Feasibility of DIY front element scratch removal.

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schmoozit

Schmoozit good...
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I have an uncoated 50/2 Summar, and though there is a slight haze, the biggest "problem" is the front element surface with many scratches. Since it is in fact uncoated, I wondered how difficult it would be to try to remove them, hopefully by some sort of polishing. I swear I've heard someone say you could do it with toothepaste, but I'm thinking there just might be a better alternative; or should I break out the Crest or Colgate? Flouride protected? Minty fresh?

I've succesfully relubed my 85/1.9 Canon, as well as the Summar, and I'll get a repair post up within a day or two, hopefully.
 
Personally, I've not tried it - my gut tells me it would be a very bad idea indeed. Focal Point in Colorado is one of the services which can repolish lens elements - the cost may be high, though - I don't know. Toothpaste? No way, abrasive. Yikes!

Are you sure the scratches are causing problems? How many scratches are we talking about here? I've got some very old camera books that recommend using very minute quantities of black paint to fill in scratches.

WHAT? That sounds horrible! But I read on - it actually makes sense. You see, the surface of the lens as a whole is angled to focus light in one place, and it continues to do so even when scratched. The problem is that the side of the microscopic 'trough' caused by the scratch are NOT pointing where the surface of the lens points - they instead point off in random directions and bounce light around like crazy, causing flare and loss of contrast. When filled with an absorbant color (black), they cease to pass light. Occluded yes, but no longer radiating in unplanned ways. The authors report that it would take a huge amount of scratches to cause any appreciable loss of light if the scratches are filled in this manner. Worth a try perhaps? I could dig out the books and quote to you if you like, I just have to find them again.

Also - at least one online author reports (I think it is Dante Stella, if memory serves) reports that the softness of the Summar is the entire charm of the lens - it is not sharp and that's why he likes it and others hate it. Of course, he also attributes the "Leice glow" to this - some Leica fans get irate when reading that their characteristic signature is caused by, err, errors.

Personally, I'd love to have a Summar, scratched or not.

Best Regards,

Bill Mattocks
 
Yeah, now I remember hearing about filling the scratches in. It makes sense to me, and maybe I'll try with another lens. The "problem" with the Summar, and the quotes are to indicate that the lens is still usable and gives me images that are pleasing, is that there are so many scratches that it is effectively like a haze. I've not had opportunity to test yet, but I'd say that it probably costs me around two stops of light.

I'm just curious, and it sorta sounds like fun to give something a try. The best alternative, I'm pretty sure, is to find one without a scratched front element, but that's destroyed otherwise, get a deal and swap it out with my current one. Then I can try some toothpaste, or other procedure, just for kicks, and no real worries.
 
Jeweler's cloth

Jeweler's cloth

If you're keen on polishing, get a jeweler's cloth, the kind that watch dealers use when polishing off fine scratches on watch faces and bracelets. Search the horological websites to find such dealers.

Beware that polishing means rubbing off surrounding glass to level the scratch. It can theoretically change the optical properties of the lens ever so slightly. But then, it's a cheap lens, so go ahead.




schmoozit said:
I have an uncoated 50/2 Summar, and though there is a slight haze, the biggest "problem" is the front element surface with many scratches. Since it is in fact uncoated, I wondered how difficult it would be to try to remove them, hopefully by some sort of polishing. I swear I've heard someone say you could do it with toothepaste, but I'm thinking there just might be a better alternative; or should I break out the Crest or Colgate? Flouride protected? Minty fresh?

I've succesfully relubed my 85/1.9 Canon, as well as the Summar, and I'll get a repair post up within a day or two, hopefully.
Click to expand...
 
waileong said:
Beware that polishing means rubbing off surrounding glass to level the scratch. It can theoretically change the optical properties of the lens ever so slightly. But then, it's a cheap lens, so go ahead.
Click to expand...
This is very correct. Also, this is exactly why toothpaste will more than likely not work. As far as I know, it has no abrasive qualities.

Just for reference, here is a good article on removing scratches (from any surface). It is on a detailing forum and is dealing specifically with automitive paint, but the general idea is exactly the same.

http://meguiarsonline.com/forums/showthread.php?s=&threadid=7228
 
Well, yes, the whole idea would be to rub off surrounding glass and level the scratches; I understand that. I'm just looking for ways to do it. The toothpaste thing sounds a little hokey, but then it is a nice polish for metals/jewelry. I never got the sense that it was actually rubbing off fine amounts of my wedding band, however. Maybe I'll target a scratch on my band and see if it takes it out.

Thanks for the ideas so far. I feel that there is something better out there, but just don't know what it is. I'm not in a major hurry. The jewelers cloth is a great tip, even if i don't ever use it on a lens. I didn't know they existed. Pretty cool.
 
