## Re: Light collecting power and aperture.

Well we could have done the whole thing for a 5 mm eye pupil and picked magnifications such that the exit pupil is smaller. For simplicity let's just assume 5 mm.

Let's say we have 10x50 binos and we have telescopes with a 30 mm eyepiece and an F ratio such that the exit pupil D/M=5 or D*30/F=5, or F ratio F/D=6. Then in all cases we have a 5 mm exit pupil.

Stars are viewed as parallel light bundles so the intensity is proportional to the square of the aperture D.

For surface objects the flux is determined by the F ratio like in AP. So for the case of a constant F ratio of 6 the flux does not change in function of aperture. This is very different from viewing stars. The brightness would be the same for all cases. Your table does not apply to DSOs, only stars.

PS (edit): I noticed my reply crossed with yours, thanks for your update, I will check the references.

... Henk.

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