Found a Summicron in a camera bag

[Ronald M]

I would worry about potential changes in focal length and overall optical performance, but I don’t pretend to know much about Leitz lenses specifically. That said I don’t think it’s good policy unless a glass is so severely compromised its usability and ability to be repaired is grim.

Would you be informing potential buyers about the absence of originality in the lens you’d be selling? Because if not I think it’s unconscionable. If it was mine I would keep both lenses original and have the affected one cleaned.
Cheers
Brett

Agreed. Do not make a mutt of two lenses. Value of both will be near zero.

They are exactly the same optically, only the tolerance in final focal length may be different.

The DR will not work with digital Leica whereas the Rigid will. My Rigiid is a gem on the M9.

 

[Phil_F_NM]

The DR will work well on the M9 but has to be mounted in close focus range. The plastic tab on the "eyes" needs to be either shortened or removed altogether.
If this lens is to be used as an "investment" then the optical heads should be kept with their original helical assemblies but if it is to be used for actually making photographs, do as you will. Swap to your hearts content. You nor anyone else won't be able to see the differences between the optics. Don't be afraid of using gear to suit your purposes.

Phil Forrest