DR Summicron incompatabilities

["S. Khai Mong" <khai@iware.com>]

I have a problem removing and putting on my DR on the M6 when focussed
at 3'4".   My lens is #1587840  M6 is 2288xxx.  At least my mystery is
solved for me.

(I am not sure about terminology.  In the following description,
Cam-follower is the thing inside the camera, the cam is the the thing
inside the lens.  Somebody please enlighten me on correct usage).

After examining my DR and M6 rather closely, I can see and feel where
the problem is. When lens is focused at 3'4", and when I try to put on
the lens, the cam in the lens attempts to push the cam-follower to its
most retreated position.  But there is a stop limit on the
cam-follower, and because of that, the bayonet flange won't touch its
counterpart flush on the camera, and you can't turn more than a
certain amount.

The reverse is true when trying to dismount with lens focused at 3'4".

However, once it is on, you can move to 3'4" because when mounted, the
cam-follower just touches the "indented" part of the cam.  And also,
when mounted, you _can_ move to the close focusing distance.  This is
because just turning that much retracts the cam into the lens, just
giving it enough clearance for the cam follower to retract all the way
back into the camera, which it couldn't do while mounting.

Now I don't know why my M6 cam follower can't retreat all the required
way back.  Perhaps because it is a late model, perhaps it is
manufacturing tolerance.  But one thing I did notice was that the stop
on the cam-follower on the M6 is different from my M3.  The one on the
M6 is best described as looking like an off-center washer, and also
bigger than the one on the M3.  The off-center is such that it would
definitely allow the cam-follower to retreate less than what would be
if the same style of stop as an M3 was used.  The stop on the M3 looks
more like a circular, regular washer, smaller than the one on M6.

- -- 
S. Khai Mong           Imageware Inc, 323 N. First St, Ann Arbor, MI 48103
Email: khai@iware.com                                Voice: (313) 994-7301
WWW: http://www.iware.com/~khai                        Fax: (313) 994-0802