RE: [Leica] focus inaccuracies: my test results

["Henning J. Wulff" <henningw@archiphoto.com>]

>Dante,
>
>>  If you read Dan's post, it said that BOTH cameras (M6 and Hexar)
>>  decoupled at the closest distance the lens RING would go to.
>
>Actually, I said that only the Hexar RF decouples at the closest distance
>the focus ring turns to; the M6 remains coupled through the entire throw,
>and the 35 and 50 focus accurately on the M6 as a result (but not on the
>Hexar at min. distance).  The oddball is the 75, which won't achieve the
>correct focus until 2.5 feet (roughly .75 meters) on both cameras.
>
>I have it from a reliable source that the Hexar RF coupled with Leica lenses
>will either be accurate at infinity OR at < .7 meters, but not both.  So you
>have to decide how you want the rangefinder calibrated on the Hexar and
>shoot accordingly.  Obviously, the best choice is to align infinity and then
>restrict yourself to > .7 meters when shooting up close and move the camera
>to/from the subject to focus rather than turn the ring.
>
>I've also heard (same source) that this is true of the 75/1.4.  At least I
>know how my lenses and cameras behave at these distances and so can
>compensate; the good news on my 75 is that < .75m it consistently focuses
>1.5 inches too close, and so if I focus on an ear instead of an eye at that
>distance, I've got the eyes in focus.
>
>Dan

After reading this about the 'decoupling' of the rangefinder, I 
decided I better check myself on some of my gear. Delta 100 in Xtol.

So - 4 bodies, including a 1990 M6, an M6TTL .85, an LHSA .72 and a 
Hexar, and various lenses including 50/1, 75/1.4 and 90AA plus 3 
others between 50 and 135.

I checked at infinity, 3m, 1.5m, 1m, and for the 75, at .8m(closest 
marked) and at the near focussing limit. I have a macro slide that I 
used to focus the cameras after setting the lens to the closest 
physical distance.

The result? Satisfaction throughout, except for the 90AA, which tends 
to focus on the distant DOF side with the .85. It's fine with the 
other bodies. The Hexar is a little bit harder to focus than the 
others, but the on-film results were as good as those with the .85. 
In my case no rangefinder uncouples at any distance, and the Hexar 
was no worse than the .85.

BTW, the only camera body of these that had been fully adjusted was 
the 1990 M6, which used to have a problem with close distances, being 
off about 7cm at 1m.

So: 2 hours of testing and developing; now back to shooting and no 
more testing until I whack something seriously , which of course 
could be tomorrow.

As an aside, the LHSA camera is the smoothest M I have ever used; the 
only thing that compares is a well-used and adjusted M3.

- -- 
    *            Henning J. Wulff
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