Originally posted by atlnq9 Easier said than done. The 31mm is a 1.8 and the 28mm is a 2.8. So it is not a direct comparison even still. Never the less, the image would represent exactly what the meter thought. Thats why is you read up higher we were talking about metering through whatever the selected aperture was. Any picture with the Zeiss is metered at the chosen aperture while the Pentax is metered at 1.8 then calculated to the chosen aperture.
... and that is exactly what was going on, in particular with the Av mode. In full manual, each of the lenses had the manual aperture rings set to f4, but the camera body still knew that the 31 was a f1.8 lens. On the CZ 28 being a f2.8 lens (and no reporting capability), the body assumed a constant f2.4 for the lens (apparently a default for all pure K mount lenses).
The images were always wonderful - never a complaint (other than my poor manual focusing ability - but that another story). The main reason for this thread was I happen to see the wide differences in shutter times, and essentially wondered why....
Inquiring minds - and the like...