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

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Subject: Re: [Leica] Testing notes and questions.
From: Christer Almqvist <christer@almqvist.net>
Date: Sun, 13 May 2001 23:58:32 +0200
References: <Pine.SOL.4.33.0105131420010.25765-100000@breakout.gpcc.itd.umich.edu>

>	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.

I used to frown upon people shooting newspaper pages for lens 
testing, but I have to admit it has one advantage: results are 
comparable. To make them comparable, also between different focal 
lengths, always shoot at a distance of (say) 50 times the focal 
length.  The newspaper page will then be the same on all negatives 
irrespective of what focal length was used. I found 50 times a 
practical figure, I can do the shots indoors even when I test a tele. 
Using a factor of  100 times and  a 135 mm would take a house bigger 
than mine.

But shoot some real life scences too!
>
>	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.

I prefer Delta 100, but I agree with you with regard to the 
developers. Xtol gives me the straightest curve, or shall we calle it 
"line" because that is what it is.


>
>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

- -- 
Christer Almqvist
D-20255 Hamburg, Germany and/or
F-50590 Regnéville-sur-Mer, France

In reply to: Message from Dante Stella <dante@umich.edu> ([Leica] Testing notes and questions.)