Lense scratches and affects

[Misty]

Hi I am new to enlarging and printing and understanding how things work in regards to this particular photographic process I have D2 enlarger with a 135mm lens which is scrachted and when I run my finger nail over the scratches lightly they do catch. I was wondering technically what scratches do to the lens in relation to producing a good image. Does the light fracture wrong or is cut into different directions causing problem areas in the printed image. Also, what do scracthes cause in addition to smudges on the final print...does it mess up the image grain pattern.....or what?
Thanks

[Kevin M Bourque]

I've always been amazed at how little a scratch really matters. I had an old Commercial Ektar with a nasty divot...darned if I could tell.

Much worse is a large number of fine scratches, which reduce contrast and introduce flare.

On the othe hand, enlarging lenses are giong cheap these days. You should be able to get a nice one off eBay for under $75 if you're patient.

[Leonard Evens]

Single scratches or even a few such scratches will usually not have a dramatic effect on the image. Such scratches scatter a bit more light than would normally be scattered. Scattered light produces what is called flare and decreased contrast in the image. If you can't see any effect in the image, then it is probably not important.

[John Layton]

I've never tried this - but have heard that if a scratch does introduce unwanted flare, this can be remedied without otherwise adversely affecting image quality by rubbing some water based black ink into the scratch - then cleaning the surrounding surface. Makes sense, but maybe someone else who has actually tried this can comment further.

[Nick Morris]

Hello.

I have a taking lens that came with my first 8x10. It is a mess, with scratches, a chip out of the rear element, separation. However, it can do a very good job producing negatives for B&W contact printing. I have another taking lens with a chip in the rear glass of the front lens. I put some varnish in the chip. I'm also told that black paint will work to reduce light being scattered by the chip, or by a scratch. The scattering of the light passing through the lens is supposed to reduce contrast and sharpness. I'm sure the degree of degradation depends on the severity of the flaws.

With nothing to really base it on, I would think that the degradation would be more of a problem with an enlarging lens. If you can borrow a good lens from someone, and compare the results by making comparative prints, you would know if the scratch is a problem. I think it can very hard to judge without making the comparison. A print can look good, until it is compared with a better print.

[Ernest Purdum]

A scratch filled with black ink, like John Layton mentions, has no optical effect except blocking light. It would take a really enormous scratch to be big enough to have any significant effect. The tricky part, of course, is filling the scratch without smearng up the rest of the lens surface. Do I know how? Nope.

[Ted Harris]

Misty,

You have to test it. Generally speaking one or two scratches are not likely to affect lens performance but it all depends on their orientation and placement.

[Paul Fitzgerald]

Misty,

"I have D2 enlarger with a 135mm lens which is scrachted and when I run my finger nail over the scratches lightly they do catch."

Bingo, start looking for another lens. Those are not cleaning marks, they will have a negative effect. Rodenstock, S.K., Nikon, Computar DL are all fine lenses and going fairly cheap at ebay.

Good luck with it.

[John D Gerndt]

A fingerprint is more of an issue than a scratch. Clean the lens and use it. You can start looking for a bargin in even beter shape according to your own time and price limitations. For price/performance value a Kodak 162mm can be found for under $50 and will do just peachy but DO clean any lens as well as you can including unscrewing it and cleaning the inside surfaces. It is the foggy film of ages that does the real discervice to enalrging lenses. Aligning your enlarger is a big factor in sharpness too.

Welcome to the beautiful world of making your own prints! You are going to love the control and increased quality you can afford by doing you own work.

Cheers,