[Leica] Re: DR summicron and M4-P

["Michael D. Turner" <mike@lcl-imaging.com>]

Pieter Bras wrote:

> Peter Niessen <niessen@ifh.de> wrote:
> >
> >I understand that when changing a DR Summicron lens the focus _has_ to
> >be set to infinity. I do not know why, though.
>
> Take a look at the rear of the focusing mount. There is a cam that
> engages the camera's rangefinder mechanism.  Usually this is just a
> single surface, but in the case of the DR Summicron, there are two
> sections, separated by a step.  The protruding section is for the
> near range.  However, when the lens is in the normal range, this near-
> range cam protrudes beyond where the rangefinder's follower (the little
> wheel) can move.  If you try to mount the lens when it's focused at the
> short end of its normal range, there is a good possiblity that the
> near-range cam will engage the follower, and bend it out of position.
> This will result in a misaligned or damaged rangefinder.

> I learned this the hard way, by mounting my DR on an M4-P when it was
> focused to about one meter.

Pieter, I've been following this thread with interest for some time, since
I have a DR and an M4.  I have never experienced this problem. When I read
the above, I did some experimenting. With my DR/M4, I note that the cam
does indeed protrude, but not at all beyond where the follower can move. In
fact, that is where the short focus range begins. The only anomaly I see is
that in rotating the lens to the locked position, the follower will
suddenly drop into the gap next to the near-range cam. Perhaps there is
some difference in the travel range of the follower between the M4-P and
the M4? So far as I can tell, there is no problem at all mounting the DR on
my M4 no matter where the focus is set.

>

- -Mike