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Message: <blockquote data-quote="Steve C" data-source="post: 1290902" data-attributes="member: 56622">Kevin,Thanks for those links.  I'll read them tonight.Now, I do know that FOV is real, measurable and comparable.  I evidently gave another impression.  So many degrees FOV= so many feet FOV.  That's pretty basic and I do get that (degrees field x 52.5= FOV).  I also place a lot more faith in FOV rather than AFOV.  AFOV seems to me to be a magnification favored specification (degrees of field x magnification = AFOV).  It's easier to increase AFOV with magnification than degrees of view.  Want more AFOV, get more magnification.  Want higher twilight factor, get more magnification.  Both are mathematical calculations based on magnification.   I'd bet that may be part of the reason that 10x is the most popular magnification.  Six degrees field @ 10x (Nikon Monarch) gives about the the same AFOV as 8.6 degrees field at 7x (Zeiss FL), with the latter having some 130' more FOV.  I know which one would give me the feeling of looking at more territory and which one I could find more warblers in a tree with, which one would give me the most relaxed image, and it isn't the 10x.  It's been a long day, and I have a headache.  Probably should have waited to post that.</blockquote>