The following collapsible lenses have a lens body that protrudes more than 20.5 mm behind the lens mount when collapsed:
- Current/1994 Elmar 50/2.8
- Elmar 50/3.5
- Hektor 50/2.5
- Industar-22 50/3.5 (Note: The FED ‘Industar-10’ fits)
These lenses will foul the interior of the Epson R-D1, and shouldn’t be collapsed fully: Place an O-ring on the lens tube to act as a spacer. These lenses won’t hit the shutter, but instead a protective ledge in front of it—damaging the paintwork and, possibly, producing metal chips.
Most collapsible lenses will protrude less than 20.5 mm (e.g., the 1950s Elmar 50/2.8 and Elmar 90/4 protrude 19.5 mm) and can be collapsed safely but take care not to push the lens upwards when collapsing it, as it can scrape against the camera’s focusing cam (unlikely to cause damage, but best avoided).
Other problematic lenses
Bulky rear elements
Lenses with a rear element that protdes more than 20.5 mm behind the lens mount should not be used:
- Hologon 15/8
- Super Angulon 21/3.4 and 21/4
- Elmarit 28/2.8 (version 1)
Note that the Jupiter-12 can be used despite its bulky rear element.
Thin focusing rings
Some lenses such as the Summilux 75/1.4 or Summicron 90/2 have a thin focusing ring, and there are occasional reports that this ring fails to engage fully with the camera’s focusing cam. Whether such lenses couple correctly with the R-D1 appears to be related to manufacturing tolerances of the lens, the camera or both, so one lens may work perfectly, yet another won’t.