Archived posting to the Leica Users Group, 2001/01/19

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Subject: [Leica] resolution limits
From: Christer Almqvist <christer@almqvist.net>
Date: Fri, 19 Jan 2001 19:10:58 +0200

I came across a small handbook from Fuji that had a formula for 
calculating overall resolution and here it is if somebody is 
interested.

1/R = 1/r + 1/r + 1/r  etc

"R" is the resolution of the total system and the "r"s are the 
resolution of individual factors. In the formula the "r"s are 
indexed 1 and 2 and 3 etc., but I did not think I would manage to 
write this into the e-mail, so I did not try. Instead, look at a 
practical example.

If the lens has a resolution of 200 (Lpm) and the film a resolution 
of 50, then the overall resolution is 40 calculated with the above 
formula as follows.

1/R = 1/200 + 1/50

1/R = 1/200 + 4/200

1/R = 5/200

1/R = 1/40  and R is thus 40 (Lpm)

To me this means that you will get the best payout in form of 
improved technical picture quality if you get working on the weakest 
point in the chain. This probably seldom is your lens, if you have a 
Leica, even if it is non-asph. I wonder how many lines a shaky hand 
can resolve, and how many a steady hand.

Sorry if you knew this already. Now go back to shooting film.

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