I am currently imaging with a RC 8“ and ASI 1600MM from a light polluted backyard (Bortle 5/6). For narrowband, total integration times to get acceptable results is great (1 object per night, 2 nights in summer). I would like to keep the image scale below about 0.8 arces/pixel to take advantage of the rather good seeing I often observe. At native image scale of 0,6“, I need long total integration times for broadband to ger decent SNR (20+ to 30+ hours, depending on object). I tried the CCDT reducer but it causes image tilt and/or reflection and is a hassle to set up properly in my setup. In-driver binning does not work well with the ASI1600, and I wasn‘t able to reproduce the theoretical SNR-increse by binning in software (workflow: Mure Denoise, Resample, Stretch). I have used an etendue calculator to show which scope/camera combination might improve on the imaging times. As a mount I have a Mesu 200 Mk2 coming in, so weight should not be much of an issue. I am aware traveling to a dark site would be better, but that is not an option (I am very frequently on-call as a physician). The following should, I think, provide substantial speed improvements:
+ Proven performers
CDK 12.5/Qhy600M or Asi6200MM
+ (Quite) a bit cheaper, but still pricey with new filters and FW
+ High QE
- Needs CMOS binning
ONTC Newton 10“ f/4/Qhy 690
+ Lowest price (can keep using current filters)
- Frequent difficult (?) collimation
- Rather small fov (but not by much)
ONTC Newton 12“ f/5/Qhy16200A
+ Largest Fov
+ integrated camera/fw
- Frequent collimation, but easier
EdgeHD 11/Qhy600M or ASI6200MM
+ Still in budget
+ Large user base
+ Highest etendue
+ Lightest scope
+ Also good for visual/planetary
- Needs CMOS binning
- Scope needs tweaking for auto focus (probably secondary mirror focusing)
Although the CDK looks very appealing, at the prices in Europe, money does play a role.
My questions would be the following:
- Am I right in assuming I could decrease total integration time per target by a factor of about 5-6 with the above combinations (or use the time to further increase SNR)?
- Have I overlooked any issues with the above combinations?
- Any bad/good experiences with any of the above with imaging smaller DSOs?