Archived posting to the Leica Users Group, 2001/05/13

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Subject: [Leica] Testing notes and questions.
From: Dante Stella <dante@umich.edu>
Date: Sun, 13 May 2001 14:38:26 -0400 (EDT)

	1.  When you are tesing a 21mm lens, is there a customary distance
(say, some multiple of the focal length) at which you check for fine
detail rendition?  Usually, I shoot at a skyline with varying distances,
and the way I judge lenses is by the smallest thing (like, say a facade
brick or a limestone caulk seam) that comes out.  This seems to have
failed me with 21s, since it seems that what I normally use to check
overall quality are now smaller than film grains.

	2.  For people who heavily shoot 21s, is the game just to focus on
something in the foreground and let everything else fall in?  I am
beginning to get the idea that slavish devotion to focusing at infinity
wastes the DOF on objects too small to render well on film.

	3.  Can someone recommend the finest-grain development regime that
keeps TMX's speed at 100 and its curve as straight as possible?  I usually
use hyperdilute Rodinal or 1:1 Xtol, but the former changes the toe and
shoulder, and the latter may be too grainy for testing lenses.

Testing Notes:

	1.  I just got finished running identical tests with two bodies
for focus and RF operation, using an M3, a Hexar RF, a 21 Kobalux, a 35
Summicron, a 50 Hexanon and a 90 Hexanon, using all lenses on both
cameras, shooting from 2.8 to 16 on all of them.  RF alignment was
absolutely identical between both.  I will report back on whether one
body produces sharper pictures than the other.

	2.  Hexar metering - for the M3 shots, I established an exposure
of f/16 and 1/30 (and equivalents) by using a Zone VI spotmeter on the
street and setting the street to Zone V.  When I reshot all of the tests
with  the Hexar, AEL produced this same basic exposure with all four
lenses,  and did  not deviate at all.  This was true even with the
non-retrofocus 21.  So is  this oft-discussed superwide metering problem
just with the M6?  Or is  there some circumstance in which both cameras
would fail to meter correctly?  Is this a problem with the CL/CLE?

Have a great day!
Dante

Replies: Reply from Christer Almqvist <christer@almqvist.net> (Re: [Leica] Testing notes and questions.)