K10D Stop down metering exposure problem

Will.

If you don´t want to hook your old manual 50mm to your K10D (which I don´t see the reason for not doing) you´re quite able to check this out with your AF 50mm if it has an aperture ring, as this is a problem with the camera and not specifically for old lenses.

My brand new FA 35/2 gets the same metering error results if using the aperture ring in manual mode, but works fine in the A-settings.

// Mats

No worries - actually, this granny's memory isn't as good as it was!!

I re-ran the tests using the plastic cover, and the measured exposure values were the same through the viewfinder and on the top LCD......(unsurprisingly!) I am surprised that it made such a big difference (up to 2 stops) - I have never found my film cameras this sensitive before.

I also ran extensive tests over the w/end with various manual lenses and subjects to get some idea of the scope of the exposure problem. In all cases, the results were the same: Exposure OK when aperture fully open, but starts to overexpose at about f8 getting progressively worse...the problem seems to be worse in low light.

There is a tendancy to underexpose sometimes when fully stopped down, but this does not appear to be evident when the viewfinder is completely covered. I supect that this could be an issue on a bright day or in low light conditions if you do not get your eye close enough to the viewfinder (eg: if' like me you are wearing spectacles) and thus the ratio of light entering via the viewfinder vs light entering via the lens is sufficiently skewed to cause the problem. (Not noticable unless stopped down metering is used - which is always is for manual lenses)

Anyway - I have now returned the camera for exchange together with all my test results and CDR of images clearly documenting the problem. (something for Pentax engineers to think about!) It will be interesting to see if the replacement body exhibits the same tendancies...will keep you posted!

We all know of the problems with stop down metering with the K10D, It doesn't work. The only way to deal with a quirk of a camera is to find another way of accurately metering. Start with what we know, most lenses appear to meter properly fully open, so if you want to meter for example f8 with a SMC M 1:2.8mm, open the aperture fully(f2., hit the green button to meter, shut down to f8(5 half stops/clicks) and with the EV steps set to 1/2 EV in the menu, increase the shutter speed by 5 clicks. f11 would be 7 clicks etc. Bob's yer proverbial.