Quote:
Originally Posted by Amaranthus
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Yes, you have. Basically you have ignored how the aperture influences the "richness" of the field.
Many years ago there was an analysis which showed that a 6" (150mm aperture) f/5 scope is optimal in terms of its ability to pack the maximum number of stars into a given field of view - for a visual observer.
I won't go into the details here - too complicated - but I'll try to find a link for you explaining why this is the case. It is related to:
- the frequency distribution (by magnitude across the sky of stars and nebulae;
- the number of stars that can be seen as a function of aperture - this is not linear BTW;
- the sensitivity of the eye,
- the optical tradeoffs that occur regarding the actual field of view vs magnification and exit pupil.