Originally posted by womble "Green button" stop down metering on the three dSLRs I have owned (K10D, K20D and K-3) has never been any more than vaguely in the ballpark with K and M series lenses, often being anything up to 3 or 4 stops out. I usually get closer guessimating and then adjusting using the histogram.
With the K10D it was indeed a bit of a hit and miss, but with newer cameras it's vastly improved and usually well into the ballpark. Even the K20D/K200D were an improvement already. With my K-S1 and now the K-3, the metering is reliable at least 90% of the time, and when it's off, it's never 3 or 4 stops out. More like 1 stop usually, rarely 2 (which happens usually when there's something white in one part of the frame so I know now just to deal with it beforehand).