Re: [Leica] Defective Lens

[Colin <colinmi@fast.net>]

Dan Post wrote:
> 
> Maybe I am just too easy going, or maybe I need my Prozac dose adjusted! The
> miniscule spots in lenses are often unavoidable. I have seen the fine flakes
> of black barrel coating in many lenses, and I have found that they rarely
> affect the image. Are these flaws inherent in the process, and do they have
> an effect? maybe Leica Q.A. knows something we don't consider- that these
> 'flaws' have no effect on the photo. I have seen a couple of bubbles in the
> wide eye of my Elmarit 135, but never gave it a thought. Would these count
> as cosmetic flaws?
> What gets me, working in a camera store, is the huge number of people who
> come in wondering why they have a hazy flair on their prints, and when they
> present their cameras, they have a crusty deposit of dust, fingerprints, and
> lord only knows what else on the lenses! These folks have a serious problem!
> Seriously, though, has anyone done any testing to see at what point 'spots'
> would affect a lens' resolution and sharpness? By spots, I means something
> like .2mm opaque spots (ink?) on the lens. How many needed to degrade a
> lens. I know that random bubbles have no effect, but if there were enough,
> it surely would degrade the image. Points to ponder.
> Thanks,
> Dan'l

Dan,

I agree wholeheartedly with your last post.  I was a bit afraid to say
these things previously for fear of it being considered blasphemy by
some of the more radical elements of the group.  ; )

Nikon customers can be just as obsessive.  We once had a customer
looking for a brand new 80-200 2.8 without any dust in it.  After
examining at least 6 lenses he finally settled on one that looked a
little better than the others.  He drove us nuts but eventually spent a
lot of money.

One demonstration that will make one worry less about specks is to take
a dime and lay it on the front of a lens (a 50 1.4 works pretty well)
and with the SLR pointed upwards, looking through the viewfinder, the
dime is pretty much invisible.  I'm sure a dime would degrade the image
a bit, but not as much as most people think.  (On an M camera I usually
put a silver dollar on the lens, that really impresses them.  ; ) )


Have a good day,

Colin