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Hi Ray,
Always good to have another tool in the arsenal.
I am not sure that this is greatly simpler than some of the calculators around.
I spent a few minutes one day just taking the calculations out of John Smiths (CCDWare) calculator and assumptions based on some of Stan Moores work and his recommendations so I can use that in the field.
I just grab a couple of superfluous junk images while I am setting up taking a few focus tpoint mapping and images - since half the time I have no internet out there anyway - I needed a PC based calculator.
I take one of the rubbish images or a test image, whack the exposure time and the average background ADU into my little spreadsheet and it gives me the ideal minimum sub exposure time for reducing my read noise to within a fraction of the sky noise - usually about 5%
Noting that I had previously entered the other values for my cameras into a table - camera gain (available from metadata in the FITS header), pedestal, read noise and preferred % of read noise to sky flux noise (background).
The philosophy of this method is - the Noise I have control over is lost within the noise I have no control over !
But its certainly not a perfect tool for determining ideal exposure times for a given subject
It only gives me a recommended 'minimum sub exposure time' to reduce the effects of read noise, if I really want to capture deep fine detail then I need to go much, much longer and if I want to capture a high dynamic range then I will need some much shorter exposures as well so I dont have overexposed data.
So the imaging needs to be broken up into a series of exposure blocks for faint data, normal data and bright data
Maxim and CCDSoft have a pedestal value of 100 that they add to the signal so we need to remove this artificial 100 from the average background signal (its there to avoid the possibility of negative values in the calculations in final signal values)
Since 100 out 1000 is 10% its not insignificant
So just wondering if that is relevant to your calculation ?
Cheers
Rally
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