I've got a Nikon S2 and a couple of lenses, but one thing I can't figure out is how to safely carry my 50mm lens when I switch to my 35mm. Since the 35 mounts to the outer mount, it's totally different on the back end than the 50mm.
I'd like to carry the 50mm off-camera sometimes, but not until I figure out how NOT to scratch up the rear lens element.
So what are all you other Nikon/Zeiss RF users doing?
Rear lens caps for the 5.0cms are hard to find - but not impossible.
Many S2's were sold to Japan-based GIs as kits, apparently with the 5.0cm lens already mounted (or, anyway because the purchaser "tossed" it" thinking he'd never need it again!).
I suspect many of these buyers treated the camera as if it were a fixed lens one so never needed to dismount the 5.0cm and thus saw no need to keep the rear lens cap.
Search eBay and every once in a while one will pop up. You'll pay a crazy price but it's what the market will bear.
One alternative I've used is to find a plastic cap that is deep enough to accomodate the rear element. It will probably be too wide to fit snugly so then use rubber bands to hold it in place.
Not very convenient - but it will protect the element.
EDIT: I wrote this before I saw patrickjames post. I'm going to check out that supplier myself. $9 is a bargain!