Re: Character of lenses (TECH-3D digest 209)

[T3D Bob Howard <bobh@xxxxxxxxxxxxxxxxxx>]

RE: John B. comments on mention of 'better character of classic 
lenses"?
This was an 'expopse' article in Techniques Magazine, formerly 
Camera  and Darkroom Techniques, I believe. But it was old hat to 
readers in Japan and myself who has read the English language 
Japanese magazines. The gist of the arguement which can apply to any 
lens not just classic or computer designed, is that all the 
abberations are not eliminated and how the designer chooses to treat 
what remains govers the "flavor" which is what the Japanese use when 
translanted. This has to do with how pleasing the image is 
photographically. The most common example is that a whiz bang 
computer designed lens may have eliminated most of the faults but 
exhibits, what in lens chart testing is noted as 'false resolution'. 
ie. when a bar is so out of focus it becomes two bars and looks 
resolved but is a false imagae because the chart did not  have that 
many lines. In photos this often shws up and ugly rendending of out 
of focus twigs etc. Also some lenses tend to have images that are 
hard and seem over contrasty. Probably a large core Airy disc with 
poor resolution but great contrast.
Around 1965, I sent a basketcase Canon R-2000 I had tried to fix, to 
Canon in Japan and for a lark addressed the package to the President 
of the company, and mentioned how I was a fan of the rangefinder 
Canons and had tried to fix this early SLR. I expected an estimate 
but instead got back a fully repaired camera by air and a just 
published lens manual in English. This had quite a bit on the subject 
of the 'flavour' of a lens, that old photographers recognized. It 
also convince me that Canon knew more about lenses that Nikon.
The problem being hoard of wet behind the ears engineers with 
computers but no experience as photographers. Leica by the way goes 
to extremes in this by making lenses with curvature of field to gain 
other features (since flat field means nothing except to a copy 
camera), but this hurt them in magazine lens tests with charts, which 
the crafty Japanese often made flat field to test well and perhaps 
lost something else. So lens making is an art as well as craft. 
And when you consider the effects of centering and tilt, it is a 
wonder that any zoom works! Bobh


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