Multisegment metering has no clue as to the color/shade/tone of the paper.
Multisegment will never make it white without user intervention. As to the exposure an eyedropper on the image will show RGB at approx. 90/90/90 though there appears a slight amount of toning. I'd check for you but oddly enough I have no photo software w/ me at the moment.
to quote a source I believe:
18% grey appears as 110/110/110 in RGB color space , gamma 2.2.............\
In the middle of the histogram you can assume linearity. not so for the ends.
So roughly 40 "points" in RGB would be a full stop.
assuming 110/110/110/ is the EV value that the meter is trying use 70/70/70 would be a stop down from there. Of course 150/150/150 is a stop up.
Many camras use 110, Pentax has (for whatever reason) been known (or assumed) to use 90.
Personal proof is w/ MY *ist-D it would do a "white wall" at 90. After a few years I sent it to Pentax for some "issues". Supposidly they recalibrated the camera and it came back an "88".
To me this just shows you that 90 is "their value". Both Nikon and Pentax seemed to drift (within 1/2 stop) this figure between camera models. Only thing that surprises me about your camera/photos is that they seemed to go back to the 90 calibration..... though maybe just a bad hair day at the calibration factory for you.
Second example is if you shot the grey card w/ a Caon camera you would find that the peak is
at 127/127/127......... not because of a better meter, just because they cheated on the iso.
I recommend everyone to read Mr. Kerr's papers:
Articles by Doug Kerr http://doug.kerr.home.att.net/pumpkin/Exposure_Calibration.pdf
Oh and to add my favorite quote form my favorite Leica icon:
'The exposure meter is calibrated to some clearly defined standards and the user needs to adjust his working method and his subject matter to these values. It does not help to suppose all kinds of assumptions that do not exist.'
Erwin Puts
Last edited by jeffkrol; 06-02-2008 at 11:54 AM.