Quote:
Originally Posted by gregbradley
What is the conclusion you would reach from this model about pixel size and sensitivity?
You mentioned it was a very important factor as its one of the terms that is squared.
One bit of empirical observation was on my CDK17 one time I imaged M104 with both Proline 16803 and then Microline 8300.
Same night, same scope, same conditions. I was surprised to see the 8300 lacked resolution and was dimmer but what surprised me most was it was blurrier. Seeing hadn't changed as far as I know.
Greg.
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assuming you were imaging without an FR, the figures for your 2 configurations are:
S(16803) = 0.53*0.75*9*9/6.3/6.3 =0.81
S(8300) = 0.47*0.75*5.4*5.4/6.3/6.3 =0.22
ie, the sensitivity of the 8300 system was about 1/4 that of the 16803, so it would have had much worse noise. the 8300 has about 2.5x? the gain of the 16803, so the the ADU brightness on the screen would have been about 2/3 that from the 16803.
The 8300 system was heavily oversampled, resulting in poor SNR and excessive image scale, leading to a perception of a lack of sharpness - it would have looked c**p.
By itself, pixel size is unimportant - however, it is vitally important in a system context and must be considered along with Fnumber, focal length, efficiency etc, when working out what a system will do. the equation encapsulates how pixel size interacts with other parameters in determining sensitivity but, as Colin pointed out, you must also consider other aspects such as resolution, field of view etc.