Collapsible compatibility list
I seem to have a problem with multiplying collapsible 50mm lenses. Tonight I would measured their collapsed depth and checked collapsible compatibility with my IIIG, M240, Bessa T and Sony A7RII.
1932 Nickel Elmar LTM=20.1mm M-Adapter 19.1mm Fits the 240, IIIG, Bessa T and looks like it *barely* fits the Sony. Sony is very very close though.
Industar/Fed 10 LTM=19.2mm M-Adapter=18.2 Fits them all.
Elmar 2.8 LTM=19.9mm M-Adapter=18.9 Fits M240 and IIIG. Throat is to wide for Bessa T and it is also very close with the Sony.
LTM Summicron LTM =13mm M-Adapter=12mm Fits them all.
Red Scale Elmar LTM=22.1mm M-Adapter=21.1mm Fits IIIG and M240, doesn't collapse in the Bessa T or Sony.
Hexanon 50mm 2.4 LTM=13.27mm M-Adapter=12.27mm Fits them all.
Elmar-M 2.8 LTM=NA M-mount=20.8 Only fits the M240.
The Sony is hard to get an exact measurement to the shutter as it is normally open. The shutter isn't flat either as there are what looks like rivet heads at various places on it which raise it up slightly. Anything that is really close is probably a little too close to use that way without an o ring or something on the lens barrel to give it more clearance.