After seeing threads about inaccurate exposure with non-A lenses, I hauled out my tripod, my K10D and my SMC-P M 100/4 Macro, and did some testing.
I found that in Av mode the exposure was virtually unpredictable, but I need to do some retesting to find out if it is a "one stop" mode. In M mode, I found that I could get consistent results only at f/5.6 through f/11, and to get an accurate reading on the exposure scale, I needed to stop down with the dof preview once, and then again. So my procedure is going to be
- Set the f/stop
- Move the exposure switch to dof preview
- release
- dof Preview again and hold while adjusting exposure
It looks like my macro is "f eight and be there" +/- one stop. On either side of that, it underexposes. 1 stop or thereabouts at f/4, and at f/22 my dark side blinkies outshine Darth Vaders light saber. I noted that the shutter speed recommendations did not change as I went from f/stop to f/stop outside the f/5.6, 8, 11 range.
The next tests will be to do the same with my M 400/5.6.
I would be interested in seeing how others have made out with various K and M lenses.