Archived posting to the Leica Users Group, 2001/02/04

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Subject: [Leica] Re: Min. focus accuracy of Leica lenses and the Hexar RF
From: Akhil Lal <akhil.lal@bcc.cuny.edu>
Date: Sun, 04 Feb 2001 18:29:51 -0500
References: <NBBBIDNIGLFOKNLJCPLHMEHCFEAA.ddh@home.com>

Recently, there was a thread regarding the Hexar on the Rollei list.

Bob Shell, former editor of Shutterbug, stated that Konica have
intentionally set the Hexar's back focus to be 0.01mm/0.01inch (it was
not clear which) longer than the Leica M's. I assume he got this
information from official sources.

Another list member stated that Konica UK have acknowledged this
difference and, upon request, will adjust the backfocus of the Hexar
body to Leica M specs. Then the Hexar lenses need to have their infinity
stops adjusted to focus properly on the readjusted Hexar body.

Please note I have no firsthand knowledge of this  - I'm only reporting
what was posted on the RUG.

Tom A., Erwin, Sal D., LUG'ers/LEG'ers with "inside" info, can you shed
further light on this issue ?

Regards,
Akhil

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

Replies: Reply from "Sal DiMarco,Jr." <sdmp007@pressroom.com> ([Leica] Re: Min. focus accuracy of Leica lenses and the Hexar RF)
In reply to: Message from "Dan Honemann" <ddh@home.com> ([Leica] Min. focus accuracy of Leica lenses and the Hexar RF)