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12-16-2008, 03:11 PM   #16
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QuoteOriginally posted by jeremy_c Quote
The EXIF information should be intact, you can easily see it was indeed +1EV. I *have* to shoot +1EV on almost all shots w/the 18-55. It will be very dark with out it. This is not alledged, this is fact. I may not understand some other aspects before they were explained here, but I do know that *any* shot I take with the 18-55 is very dark. I always have to add +1EV to make it even close to normal. Indoors, outside, a book, a sky, anything I've ever shot with it needed +1EV. Others as well have said the 18-55 is dark, some have had to add +0.7EV. I don't think anyone said they need the +1EV that I do, but a few have the exact problem I do with the 18-55.

Jeremy
Is it consistent? Shoot a white wall or some such and change aperture values.
Lenses do have a chip and I suspect some feed certain parameters to the camera body. Maybe there is a "fudge factor" built into the lens to change the metering value. If your camera is slightly out of spec as to the meter baseline the fudge factor would shift it even more than intended. My guess of course. Check consistency using RAW and the histogram to rule out aperture problems. Send both to Pentax for calibration. A white wall should have a histogram peak at 110 in RGB space. This is slightly left of dead center. Pentax cameras can hit somewhere from the first quadrant line to 1/2 between second quadrant.
My k200 hits 110. My D hits 90..............

12-16-2008, 05:11 PM   #17
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QuoteOriginally posted by jeremy_c Quote
The EXIF information should be intact, you can easily see it was indeed +1EV.
Indeed, but I can also see from the EXIF that this was shot using spot metering. And perhaps the spot was on an area with light text. It's just too hard to tell from that one sample ifthere is 8actually* a problem here. All I can say is that at first glance, it's strange enough to be worth investigating further. But if you're going to do so - and I think you should - it's important to understand how to do so properly, so other variables (like spot metering here) don't throw off the results.

QuoteQuote:
I do know that *any* shot I take with the 18-55 is very dark.
It is indeed possible your lens or camera is defective. but if you're looking for validation of this claim, you really to post some well-controlled test results. Shoot at something *other* than maximum aperture so you're not simply seeing the effect of over-optimistic maximum aperture, use center-weighted metering or multi-segment metering on a subject that has a very clear range of "correct" values (eg, not one with bright highlights or high contrast or anything like that).

As it is, I simply don't see any reason not to assume user error. And I don't mean anything personal by this: I would say exactly the same to anyone who presented with the same evidence you have. It's just not very conclusive. Maybe there's a problem, maybe not - it's impossible to tell for sure based on what you've posted thus far.
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