Re: [Leica] resolution versus contrast?

[DonjR43198@aol.com]

In a message dated 4/20/99 12:49:40 PM Central Daylight Time, 
imxputs@knoware.nl writes:

<< Subj:	 [Leica] resolution versus contrast?
 Date:	4/20/99 12:49:40 PM Central Daylight Time
 From:	imxputs@knoware.nl (Erwin Puts)
 Sender:	owner-leica-users@mejac.palo-alto.ca.us
 Reply-to:	leica-users@mejac.palo-alto.ca.us
 To:	leica-users@mejac.palo-alto.ca.us
 
 DonjR43198 wrote:
 >The move from placing greatest emphasis on resolution to placing more
 >emphasis on contrast and reducing resolution to achieve that goal was 
pointed
 >out in some of the Leica literature in the early 60's when Leica began to
 >market the lower resolution 50 mm Summicrons.  The brochures actually
 >illustrated this with side-by-side comparisons showing that the eye 
perceived
 >high contrast but lower resolution as the sharpest image.
 
 >It would be very nice if Mr. Puts would undertake to compare the resolution
 >of the old D-R Summicron with the present day Summicron.  The ones I have
 >tested show the D-R Summicron sporting a center resolution of 112-120 lpm to
 >about 80-88 lpm for the current Summicron lenses.  Further, the studies I
 >have seen from the laboratory of Mr. Puts are conducted using color film
 >rather than Tech Pan or a microfilm.
 
 >If the current Summicrons really outperformed the D-R for resolution, I 
would
 >have one on my M cameras but there have been no "figures" published, at 
least
 >that I could find, that show the current Summicrons will resolve even 100
 >lpm.  Maybe this discussion will result in such figures being located or
 >determined or at least generate some discussion.
 
 >Should you have some "figures" rather than subjective comments from various
 >testing organizations, I would very much like to see them.
 
 There are several topics here. In the past there was indeed a balancing of
 resolution versus contrast. The state of aberration correction in general
 is such that there does not exist one sharpness plane of best focus, but
 many. Every focus plane gives a different size of the spotdiagram and
 therefore a different recording of a point. By shifting the focus plane one
 could give more emphasis on resolution (smaller spot size, but more
 diffusion around it) or contrast (bigger spot size but sharp edges).
 Recently the designs have evolved to a situation where resolution AND
 contrast are both at the same time feasible. Naturally modern Leica lenses
 exhibit this trend.
 I did analyse the resolution the resolution of the DR and the current
 Sumicron as I said in my comparison report. I refuse to give figures
 because they are irrelevant for a serious assessment of image quality and
 would only revive the older and obsolete discussions.
 I wonder which studies from the "laboratory of Mr Puts" you have seen to
 warrant the conclusion that I use color film rather than TP or microfilm.
 To be sure the current Summicron will outperform the DR in all aspects
 including resolution.
 
 Erwin
 
 
  Date: Tue, 20 Apr 1999 19:44:17 +0200
 To: leica-users@mejac.palo-alto.ca.us
 From: Erwin Puts <imxputs@knoware.nl>
 Subject: [Leica] resolution versus contrast?
 Sender: owner-leica-users@mejac.palo-alto.ca.us
 Precedence: bulk
 Reply-To: leica-users@mejac.palo-alto.ca.us
 
  Good evening Mr. Puts:  You asked where I received the notion that you used 
Kodachrome film in testing some of the Leica lenses.  There is a wonderful 
post at Author: Erwin Puts email: <imxputs@knoware.nl>  relative to the new 
135 mm lens that has a sentence that reads:  " All test pictures made on 
Kodachrome 25 and 64!! "  In addition there was another wonderful examination 
of the 35 mm lenses with the notation "But handheld shooting and the grain 
limit of the films used (Kodak Ektachrome 100 SW and Fuji Provia 100) 
possibly suppressed this potential advantage."  In your same paper you 
examine the 50 mm Summilux and you write:  "For my formal comparison shots I 
use Kodachrome 25 and 64, as these films still give the best sharpness (read
contrast) for very fine image details."  These articles were followed by the 
following:
Copyright (C) 1997-1998, Photosite All rights reserved. Author: Erwin Puts 
email: <imxputs@knoware.nl> Last Updated: Saturday, November 28, 1998 

The above quoted references to Kodachrome in your articles led me to believe 
Kodachrome was employed as the film medium.

I consider your work most authoritative and hang on every word.  It would be 
appreciated if you would let us know exactly which film or films you use in 
analyzing Leica lenses.  

Thanks again for your most interesting posts!