M6/ZM 25/2.8 close focus issue

[E_Aiken]

when focusing my ZM25 at extremely close distances, the lens rotates beyond the capacity of the rangefinder images - I turn the barrel, yet the split images stay where they are. This does not happen with any other lenses I own. Is this a defect, or does the Zeiss lens simply focus close enough that it exceeds the Leica rangefinder's throw?

 

[SDK]

The latter, the lens decouples from any RF camera at 0.65-0.7M (1.0M on M3) because Zeiss designed it to focus closer. Why is a mystery, since even the new Ikon can't maintain focus coupling or parallax correction down to 0.5M. So you have to guess at focus and framing in the close up range. The ZM 21 and 28mm and Leica 21mm/3.4 Super-Angulon also share the quirk.

 

[E_Aiken]

SDK, thanks. Was a little worried there that my camera was going to have to go in...