I've seen some of the controversy over Tony Northrup's videos, so I had to go watch them for myself. I understood what he was saying but I was still confused over possible differences between a m43 lens and a full frame lens. Rather than argue about it, I went and took some photographs to compare them. Using an f1.4/50 Takumar and my Panasonic 14-140 lens at 50mm, I shot two photos. Both are shot at f5.6, 1/25 of a second at ISO 160. In both images I manually focused on the 4x4 post in the middle of the frame. Guess what? The two images are essentially the same: same exposure, same depth of field. There are coloration differences, which is to be expected. The images can be downloaded from http://1drv.ms/1jXsdxT if you want to examine them. The upshot of this is that f-x is f-x. A given depth of field for a certain lens at a certain aperture opening is always the same. It is only when you start to compare the formats with comments like x-lens equals y-lens in some different format that things get complicated. This also means that if you have an old prime from a 35mm camera, the DOF guide is still going to be accurate when used on a m43 camera.