Take test shots (at all apertures, both in and out of focus) to assess the
effect of the damage to the lens - you might be lucky and merely get a bit
of a light 'mist' effect which can be dealt with using appropriate software.
If you're really lucky, at some apertures, it may not even be noticeable
without close examination. You could be fortunate the damage is to rear
lens. If light is refracted, it wont be moved from where it should fall by
much.
Look at it like this to see what I mean:
------ Front glass (scratch on front
glass)
/\
/| \
/ | \ (possibly large displacent)
---------- Rear glass
--|---|----|--- Film plane
------ Front glass
|
|
|
---------- Rear glass (scratch on rear
lens)
/|\ (possibly small displacement)
---|-|-|---- Film plane
If a vertical line were the proper path, you can see that a scratch on the
front of the lens would mean a larger displacement from the proper path by
the time it reached the rear of the lens. But from the rear of the lens to
the 'film plane' may be small enough that the light path hasn't deviated by
much.
Another possible effect could be just (or and) some false colours due to the
damage since the blue and red ends of the spectrum may refracted differently
by the damage.
You may also be lucky in that the damage seems to be mainly just below
centre (near the area where the rays are normally refracted least by the
lens - which may help reduce the effects of the damage). Unfortunately, it
is the are where most people and cameras usually focus and meter most with.
Can you see the damage when yoiu look through the viewfinder? If you can see
it, so will your film/sensors. If you can't see it, then you might be lucky
enough to still get decent pictures.
At worst, you can try re-selling the lens to recover your losses (at least
to some extent).
Allan
PS No trees were harmed in the sending of this message and a very large
number of electrons were asked their permission to be terribly
inconvenienced. (And threw a party for them afterwards for being really cool
about it).
Disrupting the unnatural balance that you, as a conscious human being and a
confused mass of energy, have created.
-Disturb the mind -
>From: Moose <olymoose@xxxxxxxxx>
>Reply-To: olympus@xxxxxxxxxx
>To: olympus@xxxxxxxxxx
>Subject: [OM] Re: ( OM) Photographs of lens damage
>Date: Sat, 04 Nov 2006 03:45:31 -0800
>
>Brian Swale wrote:
> > Hello all
> >
> > Recently I bought at an auction, a Zuiko 21/3.5, knowing it had some
>kind of damage
> > to the rear lens element. I did not know what kind of damage and could
>not ask as the
> > auction was closing soon after I discovered it.
> >
> > It arrived yesterday, and I found the damage was right into the glass.
>Looks as though
> > the rear lens cap has come off while the lens was joggling around loose
>in a camera
> > bag, and rubbed against something hard. Cleaning does not shift the
>marks.
> >
> > http://homepages.caverock.net.nz/~bj/photography/zuikoholics/recent5.htm
> >
> > It will be interesting to see if this damage has any discernible effect
>on images.
> >
>Oh, bad luck, Brian, I'd hoped it wasn't so much damage. It will almost
>certainly affect images if left as is. Light will be refracted and
>reflected and cause at least flare, if not actual bright spots.
>
>T'were mine, I would cover the inside of the damaged areas with
>something black, finepoint Sharpie ink, perhaps, to kill reflections and
>refractions from the rough edges. It's possible that there will still be
>a darker area in images, but that should be easier to correct. Perhaps
>with a retrofocus design, where the rear node is actually behind the
>rear element, even that won't happen.
>
>I know you aren't into post processing and have computer limitations.
>Still, one possibility if there is a darkened area would be to take an
>image of a simple white subject, reverse it, and make an exposure
>correction mask that just compensates exposure where it is affected. by
>the damage.
>
>The other thing I would do is keep an eye out for the same lens with an
>undamaged rear element but with damage elsewhere which renders it
>inexpensive.
>
>Moose
>
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