Hi Alex:
<< You raise some rather profound points--is it possible to
retro-blacken ANY (or even most lenses) via a competent repairman? >>
Maybe. Adding paint increases the diameter of the element. That might
make it hard to fit back into the assembly. And if its put back in wet,
you might never be able to disassemble it again.
<< wouldn't Olympus blacken ALL OM lenses past a certain point? Was this
something they gradually (over months or years) put into universal
production--as in MC? >>
Oh, I suspect that it it needed blackening, they did it from the start.
I think it is only a concave surface lenses which has to be blackened.
They will refract light onto the edges of the element. If they bounce
back into the glass, you have yourself flare. You need a very matte
black surface to prevent that. Some reasons that a lens might not be
blackened enough is water damage (looks like white spots on the edges of
one or more elements) or fading or just not black enough paint.
<< Also, may I ask exactly which projector lens you modified? >>
I had it professionally done. It's:
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1264492805
Navitar uses what appeared to be the ink from a permanent marker to
blacken the edges. It disappears under alcohol solvent. Not too swift
of them, especially since this is a lens which carries a US$890 list
price ($599 mail order).
Our resident repair gurus can tell us more about edge blackening, if
they desire.
Gary Reese
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