I was just sent the link below and thought it worth
passing on .
Harping on about when I lectured again, I would often find students
grumbling about the lenses in the photo store (we lent out camera kits), blaming
them for their fuzzy images or the white spots on their prints. More oft
than not it was their poor efforts at focusing their enlargers or rough handling
of negs - but they'd decline to see it. If I had the time, I'd whip
off a print to show them their neg was in fact fine, their lens fine, and they'd
be better off spending time paying attention to their lecturer in the darkroom
classes, try to focus the enlarger and maybe occasionally store their
negs somewhere other than the bottom of their bag .. If I had less time I'd
wave a cat lens at them and ask them if they thought the big black circle in the
front of the lens would degrade the image quality <blank stares>.
Sometimes I'd demonstrate (less dramatically than the link below) that
since nothing in the optical pathway was in focus, the gunk they saw on their
negs, film, scans, prints or whatever was more a consequence of mistreatment of
the negatives than anything relating to the lens - and I showed this by sticking
a piece of electrical tape across a lens - white demonstrated a general lowering
of contrast - black showed basically a reduction in light levels .. and I tried
to tell them THAT was why you fixed deep scratches in a lens by painting
them black ! =)
A decent box lens hood could almost eliminate the
net effect of a piece of white tape.. and overall, a lens hood went a lot
further to preserving maximum contrast and sharpness than giving the lens a good
clean ever did ;)
