[Leica] Re: DR summicron and M4-P

[pieter@world.std.com (Pieter Bras)]

Michael D. Turner <mike@lcl-imaging.com> wrote:
>
> 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.

Apparently the rangerfinder was redesigned ("cost-reduced" to put it
politely) when the M4-2 was introduced, and this is the same design as
on the M4-P and M6.  So it may be possible that older rangefinder
mechanisms allowed enough travel to avoid interference between the
near-range cam and the follower.  There may also be some unit-to-unit
variation in the amount of travel in the RF.

The danger zone is in the normal range between 1 and 1.2 meters (I have
the later dual-scale version of the lens).  If you try to mount the lens
in this range, it will feel that something is binding.  If you try to
dismount the lens, it will get hung up and won't come off.

As for climbing and descending the step between the near- and far-range
cam sections, that shouldn't be a problem as long as the follower is
capable of moving freely over the entire height of the step.  It does
this normally whenever the lens is switched between the near and far
ranges.

BTW I was aware that the M6 instruction book warned about mounting the
DR Summicron except at infinity, but there was no such mention in the
M4-P manual (red cover), so I'd assumed it was an M6-specific problem.
It isn't.

- -- 
Pieter Bras