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Old 22-06-2015, 05:11 PM
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Atmos (Colin)
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Join Date: Aug 2011
Location: Melbourne
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The equation that I have been using for a while (takes 20 seconds on my phone) doesn't go into much depth with average sensitivity or even different telescope efficiencies BUT.

P= Pixel in micron
Fl= Focal Length
A= Aperture
QE= Quantum Efficiency

((((P*206.265)/Fl)^2)*A^2)*QE

What this calculation does is give a correlation between the amount of light entering the system (the aperture) compared to the amount of sky that each pixel covers. With a very slight modification to the above equation, adding:
TE= Telescope Efficiency

This gives the difference between different optical qualities and telescope designs if you so desire.

((((P*206.265)/Fl)^2)*(A*TE)^2)*QE

Quote:
To work through an example; say you want to compare:
a 300mm f3.8 Newtonian + 16803 camera (system 1)
with a 200mm f8 RC + 8300 camera (system 2).
S1= 126,487
S2= 9110

This is a difference of 13.89 times. Of course, this is the difference between S1 having a sample size of 1.63 arcsec/pixel and S2 having 0.696 arcsec/pixel. This is to be expected when you have a smaller telescope with smaller pixels imaging with a longer focal length.
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