Using Focal Reducers On Full-Frame Bodies

dan pv wrote:

I have tried some MF and LF lenses with my Leica R-Sony Nex Metabones SB. It doesn't matter that the lenses have a huge image circle - the SB will only cover APS-C.

False. Most designed-for-APS-C focal reducers will cover a 24mm square, and perhaps a bit more... which is useful.

However, coverage is very lens dependent. MF lenses tend to assume a wider obstruction-free path, so it wouldn't surprise me if they vignette MORE than most FF lenses when used on a focal reducer.

I am also interested in a 0.5 FF SB. I've seen some attempts to make a scan-back for LF cameras in order to revive the unic rendering of some LF lenses, but all were low resolution captures of the ground glass. A 0.5 FF SB would offer the full resolution of the 6x9 lenses with a gain of 2 F-stops while preserving their unique "character". I did some experiments with achromats placed at the back of the lens and it seems to work, but not without some flaws. I've used a Leica Elpro II achomat and, while preserving (or even increasing a bit) the central resolution of the lens it slightly softness the edges when the lens is used fully opened. Closing the lens down improves corners but you lose the "character". However, I think that this setup is usable for portraits, some closeups and soft focus images but not for landscapes or images where one needs very good corner sharpness at large apertures.

It's very hard to make a large-reduction focal reducer... until somebody figures-out a way that it isn't.