Originally posted by Adam The 645Z supports open aperture metering, so it's normal for the aperture to stay open as you turn the aperture ring.
It's also normal for viewfinder metering to be slightly inaccurate with legacy lenses (this applies to k mount DSLRs too). Since it sounds like a -1EV compensation is what's needed with that particular lens, I'd recommend either using that or switching to live view, which will always meter consistently regardless of the lens type.
Finally, I doubt that the metering will be any more accurate in manual diaphragm mode, but if your lens supports it I guess it wouldn't hurt to try.
The 645Z does not control the 67 lens aperture thru the adapter, the aperture on the lens is closed as controlled, I watch in slow speed shooting ( over seconds) and the iris did not wide open at any time. The strange thing is that in LV, the metering is correct and speed are correctly changed according to the step down of the lens aperture, however, at actual shooting the metering is over, and the way its over is according to the step-down, i.e. step down more, than over expose more. I further tested the speed ( using tripod and facing same objects) and found following data on the 105 f2.4 lens:
At f4 speed is 1/250
f5.6 1/80 ( correct sped should be 1/125)
f8 1/20 (correct speed should be 1/60)
So obviously, the metering on the 645Z is getting less light than the CMOS when using the Pentax 67 lens with PT67-645 adapter while step down the aperture, therefore, the speed is incorrect when step down the aperture. While LV on the 645Z is not the actual view, so will not notice the exposure has been over. Anybody have any idea why?
---------- Post added 01-01-15 at 10:42 AM ----------
Originally posted by thomaskplee The 645Z does not control the 67 lens aperture thru the adapter, the aperture on the lens is closed as controlled, I watch in slow speed shooting ( over seconds) and the iris did not wide open at any time. The strange thing is that in LV, the metering is correct and speed are correctly changed according to the step down of the lens aperture, however, at actual shooting the metering is over, and the way its over is according to the step-down, i.e. step down more, than over expose more. I further tested the speed ( using tripod and facing same objects) and found following data on the 105 f2.4 lens:
At f4 speed is 1/250
f5.6 1/80 ( correct sped should be 1/125)
f8 1/20 (correct speed should be 1/60)
So obviously, the metering on the 645Z is getting less light than the CMOS when using the Pentax 67 lens with PT67-645 adapter while step down the aperture, therefore, the speed is incorrect when step down the aperture. While LV on the 645Z is not the actual view, so will not notice the exposure has been over. Anybody have any idea why?
Above have some statements confusing, the exposure in LV on 645Z is also not correct, just user will not notice it, as it automatically make adjustment on the display.