Manuel Viet wrote:
> .....
> [*] side story : I made researches on DIY enlargers long ago, such as they
> were made in the good ole'time to make use of the standard lense of the
> camera to print the pictures ; the supposed benefit being to somehow negate
> some distortions by printing out of the same lense that took the image. I
> mostly came with a 'no can do' advice because the enlarger's heat would
> liquify the internal lube of the lense.
The more optically valid reason is that it's not the right kind of lens.
General purpose taking lenses are optimized for a repro ratio of 1:40.
An 8 in high print from a 35 mm neg is 1:8, much closer than the lens
was designed for.
Most general purpose lenses don't have flat fields, which doesn't matter
much for their designed use. Worse, many have even more pronounced field
curvature at close distances. So even stopped down to the point that
diffraction effects start reducing sharpness, it may be hard to get both
center and edges in focus on the nice flat paper.
Macro lenses are closer to the purpose, being optimized for greater
magnifications and for flat field. At that, though, they are optimized
for different repro ratios than enlarger lenses. And then you can worry
about cooking them. :-)
Of course it doesn't matter these days as excellent used enlarger lenses
are quite inexpensive. Anybody need a Schneider or Rodenstock 80, 150,
180, 210 or 240 mm, just drop me a line. I already sold the EL Nikkor 50
mm to Dan.
Moose
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