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Optics Light Gathering Question

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/27/2010 at 00:06
Brazos_Jack View Drop Down
Optics GrassHopper
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OK, objective diameter divided by magnification equals exit pupil. Increasing optics exit pupil increases low light capability up to the point where it equals or exceeds that of the user – 7mm for young, healthy eyes, somewhat less at my age. However, evidently better lense and lense coating technology gives better low light capability in optics with equal exit pupil size. Hence I’m told Zeiss or Swarovski trumps Leupold with equal exit pupils.

My question – will an exit pupil greater than 7mm help overcome lesser lense coating technology – i.e. would a 6x56 Leupold give low light capability similar to a 6x42 Zeiss?

Brazos_Jack

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/27/2010 at 00:39
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Scopes transmit light rather than gather it.  Exit pupil is exit pupil once you get to the size that your eye pupil is anything larger is not useable so at that point larger has no effect.  The difference between good better and best glass will be noticable but the truth is that we are not trying to take a photo we are trying to get on target so while your view may look sharp and clear with the best glass in the world you might be just as effective at striking the target with average glass and what is often overlooked but most important is how well the scope holds its zero and how reliable and predictable the adjustments are.  Usually as you get into better glass the scopes are more expensive and the mechanical parts are better quality but even some of the moderately priced  scopes like weavers are legendary for holding zero really well.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/27/2010 at 07:31
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Optics GrassHopper
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Thanks Urimaginaryfrnd,
 
That's the information I needed.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/27/2010 at 09:14
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You are dealing with two systems, one linear, the mechanical scope, and one non-linear, the human visual system. Lateral inhibition may cause some part of the image picture to stand out whereas you may be more concerned with some of the backround. This is independent of the scopes physical qualities. Zeiss and Swaro optimize their lens for transmission in lower light conditions using modular transfer functions. MTF are used extensivley in camera lense evaluation, but as pointed out above the mechanics are more important. New develops in digital sensors will change alot of that by allowing control of the image picture in real time. If and when this is put in scopes is another question.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/27/2010 at 13:34
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+1 on the mechanics first, especially if you're dialing in longer range shots. But even when zeroing at 100 yards, I prefer a scope without any lash in the turrets. Some other things about the optical aspects though: A larger objective of the same quality will offer more light transmission, better resolution and sometimes with the larger exit pupil will make it easier to get a good sight picture. However, take stock of your overall requirements. For example, wanting a scope that would work from ranges between 25-600 yards, that was reliable with rock-solid target turrets, a ranging reticle, and relatively good glass led me to a NF 2.5-10X32 last year. I'd stack that scope up against many others with larger objectives and magnification ranges just because it packs so much usefulness into a relatively small package. But if I never shot over 300 yards, I'd be just as happy with a Leupold FX-II 4X, except for initially zeroing it in, which always exhibits lash.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/27/2010 at 13:39
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2 words: Bertrillium-Zantitium

"Light gathering" will NEVER be the same!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/27/2010 at 15:20
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Originally posted by Rancid Coolaid Rancid Coolaid wrote:

2 words: Bertrillium-Zantitium

"Light gathering" will NEVER be the same!
Roll on Floor Laughing
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