Originally posted by audiobomber Wouldn't an APS-C camera require some adjustment to this rule of thumb? I thought that any given F-stop on a 35mm would be one stop faster than the equivalent aperture on APS-C. If that's true, then for a digital Pentax, Sunny 16 should be Sunny 11?
Not for exposure. The one stop comment is on the effective depth of field.
Early on with the K10, I did some experimentation with my M 400. The threads on using the manual exposure only lenses were not as clear as they are now; the K10 was the first model to show this metering difficulty. We discussed whether the different rate of movement of the aperture by the lever was the problem, or whether it was the metering that was off.
I tested using Sunny 16 and my M 400. The series is on my Flickr site, and proves to my satisfaction that it is the metering that is at fault. The series is identically exposed. Subsequent threads over time led me to replace the focusing screen with the one from the *ist series. This removed all the metering errors on my camera.