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Old July 26th, 2012, 12:21   #23
Dimitri
Can't do math
 
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Join Date: Oct 2009
Location: Toronto
Quote:
Originally Posted by highny View Post
Just to make sure you understand the numbers in describing scopes: example:
3-12X40mm.
3-12 is magnification
40mm is the size of the picture
No, it is a 3-12 magnification, but 40mm describes the objective lens.

The size of the picture is the field of view, which has little to do with the objective lens.

Both the field of view and eye relief depend heavily on the way the lenses are stacked internally inside of the scope. Which is dependant on many things, including the objective lens and the magnification (as they determine the interior layout of the lenses), but different 40mm lensed scopes will have different fields of view and eye relief, sometimes the differences are very drastic.

Dimitri
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