Jonas B wrote:
Increases or decreases the radial sharpness? Hmm. There is something here I don't understand: As point light sources, in focus, get smeared in a tangential direction (mostly) and can get the shape of gull wings it seems to me as sharpness, tangentially, is decreased. Then, why would radial sharpness increase? Isn't it either nearly unaffected or decreased as well?
Well, due to the effective aperture being smaller in the radial direction in the corners, the sharpness increases (it's like stopping down radially, but not tangentially). But sharpness also decreases because of other aberrations, and it could as well end up being equal or (probably) less good than the midframe sharpness anyway.
The most apparent effect of mechanical vignetting is that DOF increases towards the corners of the frame. This is very common with fast lenses, and it often gets worse the wider the lens is.
Makten wrote:
Well, due to the effective aperture being smaller in the radial direction in the corners, the sharpness increases (it's like stopping down radially, but not tangentially).(...)
Thank you Makten for straighten things out.
ovredal73: I'm sorry for my first confused post on the matter. Reading it again now make me blsuh. I mean, I know what the Kat's eye effect is and I know what coma is. Lol, I'll just not post about theoretic stuff when I'm tired... My normal confused me is bad enough.
Panasonic G1, Olympus Zuiko OM50/2 Macro with a Vivitar 2x macro Focusing Tele Converter between the lens and the camera. The depicted piece of the unknown pot flower seen above is about 11-12mm so magnification was up to a bit more than 1:1. With the aperture ring set to f/2.8 this was effectively 100mm and f/5.6 and quite close.
