Yeah, it's like the numbers don't match how a real camera lens would work. The only thing I really remember from photography is that the longer the lens I would use the wider the DOF I could get. But then I'd have to be farther away from the subject to frame it right. With Poser you don't have to worry about that. Also because of that you can make the mistake of using a large focal with a small DOF and make everything in the image look like miniatures.

W10, Ryzen 5 1600x, 16Gb,RTX2060Super+GTX980, PP11, 11.3.740