[Leica] step up ring

[alexolstein at comcast.net (alex olstein)]

Hi Bill,

If you are handy,  you can get a cheap 40.5mm step up ring,  and gently file 
the threads a bit to reduce the .5mm ( emery board is ok ) .  You don't have 
to measure,  just file a bit and try it on the lens,  and then just file a 
bit more, etc. the thread pitch should be the same so what happens is the 
cheap ring is usually made of aluminum and the lens is usually brass,  so if 
you file the threads a little the aluminum step ring will be "cut" by the 
brass lens and so it will fit enough to work.  The tolerances on the cheap 
rings are often  so large that is to your advantage. 

Alex Olstein