I'm steeling my nerves to drop a bunch of cash and purchase a C11. I'll primarily be using it for planetary imaging and visual work, so I think I'll go with the XLT ... figure I can buy a bunch of neat accessories for the extra money an Edge would cost.
What accessories would you all recommend prioritising?
I currently have a 6SE with the following accessories:
- CEM60 mount
- ZWO ADC
- Baader Clicklock SCT adapter (with 1.25" converter)
- Baader Zeiss Prism Diagonal
- PowerMate 2.5 and 5.0
- Celestron 0.63 reducer/corrector
- Various eyepieces
- ASI290MC planetary camera, ASI174MM Mini guide cam
- Celestron OAG
- Various adapters and extension tubes
And probably some others that I'm forgetting.
Will my Baader Clicklock adapter fit on the C11 XLT?
Is there any point converting my Baader diagonal to 2" fittings and using 2" eyepieces?
Thanks in advance!
>>Will my Baader Clicklock adapter fit on the C11 XLT?
Yep. C11s actually have two sets of threads: standard 2" SCT threads, and a larger, 3.25" set of threads that can be accessed by removing the 3.25" to 2" adapter on the back of the scope. So yes, you could use the Baader Clicklock visual back with the 2" threads.
However, the rear baffle tube of a c11 is 54mm wide. Using the 2" adapter and a 2" SCT visual back (or 2" SCT diagonal) fails to take maximum advantage of this when using the widest 2" eyepieces, adding a bit of vignetting. For this reason, Baader makes a Clicklock visual back that threads directly on the the 3.25" threads:
This larger adapter with a 2" diagonal would be the best way to go if you want a Clicklock solution, as it will will help to minimize vignetting with the widest TFOV 2" eyepieces.
>>Is there any point converting my Baader diagonal to 2" fittings and using 2" eyepieces?
The Baader T2 diagonal only has a 34mm clear path. Baader does not recommended it for 2" eyepieces, as it will cause vignetting.
The F/6.3 R/C has a clear aperture of 41mm, so, again, it will add a bit of vignetting when used on a C11 compared to using the larger visual back and a 2" diagonal.
All that said, the vignetting caused by limiting the light path from 46mm to 41-42mm (using the R/C or a 2" SCT visual back or diagonal) is not going to be readily apparent to a visual observer. I'd avoid choking it down to 34mm, though.
Most C11 users use 2" dielectric diagonals, as 2" prism diagonals are rather expensive. Your prism should still be a better pick for planetary viewing or splitting doubles at the highest magnifications, though. To max out the TFOV on a non-EdgeHD SCT with a 2" diagonal, a 38mm SWA/Q70 is a nice affordable alternative to a 41mm Panoptic or 40mm ES68. Or a 55-56mm Plossl, if you also want to maximize exit pupil.