… - just a little note which might be interesting to all using some of the Schneider enlarger lenses as a film scanner lens. At least the two Schneider lenses I own feature an illuminated f-stop display, marked in the image below by a blue arrow:
In normal use as an enlarger lens, this f-stop display is illuminated by a small lightpipe from stray light coming from the enlarger’s lightsource. The entrance pupil of the light pipe is a red plastic block on the reverse side of the lens (marked in the image below again by a blue arrow):
If you use these lenses in scanning applications, chances are that ambient light enters via the f-stop display and illuminates the sensor with unwanted additional light. You might want to cover this light pipe with some black tape or appropriate ink.