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Originally Posted by Jasp05
Thanks again Rick,
Where do you get the "Signal" Value from?
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The rate at which signal is captured is proportional to the square of the aperture, the square of the pixel size (both measures of area) times an efficiency factor and inversely proportional to the square of the focal length. The efficiency factor takes into account central obstruction (if any), optical efficiency (100% less losses from from refraction and reflection) and QE.
I'm not trying to calculate in specific units. It's just a relative measure for comparison purposes.
Quote:
Originally Posted by Jasp05
Why does SNR = Square root of signal?
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The major source of noise should be shot noise (assuming your subs are long enough to be sky limited) and the amount of shot noise is the square root of the signal, hence signal/noise is also the square root of the signal.
Quote:
Originally Posted by Jasp05
Why does Time = 1/ signal?
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Time is again a relative measure representing how long it takes to accumulate signal. If you're collecting 10 e-/second then the inverse is 1/10 sec/e-.