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Message: <blockquote data-quote="Swedpat" data-source="post: 3149793" data-attributes="member: 21414">A few years ago I thought about this. Actually I wondered if a wider FOV should not decrease the brightness.The basis for this idéa: with a certain aperture and magnification a wider FOV results in more light can reach the eyes when looking on a light source or light sources.For example: more stars in the FOV means more visible light sources=less light per area because the aperture limits the collected light. And if looking at the moon at 140x: with 50 deg AFOV half the moon area will fit in the field. But at 70 deg AFOV the entire moon will fit. With a certain amount of light collected by the objective lens the relative brightness should be half with the 70deg eyepiece, logically...But the explanation by David in #13 is the first explanation I have read in this matter! :t:</blockquote>