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

["Dante A. Stella" <dante@umich.edu>]

Dan -

I have this thing happen too with the 35/2 Summicron - when you pass the
nearest focusing mark, the last 1mm (i.e. closer than  doesn't trip the RF's
rangefinder.  I wouldn't expect it to, since the spec close focusing limit of
an M lens cam (as far as I know) is 0.7m.  I would suspect the Summicron has
some "bonus" focusing range.  I approach this the same way I approach focus
with the 50/1.4 LTM Nikkor (which goes down to 18" but cams only to 1 meter) -
just focus from nearest until the RF catches, and then focus with the camera.

Interestingly, the same lens on my M3 does not make the RF move until the lens
hits the 0.8 mark, despite the fact that with a 50 Summicron and 50 Hexanon,
the thing is coupled all the way down to the 0,7m stop on the lens.  Weird.

Dante



Dan Honemann wrote:

> 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