Re: [Leica] adapter problem with 15mm Heliar

[Ken Iisaka <kiisaka@pacbell.net>]

> Hello all,
> I recently picked up the Voightlander Heliar to use mostly with my M
cameras.
>  I've tried two aftermarket adapters but the lens does not line up at
the 12
> o'clock position when mounted with the adapter.  This has led to
> underexposure problems of 1-2 stops!  I know this was discussed a
while back,
> but I can't seem to find the answer in my digests.  I tried the
adapter on a
> Skopar at my local camera shop, and that combination lined up at 12
o'clock
> just fine.  Could it be that my lens has a flawed mount?  I would be
grateful
> for help from others who have had the same problem.  I remember
something
> about using sandpaper -- was it on the adapter or the lens?  I'm not
very
> mechanically adept, so I hope the solution isn't too drastic.

I don't see how slight misalignment can cause underexposure, but my
experience is as follows:

I've found that with a non-Leica Japanese adaptors, I found the
alignment to be inconsistent.  When I bought my 15mm,  I asked the shop
to let me choose from 5 adaptors, and they were all over the place.  I
asked them to bring out a genuine Leica adaptor, and the alignment was
right on the money, with 3 of the lenses they had on the shelf.

What I have observed is that non-Leica adaptors are not finished as
precisely as Leica, and not only causes slight misalignment described
above, lenses do not mount quite as tightly: after screwing in the lens
until the mounting surfaces meet, you can screw in further perhaps
another 5-10 degrees.  With a Leica adaptor, you cannot screw in further
at all.  The mating is much tighter.  This is due to differences in the
level of flatness of the mounting surface.

Needless to say, I bought the Leica adaptor, and have been happy.