|
So help me out here guys - place a parabolic dish - say a metre in diameter down a 40 metre tube, cover said dish in a CCD array, cool it to - 75 and do you have a quality 1 metre diameter telescope with beautiful readout (low Q/E) signature with an F ratio of effectively 0?
I can see how longer shots improve your signal, well up to the point your either saturate your wells in each pixel, and I can see how there is diminishing signal gain with time and I get you have readout noise and residual sky glow noise to contend with - and that this is why a series of shorter stacked shots - (so long as they can get sufficient signal) may be better in particular circumstances then longer duration single shots. But in essence is lower F ratio just better signal to noise due to less magnification?
How or rather why does lowering F-ratio work from a lay person's perspective please?
|