Re: [Leica] Making a back to back lens coupler

[Kip Babington <cbabing3@swbell.net>]

I agree that the Leica device leaves a lot to be desired in terms of rear
element protection when one of the lenses is removed.

I did just what you're thinking of doing, with two N**** caps about 25
years ago, and they're still tight as can be.  I cleaned 'em good with soap
& water to get any finger oil off, and then probably wiped them off with an
alcohol swab, before ladling in a healthy dose of epoxy, holding them
together with fingertip pressure for a few minutes, and letting them sit
overnight.

I have also done the same thing just this past week with a pair of plastic
rear caps for LTM - I have a Russian Jupiter 35mm and one of the
Voigtlander 25mm Skopars, both of which are fairly short lenses that have
deep rear elements.  I got two deep rear caps (for the Jupiter) and glued
them together, and now I can stack a pair of wide angles for my IIIf  in a
single hole in my camera bag, and they aren't any longer combined than my
90mm Elmar with its FIKUS hood attached.

I suspect that epoxy would make an unbreakable bond between two of the new
M rear caps if they were properly cleaned.  Another alternative might be to
use plastic solvent type model cement, available in a small bottle with
applicator brush at any hobby shop (at least in the US).  It flows by
capillary action between tightly fitting surfaces (like the rims of two
rear lens caps being held together) and essentially dissolves the two into
each other.  Most of these cements are pretty quick acting, and set enough
in about 30 seconds to release pressure and not have the parts move,
although overnight cure is often recommended for full strength.

Let us know which way you go and how it turns out.

Cheers,
Kip

Dennis Painter wrote:

> I want to glue two of the latest rear lens caps together to make a back
> to back lens coupler. The grey thing leica sells should be closed and
> deeper for 21mm lens, etc.
>
> I figure if I just glue them tother they will separate, at a most
> inopportune time. Anyone do this and know what works?
>
> It does look like that ridge should be sanded down to improve the
> contact surface area.
>
> TIA,
> Dennis