"Cleaning Marks" on lens, OK?

I'm looking to buy a 50mm Distagon - a T* lens.

 

When I had a look at the lens from the rear into the light there were

a series of clear scratches across the full width of the front element.

 

On turning the lens around and looking at the front element you could

just see the scratches - they are not very thick or deep. Nevertheless

there are about 6 of them and they have made a visible impact on the

coating. The current owner is a very genuine guy and he didn't know

these scratches were there until I showed him.

 

Are these scratches going to cause an appreciable impact on image

quality? Are they going to be the sites from which the coating

deterioriates. Is it worth buying this lens?

 

thanks for your help

 

Regards

 

Mike

I doubt that marks on the front element will make any visible difference to the lens' performance. It might be worthwhile to use a hood with it just to counter any increased tendency to flare. I have used lenses with fungus and scratches with excellent results. It depends where the damage is and front element damage is just about the least serious.

I shoot with a 210mm lens on my M645 that has a large patch of separation, but I never see it in the images because it is on the edge of the lens and I typicaly shoot stopped down a bit from wide open. I doubt that these marks will cause futher damage unless you are careless with the lens and they will likely have no effect on images at all, especialy if you shoot with a hood.

 

I never worry about minor marks if the price is good, but then again, it is a personal choice so I would suggest that you listen to everyone's opinions and then make your own decision.

 

- Randy

Cleaning marks in the form of light scratches do affect image quality. If there are just five or six, it might not be a problem. If there are many, it can cause some flare in the central part of the image or a slight degradation of sharpness.

 

I would suggest shooting a roll of transparency film as a test.

It will probably have little to no effect. How are the other cosmetics? Since the glass does have scratches try to factor this into the cost of the lens. Glass w/ scratches does command a lower price on the market.

 

Don't forget to use the lens shade.

.

 

If you are aprehensive that randomly scatterd light passing through the scratch will contribute non-image forming light to the film, then you can fill the scratches with black india ink to cause them to not participate in the capture. The loss of speed due to less lens opening should be so insiginficant as to be unmeasurable. I often obtain scratched lenses for a tiny percentage of their true value, and black india ink completely negates any effect of even the worst surface scratches.

 

Let us know what you do.

 

Click!

 

Love and hugs,

 

Peter Blaise peterblaise@yahoo.com http://www.peterblaisephotography.com/

With a permission from the owner you may want to try to wipe a very small portion of the mark with a micro-fiber cloth to see if the scratch is indeed cleaning mark. If it can be wiped off from a small portion you can clean up the entire of it. Cleaning marks look like scratches but can be wiped off. Scratches are permenent and there is not much you can do to change it.

This same question was asked in the Medium Format Forum on October 25th with regard

to a TLR Rollei. Here is what I said a week ago:

 

There will be no degradation of the image from small scratches on the lens or even a

bubble in the glass during the lens-making process.

 

The only time this type of damage causes a problem is if it actually takes a chip out of the

lens and you get light refracting from the chip area. Usually this is easily fixed by using a

needle dipped into flat black paint and putting a dot of paint in the chip. This eliminates

the refraction and the dot is so far out of the focal plane it makes no impression on the

film.

 

Look for "fungus, foggy spots or spider web type growths" between the lens elements as

this can cause problems depending on how severe it appears.

 

----

 

Obviously one of the contributors above has said that even with fungus between the

elements he didn't have a problem. Severe fungus will cut light transmission.

Technically "anything" in the lightpath will cause image degradation but when talking

about scratches, they are so far out of focus that they will not be detectable, even with a

microscopic examination. The film itself is a more limiting factor than scratches on the

lens. As a percentage of the lens surface even several scratches wouldn't be measurable.

 

Don't worry about it; use this "problem" to your advantage to strike a good deal.

Sort of like buying a shovel with a spec of dirt; a lawnmower with a blade of grass under the deck; a surf board with a grain of sand on it; a beer can with a microdent; A Harley with a drop of oil somewhere on it; Buying D9 cat with a clump of gumball mud on it. These are MAJOR things that some folks consider as being a problem. :) In practice; whether some scratches really matter often is emotional; and less a real problem,.

Thanks everyone for your detailed responses. The marks were pretty clear and were definitely scratches rather than anything else - however caused.

 

The lens went for a fair chunk of money finally and I decided not to have a shot at it. I felt it was too much for the condition of the lens.

 

Regards

 

Mike

<p>I'm about to buy a medium format lens with cleaning marks on the rear element:<br /><br /><img src="http://lantosistvan.com/temp/cleaning-marks-jpg.jpg" alt="" width="415" height="360" /><br>

This will effect the final image or not? What do you think?</p>