm might fit the bill.

[Daveatvt01]

If you are open to other types of scopes, a schmidt-newt might work for you. Celestron used to make a 5.5” Comet Catcher that is f/3.6 and has more than a 3 degree fov possible with 1.25” eyepieces. It would need rings. There are other variants out there too, Meade made a couple of 6” schmidt newts. They can be hard to find though...

[alphatripleplus]

I use an Astro-Tech AT72EDII for grab and go and for EAA. As an FPL-53 ED doublet, it probably has better colour correction than the AT80ED, but not quite as good as a triplet like the AT80EDT. It fits your size and budget criteria.

[Echolight]

1/2 degree don't sound right.

 

With you 6 inch SCT and a 32mm Plossl behind 0.63 reducer you should have a 1.69 degree true field of view.

[rexowner]

Astrotech 80 mm ED doublet.   ~400 bucks. 2.9 degrees FOV with a 32 mm plossl.   Add 50 bucks for an economy 1.25 0.5x focal reducer to use for EAA.  I think that would work very nicely for your applications.  That should work well for EAA and if you decide to get more into straight up imaging, it is a nice scope to grow with.     Check out an app called Astroaide that can tell you with the FOV of the scope and camera combination.   You can get faster Achromat scopes like the Orion/celestron 80 mm Short tube refractors, but there will be significant CA  in your images.   I would google images taken with them to see if you find them acceptable.  

 

Cheers!

 

JMD

 

JMD

Couldn't agree more.  Just got an AT 80ED from Astronomics and couldn't be happier.  Great quality for the price.

[teashea]

I agree that an 80mm refractor would be a good choice.  There are lots of them available.  Check out some review and see what is available.  That will be a key factor.  Most telescopes are unavailable.

[SeattleScott]

1/2 degree don't sound right.

With you 6 inch SCT and a 32mm Plossl behind 0.63 reducer you should have a 1.69 degree true field of view.
16B73676-9ED9-4F17-8149-6A9FF0EE6AED.png

I assumed he meant 1.5 degrees, a reasonable generally accepted maximum for a C6, and just forgot the “1”

Scott

[Echolight]

I assumed he meant 1.5 degrees, a reasonable generally accepted maximum for a C6, and just forgot the “1”

Scott

That makes perfect sense. I've been considering a C5 myself, in case I ever decide to live in a van some day 

 

Figure the C5 tfov could be stretched to a little over 2 degrees, could fit in a large camera bag, and be sturdy enough on a light alt/az or heavy photo mount. And not sure a Questar, even with it's equal focal length, could use the accessories to match the fov.

[Joey44]

Astrotech 80 mm ED doublet.   ~400 bucks. 2.9 degrees FOV with a 32 mm plossl.   Add 50 bucks for an economy 1.25 0.5x focal reducer to use for EAA.  I think that would work very nicely for your applications.

Thanks to all for these suggestions-It looks like most of these scopes are on back order but maybe supply will improve when I am ready to purchase this summer. In regards to the recommendation for adding the 0.5 focal reducer, am I to assume that this would be screwed into the back of the eyepiece or camera nosepiece? And since I have a small chip ASI 224MC camera that the vignetting would not be too bad?

[SeattleScott]

That makes perfect sense. I've been considering a C5 myself, in case I ever decide to live in a van some day

Figure the C5 tfov could be stretched to a little over 2 degrees, could fit in a large camera bag, and be sturdy enough on a light alt/az or heavy photo mount. And not sure a Questar, even with it's equal focal length, could use the accessories to match the fov.

The baffle becomes a limiting factor real fast. It sounds like a reducer doesn’t offer a ton of benefit with a C5. A reducer with 30mm Plossl vignettes too much for most folks. Maybe reducer and 25mm Plossl. Most just don’t bother with a reducer or 2” diagonal on a C5 because you just don’t get enough benefit to make it worthwhile.

[Echolight]

The baffle becomes a limiting factor real fast. It sounds like a reducer doesn’t offer a ton of benefit with a C5. A reducer with 30mm Plossl vignettes too much for most folks. Maybe reducer and 25mm Plossl. Most just don’t bother with a reducer or 2” diagonal on a C5 because you just don’t get enough benefit to make it worthwhile.

Oh, Ok. I was under the impression that both the C6 and the C5 had 27mm clear aperture through the baffle. And given the shorter 1250mm focal length of the C5 vs 1500mm for the C6, the C5 would offer the potential for a slightly wider fov.

 

For the OP, maybe something like the Skywatcher StarTravel 102 AZ3 might fit the bill. $305 with mount. Probably lots of CA on bright objects. But big fov and decent on widefield targets.

 

Here's the same scope as the AT80ED. Says estimated delivery March 16.

https://www.ebay.com...c-/313118027647
The SV48 also looks interesting with it's 2 inch 2-speed focuser.