Originally posted by tr13 Interesting measuring, Lowell.
But I think that poll is much more useful, anyway.
except what is the poll going to ask, you are dealing with a characteristic that changes potentially with every lens at every aperture. about the best you could do is have a poll where you enter error for ewach f-stop. i am not sure it can be done
Quote: As for focusing screen non-linearity is could be possible in case of special materials with concentrating lenses (not just glass).
note the errors exist even if yoou take an A lens out of A and meter, and although there is a variation lens-to lens, most lenses have this characteristic
Quote: But I strongly belive in my previous points.
you are entitled to your opinion, but note. The brighter focusing screen of the K10/K20 may also have a property to scatter light differently, causing more than just the light that the metering should look at hitting the meter. This scatter may be a function of how parallel the light is hitting the focusing screen. the more you stop down a lens, the more parallel the light is hitting the focusing screen at each point, therefore the screen could cause the problem entirely by itself. If you want to confirm this
Quote: As for how we could make M lense to behave like A lens - it is quite easy. All that we need to change is lever moving distance. As M lenses have different distance to diaphragm relation.
not as easy as you think, you also need to know the maximum aperture of the lens mounted on the camera.
Quote: I'll try to make comparisons between M42, M and A lens in same situations. As M42 don't have any stop-down during measure and A don't have it either (only calculations are made).
I have the graph for all 19 of my lenses, both A and non A lenses, but have not checked 100% of the A lenses in Non A mode. I also have not checked these lenses on my K7 Yet, but plan to. Note each lens takes about 15-30 frames per camera body to test for each metering mode,