Effect of a scratch on the rear element

What is the effect of a scratch on the rear element of a lens? I'm
looking at a used lens, fast wide angle. I know a mark on the front
element can induce flare, not sure if the rear element is more or less
critical: http://i8.ebayimg.com/02/i/000/d3/24/887f_3.JPG

In article ,
Paul Furman wrote:

What is the effect of a scratch on the rear element of a lens? I'm
looking at a used lens, fast wide angle. I know a mark on the front
element can induce flare, not sure if the rear element is more or less
critical: http://i8.ebayimg.com/02/i/000/d3/24/887f_3.JPG

It's the worse place on a lens to have a scratch, next to perhaps
internally. Dead center on the back element to me would be a deal killer.

--
Reality is a picture perfected and never looking back.

Paul Furman wrote:
What is the effect of a scratch on the rear element of a lens? I'm
looking at a used lens, fast wide angle. I know a mark on the front
element can induce flare, not sure if the rear element is more or less
critical: http://i8.ebayimg.com/02/i/000/d3/24/887f_3.JPG

At wide apertures you would get slight flare, at small apertures you
would probably get a hazy area in the image. Possibly, filling the
scratch with an opaque medium would prevent the flare, but may well
cause a shadowy area at small apertures.

I would pass it up.

Colin D.

--
Posted via a free Usenet account from http://www.teranews.com

Paul Furman writes:

What is the effect of a scratch on the rear element of a lens?

Reduced contrast and resolution, at the very least.

The black-out technique only works at aperture planes. Otherwise you will
get an out-of-focus image of the flaw on your photo.

At small apertures it will be visible if blacked out. I've tried it.

Paul Furman wrote:

What is the effect of a scratch on the rear element of a lens? I'm
looking at a used lens, fast wide angle. I know a mark on the front
element can induce flare, not sure if the rear element is more or less
critical: http://i8.ebayimg.com/02/i/000/d3/24/887f_3.JPG


AVOID!

This is the worst possible place to have a scratch. You can get away
with small scratches on the front element, even eliminate their effect
by filling them in with black ink.

But scratches on the rear element are a different matter. Don't buy
the lens, regardless of how cheap it may appear. It will be an
expensive mistake, at any price.

On Jan 19, 1:58 pm, Paul Furman wrote:
What is the effect of a scratch on the rear element of a lens? I'm
looking at a used lens, fast wide angle. I know a mark on the front
element can induce flare, not sure if the rear element is more or less
critical:http://i8.ebayimg.com/02/i/000/d3/24/887f_3.JPG


If the price is right, less than 1/2 the lens in good condition and if
you can't find the lens in better condition at a similar price
elsewhere, I'd go for it. I bought a 50mm Summicron for my Leica M2
with several fungus marks on the back element, $75 so I couldn't
refuse. This lens was my sharpest 35mm lens of all time, just
incredible. But I don't shoot 50 on 35 that much so I sold it to a
friend for $100. We live in different states now but I see him every
once in a while and after 10 years he still tells me how great the
lens is. It is a gamble but if the price is right, go for it, may
surprise you. Use a wax pen to fill in the scratch after you clean
the rear element.

Tom

On 2008-01-19 13:58:00 -0500, Paul Furman said:

What is the effect of a scratch on the rear element of a lens? I'm
looking at a used lens, fast wide angle. I know a mark on the front
element can induce flare, not sure if the rear element is more or less
critical: http://i8.ebayimg.com/02/i/000/d3/24/887f_3.JPG

Other problems here as well indicating a somewhat abused lens. The
some of the mounting lugs seem to have "excessive" wear as well.
Wouldn' touch this one.
--
jen ... not.. home...//// yahoo... com

On Mon, 21 Jan 2008 10:13:47 -0500, "Rita Berkowitz"
wrote:
: Joseph Meehan wrote:
:
: I would expect a very large discount or a return option. Note I
: don't know how you would get a sure return option on eBay. Chances
: are good that you might be able to black it out with a fine felt tip
: marker and end up with a nearly 100% functioning lens, but then ......
:
: That's an eBay hosting pic and he doesn't have the actual lens in hand.
: Optically it is scrap. I would give the seller $15 for it and strip it
: down for parts.

Parts? What parts? Are you up for swapping out optical elements in an
expensive lens? Or do you just mean set screws, etc.? ($15 sounds like a lot
for a couple of set screws.)

Bob

I had a very evident fuzzy spot on some of my digital images which I
attributed to dust on the sensor of my D200, but cleaning it did not help. I
was going crazy until I noticed a small grease spot on the rear element of
my Sigma 10-20. Cleaning that did the trick.

To be fair, it was only noticeable at small apertures, and the design of the
lens (wide zoom) might have something to do with it, but it certainly
surprised me to find that something on the exit pupil was so significant.

Toby
"Paul Furman" schrieb im Newsbeitrag
et...
What is the effect of a scratch on the rear element of a lens? I'm looking
at a used lens, fast wide angle. I know a mark on the front element can
induce flare, not sure if the rear element is more or less critical:
http://i8.ebayimg.com/02/i/000/d3/24/887f_3.JPG