[Leica] Min. focus accuracy of Leica lenses and the Hexar RF

["Dan Honemann" <ddh@home.com>]

When shooting some test slides (velvia, if it matters) with my new Hexar RF
and 35/1.4 asph, 75/1.4, and 50/2, I noticed that all three lenses focus
closer than their min. focus mark on the lens.  I also noticed that the
Hexar rangefinder does not register the last 1/8" turn toward the closest
distance.  My .72x M6 TTL rangefinder does move through the entire range,
however.

The results of my first test--a ruler and newsprint at a 45 degree angle,
widest f-stop and min. focus distance for each lens, focused on the 6" mark
on the ruler (shot with tripod and cable release, of course)--show that the
35 and 50 are right on the money with the M6, but the 75 consistently
focuses on the 4" mark instead.  The Hexar RF, on the other hand, is
consistently off by 1.5" (too close), with sharpest focus at the 3 1/2" mark
with each lens.  (By the way, I often shoot wide open, and very often at
min. focus, so these aren't just trivial tests for me.)

I performed the first round of tests with the SF 20 flash, and the Hexar
slides were a bit overexposed, so I just did a second round with natural
light.  That's when I noticed that the Hexar rangefinder does not engage
with the last small twist of the focus ring toward closest distance.  I'll
shoot a few frames with the lens set at the closest distance mark tomorrow
as well, to see if this makes a difference.  I should have results back by
Thursday.

I'm left with the following questions for now:

1. Does the fact that the lenses turn past the 2.5" (or min. focus distance
mark) printed on their barrels mean that anything closer than this mark is
up for grabs?  Should I consciously keep from turning their focus ring/tab
all the way?

2. If only the 75 mis-focuses on my M6, does that mean I should have the
lens calibrated instead of the rangefinder (not even sure how they would do
this)?  Would having the M6 adjusted for the 75 mean that my 35 and 50 would
now mis-focus up close?

3. Do those of you who own the Hexar RF notice that your RF cam stops
engaging beyond the .7m mark on the lens, with the last small twist not
affecting the rangefinder at all?  Or is something amiss with my Hexar?

Dan