Scratch on lens...

Dorothy Blum Cooper · May 18, 2010

Been a while since I've posted on Apug. Wanted to hear what you thought of a slight scratch on a lens I recently purchased. The lens is an older/vintage, 480mm Rodenstock APO Ronar.

Lens has what appears to be a very slight surface scratch (maybe 1/4" at that). Not deep, but it's there on the surface. Lens was a great price and will allow me to experiment before making the bigger investment (should I choose to ever replace this lens).

I've done some reading on 'scratched lenses' and thus far, deduce that I should leave it be. Says I can actually do more harm to the lens attempting to buff, polish or attempt repair to the glass.

What say you?

Pupfish · May 18, 2010

In controlled or muted lighting it's unlikely to affect your images. Shooting into the sun or any specular light source (like flash) it could result in flare.

It's sometimes recommended to fill such a scratch with India Ink.

Mainecoonmaniac · May 18, 2010

Why don't you do some shooting with it as a test. Chances are, the scratch doesn't affect the image quality. Just leave it be. Buffing it will probably do more damage to the lens because you might rub off the coating on the lens. It's like that pimple on prom night. It perceived bigger than it really is

domaz · May 18, 2010

It's not going to effect anything. If you don't believe me look at this lens test:
http://kurtmunger.com/dirty_lens_articleid35.html

If you are taking pictures into the sun ya, maybe you will notice some contrast loss. But unlikely.

fschifano · May 18, 2010

Use a lens hood if you think that flare will be a problem; but then you should be using one anyway. Don't worry about it.

Dorothy Blum Cooper · May 18, 2010

Excellent advice and information...you've helped answer several questions I had. As always...thank you!

ac12 · May 18, 2010

he he
It is probably like the gunk that seems to collect on my glasses.
I don't notice it until I look AT my glasses.

Galah · May 18, 2010

Dorothy Blum Cooper said:
...What say you?

Check out this link:

http://www.pentaxforums.com/forums/pentax-slr-lens-discussion/40521-dead-lens-club.html

steven_e007 · May 19, 2010

According to the excellent manual by Arthur Cox, 'Photographic Optics', the fix for a scratch is to fill it with an opaque varnish (or black paint).

I suppose these days you could use acrylic paint as, being water based, you could easily remove it and try again if you messed it up.

The reason for doing this is because a scratch will disperse light at that point, causing flare...

BUT! Little scratch, very little flare, methinks

Bottom line, can you see a problem with flare when you use the lens? Is it actually causing a problem? I really doubt it...

Best policy is probably not to do anything at all unless you know the scratch is causing an issue.

Any attempt to polish or buff the lens will scrap it, I'm sure.

Mike Kennedy · May 19, 2010

I was given an old Tamron SP lens with a gouge across the front element.Filled in the rut with Indian ink,let it dry,and cleaned with a microfiber cloth.
Shot a test roll with the sun just out of the frame.No flare!Keep in mind that this lens looked like it was "Keyed" and what I did was a radical fix with nothing to loose.
Give your glass,with hood, a try and see how it performs.My solution is a last resort.

Mike

R gould · May 19, 2010

Would'nt worry about it,I have a 80/200 zoom, got o scratch on the front element,using a lens hood I can see no detremint ,Richard

sandermarijn · May 19, 2010

This lens came with a chip out of the front element, as well as some cleaning marks. I painted the chip with a water-resistant black marker. All is well

I think the consensus is that the rear element matters, not the front.

Whiteymorange · May 19, 2010

steven_e007 said:
I suppose these days you could use acrylic paint as, being water based, you could easily remove it and try again if you messed it up.

Any attempt to polish or buff the lens will scrap it, I'm sure.

Excellent advice, with one caveat: Water based is not the same as water soluable. Acrylic paint is liquid plastic and in not easily removed after drying. I have used permanent marker, which will wipe away with alcohol.

Dorothy Blum Cooper · May 19, 2010

Thank you guys again...some great advice in here. Will let you know how it turns out (test shot). Hoping I won't need a fix, but will heed the suggestions.

steven_e007 · May 20, 2010

Whiteymorange said:
Excellent advice, with one caveat: Water based is not the same as water soluable. Acrylic paint is liquid plastic and in not easily removed after drying. I have used permanent marker, which will wipe away with alcohol.

Yes, quite so. I was thinking more that you could repeat the operation if you 'missed' the scratch and splodged paint in the wrong place - but yes, once it is dry, acrylic is fairly permanent. That is ideally want you ant, otherwise it would come off when you cleaned the lens, but certainly as a test, something temporary would be better. Personally I think a few shots with scratch covered and a few shots without would prove if there is any point doing a more permanent repair... and my hunch is there won't be.

domaz · May 20, 2010

Whiteymorange said:
Excellent advice, with one caveat: Water based is not the same as water soluable. Acrylic paint is liquid plastic and in not easily removed after drying. I have used permanent marker, which will wipe away with alcohol.

Isn't permanent marker a mild solvent that could strip away coatings. It sure smells like a solvent.

Scratch on lens...

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