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Old 12th March 2013, 11:01 AM
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RobF RobF is offline
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Only because the aperture of the camera is changed to allow exposure to be correct.

The only thing that changes in the shooter's equation is the eye's iris. But the exit pupil is always smaller on a high mag scope than the eye can close down to.

What probably happens is that the better light allows people to determine focus more accurately in brighter conditions than in dark ones when only a more severe loss of focus registers as an incorrect range. The eye determines focus by contrast. In darker conditions there is less contrast and thus it's harder to determine the correct range. For more vague scopes, unable to determine extremely detailed differences large enough for the eye to see, there will be a range where no change in apparent focus is seen, perhaps 2-3 yds, so the eye picks up the change at the edge of this range, where there is a definite one. In better light this range of 2-3 maybe 1-2 yds on a good scope. This is why it's important to focus on detail which reveals a change in focus, and not something ambiguous like a plate. I work on string frays and such. The march can see spider web strands, count the threads on a bolt, or the teeth on a cable tie, or even a flys' leg, at 55yds. If you cant see these details, and use something like the string as a whole, then you get a wider range of error. In bad light, an even wider range. That's why I think light conditions play a part. In hazy bright overcast days, where there's a loss of contrast, the problem becomes the same, the eye is overloaded. Again, important to find detail that isn't so affected.
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