Exposure Calculator

[Hy Murveit]

Joseph,

Thanks so much for getting the exposure calculator up and running in
KStars. Impressive accomplishment!

I just tried using it, and have some questions/comments I was hoping you
could address.

Here's a screenshot, with questions below:
[image: Screenshot 2023-05-17 at 10.13.06 PM.png]

   - I think I filled in the boxes appropriately above, though not sure,
   please let me know. I tried these values: sky quality 19 (about what I've
   measured at my house), f/8 reflector, full bandwidth (300nm), my ZWO
   ASI1600mm camera at gain 75 (I assume it wants the gain I use for the 1600,
   but I tried other values too), 20 total hours of exposure time desired,
   default noise increase of 5%. It seems to be telling me to take 5956 images
   each 12.09 seconds long, which is obviously not a good answer. Am I doing
   something wrong?
   - Not sure what Stack Time, Stack Noise, and Ratio mean. Are shot noise
   and total noise in electrons? (Need tooltips to help)
   - I was able to get it to give me a reasonable exposure time (e.g. about
   a 2-minutes) if I set Noise Increase % to 0.4, but I really didn't know
   what to put in there, and so used the default was 5%. Do you know, is 5% a
   good default for the noise increase? Can we give more guidance on what
   noise increase people should start with?
   - The tool needs better tooltips for pretty much each value that needs
   to be entered.  Most  tooltips say "An implementation of Dr Robin Glover's
   exposure calculation." We can give credit elsewhere (e.g. usually done in
   "About KStars"), but the tooltips should be informative. For instance, is
   gain the actual gain values one enters for the camera, or do you mean
   something like quantum efficiency? Assuming it's the value entered to the
   camera's driver, you should say that "Gain value used for your camera".
   Filter Bandwidth should include units (e.g. nm in this case.).
   - Don't need 3 decimal places for Sky Quality (make it one or two
   decimals). Ditto for focal ratio.
   - Is there some documentation on use somewhere? E.g. can a section be
   added to the handbook? Also, please start a forum thread describing this
   new tool and how you recommend users use it.

Thanks again,
Hy
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