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01-06-2010, 09:47 PM   #16
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I finally figured it out. Lowell and the others that thought it might be the split screen. I believe that you are right. I hadn't seen this effect before because I don't use the kit zooms often and they are the only K mount lenses that I have with a slow max aperture (3.5)

Here is what I found out.

1. in spot mode the split prism caused the error in the metering because it is darker. I have not seen this with my other lenses that I use spot metering with because their max aperture is 2.8 or faster.

2. in center weighted it is better because it averages around the center, too, I assume.

3. in matrix mode, though, it was as bad as the spot meter. In fact, the exposures were identical. This really baffled me as I would of thought that the area to determine exposure would be greater than the center weighted and thus less dependent on the center. Ultimately, I expected an exposure at least similar to the center weighted. But I didn't. Instead I got the same exposure spot metering was getting. This is because:

In the custom menu, I had switched ON the feature that links AE with AF point. This is a feature on the K10d specific to Matrix mode. Wanna guess where I have had set the AF point? Right, in the Center. Thus this is 'like' the spot mode in that the Matrix exposure is relying on the area around to AF point (center) with the split prism and thus the like (incorrect overexposed) exposure.

To test this, I turned off the custom feature. The matrix mode worked fine, now resembling center weighted. Then I turned it back on and proceeded to move the AF point away from the center. As long as the AF point was anywhere other than the center, Matrix gave me an acceptable exposure reading.

Lastly, there was a thread many moons ago that discussed the merit of locking AE with the AF point. There seems IIRC that many felt it only worked with the center AF point. This little 'experiment' implies to me that in Matrix mode with this custom feature on, those that like to move the AF points can also have the Matrix exposure 'biased' in favor of the off center AF point too. I don't know if it is truly an off centered spot meter in this case. But, in my case, the center AF point gave the same, albeit, incorrect exposure as the spot meter mode, suggesting that it is not using much information outside of a small area around the AF point to calculate an exposure.

I hope this helps someone else too.

Thanks to everyone again!

01-07-2010, 11:54 AM   #17
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Forgot to say that I tried the kit 18-55 mm and I had the same results.

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