Last night a thought crossed my mind. Am I taking appropriate length sub exposures? I came across the Starizona Ideal Exposure calculator and decided to have a play around.
http://starizona.com/acb/ccd/calc_ideal.aspx
Now my QHY8L is not listed, but I assumed that I could use either the QHY8 or QHY8 Pro that is listed (both do give the same result).
Using a couple of recent images, I opened them up in Maxim and used the "minimum figure" as my background ADU (not sure if this is the correct method).
The images were captured with the same setup, just different locations.
The equipment is as follows,
Imaging scope : ED120 with WOIII 0.8x flattener/reducer = 720mm f6
Imaging camera : QHY8L
The subexposure details are as follows,
1. Metro Adelaide (Maxim information mode - area) 10minutes
2. Metro Adelaide (Maxim information mode - aperture) 10 minutes
3. Dark site (Clayton) (Maxim information mode - area) 20 minutes
4. Dark site (Clayton) (Maxim information mode - aperture) 20 minutes
When I input the data in to the "calculator", I get 2.34 minutes for metro and 4.09 minutes for dark sky site as the "ideal sub exposures".
Surely this cannot be right?
So in essence, how do you know when you are at a point in terms of exposure length, that you are at
the optimum exposure length?
I think the next time we have a bit of a break in the weather, I will run some trials at various exposures and try and determine the differences.
Look forward to some thoughts and experiences.
Cheers,
Daniel