|
Trying to achieve focus with QHY12 CCD @ prime focus
Hi all,
I recently acquired my first CCD and had some trouble getting it to focus for first light.
My image train was :
C9.25" SCT -> 6.3 Focal Reducer -> T-adapter -> QHY Clip -> QHY12 CCD
All I was seeing on Nebulosity's "Frame and Focus" was gain noise when I cranked the gain up. Verified it was working by shining light down the tube, that showed up ok. But twiddling the focus knob slowly from one way and then the other showed basically nothing, not even an airy disc. (Admittedly I was on Comet Lovejoy and not a bright star, but there were other stars about it).
Could it be that the focal reducer makes the focal point impossible to reach?
Are there any tips for getting near rough focus from complete darkness when going from the Star Diagonal to the CCD?
Sorry for the silly questions! When I use a DSLR with the same image train I can get focus .. I crank up the ISO in Backyard EOS, twiddle focus to see airy disks then move in from there. Typically about 20 small turns in one direction.
d
Last edited by dylan_odonnell; 08-01-2015 at 04:53 PM.
|