Affiliation
None
Thu, 12/23/2021 - 06:48
I am considering the following the back illuminated K400 for exoplant work shown here (click the "Back Illuminated tab):
FLI Kepler Cooled CMOS Cameras (flicamera.com)
It is a CMOS camera. By default it comes with a "roling" shutter. But I have read somewhere that electronic/rolling shutters cannot take dark frames easily. I have the option to order the camera with a 45mm mechanical frame. What are AAVSO member's thoughts on this?
Hi Ed,
For AAVSOnet, we use a "blank or dark" filter in the filterwheel for those occasions when darks are taken. On some telescopes in your back yard (such as BSM_NH2 here in my yard), you can cover the end of the tube. The dark filter of course uses one of your filter slots, so that option depends on how many filters you have and the size of your wheel.
Using a mechanical shutter is ok as well, but adds cost and complexity. If you use the mechanical shutter for exposure control, then you also make short exposures much more difficult (shutter vignetting on short exposures, plus a minimum exposure length that is far longer than possible with the electronic shutter). Mechanical shutters also wear out eventually, especially if you work on bright stars and take many short exposures to avoid saturation and then stack them later.
So there are many solutions for dark frames. Mechanical shutters are not bad, but I don't miss them.
Arne