|Posted: Wed Sep 13, 2017 12:09 pm Post subject: Kern&Schneider 25mm
|On MFT my Switar 25\1,5 and my Xenon 25\0,95 both start hard vignetting at about f4. The Switar fits its inside the "dip" necessary to get correct rear flange distance. The Xenon rear diameter is too large for that, but a slight adjustment of the helix mechanism corrects for that.
I would imagine that the later Kern optics marked Rx, hence corrected for the Bolex beamsplitter glass in the later H series viewfinder, would perhaps perform better with the MFT sensor glass.
The only 16mm Zooms I have, the Angenieux 12-120 f 2,2 and the 15-150 f2,8 both vignette strongly at their widest, the 12mm nearly circular, the 15mm much less so. The larger zoom has maximum corner vignetting between 25 and 30mm. Probably internal baffles rather than the aperture that causes hard vignetting . Interesting as an experiment with a big zoom ratio, but not very compact and hardly a substitute for a pair of fixed focal length lenses.