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07-30-2012, 11:40 AM   #1
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What lighting conditions do you do to calibrate your lenses?

I tried calibrating in dim light with ISO 1600 at f2.8 before trying it in a decent light with ISO 80 at 1/30s and f2.8. I find it that in low-lighting at 1600iso settings, it tends to focus spot-on or not spot-on; like when I set it to -5, sometimes it's just as in focus as +5. All this time I thought my 50-135 f2.8 had severe backfocus so I set it to +10 just before I did the testing today again. When I tested it out in decent light at ISO 80 and f2.8, I find that it focuses consistantly and my lens is set perfect to +2. How do you shoot at dim light at higher ISO's with it being spot-on focus all the time?


Last edited by LeDave; 07-30-2012 at 12:00 PM.
07-30-2012, 11:52 AM   #2
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Are you talking about the k-5? Or the k-30?

Light affecting the focus is lens independent, I believe...
07-30-2012, 11:58 AM   #3
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Original Poster
QuoteOriginally posted by JinDesu Quote
Are you talking about the k-5? Or the k-30?

Light affecting the focus is lens independent, I believe...
I'm shooting the K-5, at high 1600iso settings, it's not shooting at flourescent lighting (Which I believe some K-5's have focus issues with, mine don't), just natural light but very dim as it's inside the house with light leaking through the closed window blinds/ Again, at 1600iso/f2.8 and good enough shutterspeeds for the focal lengths of the 50-135 (looked at the photos, no motion blur).
07-30-2012, 12:04 PM   #4
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That I'm not sure then - I understand that the k-5 has front focus under tungsten lighting, but if it's natural daylight, I can't say.

I will say that my k-x doesn't have discrepancies based on the amount of light available when I did my focus test, but it did have some errors where the camera shot before the focus was actually perfect - showing me front focus. It was front focus because my method of testing was to rack the lens to minimum focus distance, then letting the AF hit the target.

If the focusing isn't consistent in the same set of tests, then something is wrong with the target or the method.

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