Kennedy wrote:
> Dr. Matthew J. Cordery writes
> >I'll just say that my 50/1.8 has one black flec on a rear element and I
> >haven't noticed it in any of my slides.
> Of course you won't, as one of my old lens designers says :
> "Lenses are for looking through, not loking at!"
> The 'scientific' support for his one liner is two fold, but fairly
> straight forward. The black spec merely prevents a small part of the
> lens from contributing to the image, it doesn't add any light of its
> own. That why if you scratch a lens the best policy is to paint the
> scratch black so that is doesn't scatter light and reduce performance.
Does this apply to internal elements as well? On one of the lenses that
comes with the cameras I'm considering purchasing (135mm f2.8), there's
a
small strange looking wrinkle on the second element (HA! I'm learning
camera
terms ;) ) from the front. It looks almost as though it were a 2mm
round
piece of peeling transparent skin. I can't see it from the viewfinder
when
I put the lens on the camera body (something else I've had fun learning
how
to do...) and it doesn't show up when looking through the lens from the
back.
It hasn't affected any of the pictures I've taken so far with the lens
(around 72 of them), but I'm a bit concerned that this might be a sign
of some
sort of subtle abuse.
It doesn't appear to have been dropped, caused by a fungus, or anything
else
mentioned in Mr. Hawkins' FAQ (quite informative, BTW). Severe
temperature
change maybe? Just old age - it's supposedly around 12 years old?
Other
than this flaw, the lens is spotless. I looked at the other two lenses
that
come with the cameras and they're equally well kept but without obvious
internal
problems.
I don't really think it constitutes a deal-breaker - In fact, I might
use it
to shave a few more bucks off the price (HA!). However, I'd be
interested in
anyone's thoughts on what causes this, whether it's worth repairing, and
how
much it might cost in the long run...
Best,
Bethany
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