"Hi Joe,
Do you know how they arrived at the figures listed at that site? I'm of the opinion that we won't know what they are actually using until someone posts the DOF scale values off a late DA lens."
Rob, from a little browing that I have done, there seems to be a consensus that 0.030 is a reasonable CoC figure for 35mm. This yields 0.020 for APS/APS-sized sensors.
There is, as you know, no correct figure. It depends on how stringent you want to be. Warren Young, who wrote fCalc (right here in New Mexico!), used 0.033 for 35 mm. in an earlier version, but noted that Zeiss used 0.025. I note that in the current version of fCalc he adops 0.025 as the default for 35 mm., but allows one to change that. That would yield a CofC of 0.0167 for the *ist D.
I think the figure to use depends on how critical you are about what appears to be in focus at various display sizes. My feeling today is that 0.020 is a pretty reasonable mid-range figure.
Pentax Japan will probably never tell us what they use.
Joe
