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Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
40 v 50 v 56 mm Objective Lens
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<blockquote data-quote="ricka0" data-source="post: 76755" data-attributes="member: 3086"><p>I went to the eye doc today and had him measure my max pupil - it came out 7mm. (probably was 8mm 20 years ago /ubbthreads/images/graemlins/frown.gif )</p><p></p><p>Using the simple Formula <strong>Obj/Power = exit diameter (ED)</strong> I calculated the max power I could put my favorite scopes under low light conditions and not suffer blackout.</p><p></p><p>Plugging in my 7mm: <strong>Obj/ED = Power</strong> <ul type="square"> [*]56/7 = 8 Power [*]50/7 = 7 Power [*]40/7 = 5.7 Power [/list] </p><p>Now you can't judge a scope simply by Objective Lens, but you can probably compare a Loopie VX-III 40 v. 50, or a NF 50 v. 56</p><p>A fun thing to do is put point your scope near a light (arms length away), and turn the power up and down and see the exit pupil dilate/contract.</p><p>Is it worth the extra money going from 40 to 50 mm on a loopie or 50 to 56 on a NF? In the case of NF I doubt it as most scopes the question is 40 v 50.</p><p>The total light gathered is limited by the Obj lens is simply pi*(Obj/2)^2 - so light input goes up as the square of Obj lens - <strong> <font color="purple">BUT </font> </strong> additional height is simply Obj/2 - so going from 50 to 56mm only requires 3mm more height.</p></blockquote><p></p>
[QUOTE="ricka0, post: 76755, member: 3086"] I went to the eye doc today and had him measure my max pupil - it came out 7mm. (probably was 8mm 20 years ago [img]/ubbthreads/images/graemlins/frown.gif[/img] ) Using the simple Formula [b]Obj/Power = exit diameter (ED)[/b] I calculated the max power I could put my favorite scopes under low light conditions and not suffer blackout. Plugging in my 7mm: [b]Obj/ED = Power[/b] <ul type="square"> [*]56/7 = 8 Power [*]50/7 = 7 Power [*]40/7 = 5.7 Power [/list] Now you can't judge a scope simply by Objective Lens, but you can probably compare a Loopie VX-III 40 v. 50, or a NF 50 v. 56 A fun thing to do is put point your scope near a light (arms length away), and turn the power up and down and see the exit pupil dilate/contract. Is it worth the extra money going from 40 to 50 mm on a loopie or 50 to 56 on a NF? In the case of NF I doubt it as most scopes the question is 40 v 50. The total light gathered is limited by the Obj lens is simply pi*(Obj/2)^2 - so light input goes up as the square of Obj lens - [b] <font color="purple">BUT </font> [/b] additional height is simply Obj/2 - so going from 50 to 56mm only requires 3mm more height. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
40 v 50 v 56 mm Objective Lens
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