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04-14-2008, 03:50 PM   #1
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Green button and old lens

Hello,

I am a beginner and i have picked up a SMC-M 50mm f1.7 about three weeks ago. I love this lens and i haven't touched my only other lens (the kit lens) since.

I have a GX-10 and it has, as far as i can tell, the same exposure issues as the K10D. Using the green button, it underexposes from wide open until about f4, it's ok until f5.6, and it overexposes from there on.

That is true in normal lighting situations, but for some reason, when it get dark, it underexposes at all aperture. Actually, i feel like it is not possible to get anything above 1''6.

This is a big problem for night photography since i need to pretty much guess. I am getting quite efficient at this little game, but is there something easy i can do about that?

04-14-2008, 10:28 PM   #2
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QuoteOriginally posted by deudeu Quote
Hello,

I am a beginner and i have picked up a SMC-M 50mm f1.7 about three weeks ago. I love this lens and i haven't touched my only other lens (the kit lens) since.

I have a GX-10 and it has, as far as i can tell, the same exposure issues as the K10D. Using the green button, it underexposes from wide open until about f4, it's ok until f5.6, and it overexposes from there on.

That is true in normal lighting situations, but for some reason, when it get dark, it underexposes at all aperture. Actually, i feel like it is not possible to get anything above 1''6.

This is a big problem for night photography since i need to pretty much guess. I am getting quite efficient at this little game, but is there something easy i can do about that?
Try using the depth of field stop down feature on the power switch and using the +/- scale to set the exposure. I had to test my M 400/5.6 and find that if I metered at f/8, it gave me the base exposure correctly. Also, if for night exposure, you are away from the eyepiece, then the light coming in through the eye piece can throw the exposure off. Hold your thumb over the eyepiece while you push the green button and see if that helps - assuming that you do not have your eye to the eye piece for these exposures.
04-15-2008, 12:44 AM   #3
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Well documented problem with the K10. Fit a new focus screen .. an L80 or one from a Pentax DS. Cures the problem.
04-15-2008, 09:43 AM   #4
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QuoteOriginally posted by Canada_Rockies Quote
Try using the depth of field stop down feature on the power switch and using the +/- scale to set the exposure. I had to test my M 400/5.6 and find that if I metered at f/8, it gave me the base exposure correctly. Also, if for night exposure, you are away from the eyepiece, then the light coming in through the eye piece can throw the exposure off. Hold your thumb over the eyepiece while you push the green button and see if that helps - assuming that you do not have your eye to the eye piece for these exposures.
I will try it out, though i have a hard time understanding how the light going through the viewfinder would mess up the exposure at night.
I have been working with stop down feature as well. I like it almost better than the green button. It is just a little tough when using spot metering.

I know the exposure problem is well documented. I just haven't found anything about constant underxposure at night.

I was out yesterday night taking pictures again and the green button underexposes At all apertures, all the time.

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