Toothpaste does contain a mild abrasive called Dicalcium phosphate dihydrate. Since polishing is about producing smaller and smaller scratches on the surface of an object. You might want to find out what is the typical grit size used for polishing lenses. Hobbyists still polish their own telescope objectives. Try finding what they use through google.
 
Without a proper glass-polishing apparatus I don't see how you would be able to do it exactly evenly all over the surface. Right now you've got a lens that's low in contrast and prone to flare. After you polish it you may well have one that's just unsharp. To me it wouldn't be worth the time and effort, but as someone said, it's a cheap lens.
 
Nick R. said:
Toothpaste does contain a mild abrasive called Dicalcium phosphate dihydrate. Since polishing is about producing smaller and smaller scratches on the surface of an object. You might want to find out what is the typical grit size used for polishing lenses. Hobbyists still polish their own telescope objectives. Try finding what they use through google.
Click to expand...

Is that called chalk? That's what I have heard is in toothpast. And yes, I have heard of using that, with the caviat that you are going to change the curvature of the lens. I remember reading it in a camera repair book. I have used it for removing scratches on wrist watch crystals, but never lenses.

Looks like Nick's suggestion might be a good one as to telescope hobbyists. There is a very knowledgable person (besides being an avid deep space photographer, he is a docent at an observatory) on the PP&I web site who uses the name Astroimager. He might be able to offer some insight on that.
 
FYI, See my series on refurbishing the front element on a early 'cron under "Repairs" section on this site.
Johne
 
johne said:
FYI, See my series on refurbishing the front element on a early 'cron under "Repairs" section on this site.
Johne
Click to expand...

I already did, and have contacted Arax about a possible servicing. They sent me a prompt email, and I'm keeping that possibility open. They said they'll charge me $30 a surface, with or without multi-coating. Sounds pretty darn reasonable.

Thanks to everyone, really. Excellent ideas here, and useful for many things, I think.
 
The two options presented so far:
- Colour in the scratches (i.e. such that they do not discurb the image
- Remove the material around the scratches (which is what posiching does).


There may be an other way:
Fill in the scratches with a transparent soft substance (plastic? glue? etc).
- The transparency will reduce the light scatering of the scratche
- provided the breaking index is not too far of the material of the lens.
- provided you get a good contact between filler and lens (clean very well).
- The softmess will allow to remove the excessige (sticking out) bits by polishing
If it is soft enough it will not atack the actual lens glass and hence not change the
properties.

I think this is the proceure carrglass uses to repair windschreens of cars.

mad_boy
 
Optical grease has the same refractive index as glass. I wonder if it could be rubbed into the scratches in such a way as to fill in the voids and not be left on the lens surface.
 
schmoozit said:
I have an uncoated 50/2 Summar, and though there is a slight haze, the biggest "problem" is the front element surface with many scratches. Since it is in fact uncoated, I wondered how difficult it would be to try to remove them, hopefully by some sort of polishing. I swear I've heard someone say you could do it with toothepaste, but I'm thinking there just might be a better alternative; or should I break out the Crest or Colgate? Flouride protected? Minty fresh?

I've succesfully relubed my 85/1.9 Canon, as well as the Summar, and I'll get a repair post up within a day or two, hopefully.
Click to expand...


My apologies for being slightly off topic ... but have you tried shooting with the lens? The Summar is full of abberations and the signature is rather unique, haze and scratches sometime contribute to the dreamy results.

My first copy of Summar has (almost) perfect glass, but I return it becasue the effect is not as pronounced. I end up getting one that, while rather unsightly, give me the look I'm aftering. If you like glowy, low contrast B&W or muted colour pictures, you may capitalise on the defects :) Here's one from a Summar with beat-up front element.

MP+Summar+Tech Pan @ 50 in Diafine 4+1
original.jpg
 
Regit: Thanks a lot for that. I may just keep this one as is and search for a less "dreamy" one in the future. I just souped some pics from Christmas and really like them. It's not that I was being put off from the results I've been getting, though I didn't think that they would be much less dreamy with a cleaner front element. Now, with what you say, maybe I was wrong. Hmm... I'd hate to have Arax ruin my junky lens ;)

Much appreciated. Happy New Year!

P.S. Maybe I'm wrong, but I think I've seen that face before. Do you shoot with Fuji RFs as well?
 
schmoozit said:
Regit: Thanks a lot for that. I may just keep this one as is and search for a less "dreamy" one in the future. I just souped some pics from Christmas and really like them. It's not that I was being put off from the results I've been getting, though I didn't think that they would be much less dreamy with a cleaner front element. Now, with what you say, maybe I was wrong. Hmm... I'd hate to have Arax ruin my junky lens ;)

Much appreciated. Happy New Year!

P.S. Maybe I'm wrong, but I think I've seen that face before. Do you shoot with Fuji RFs as well?
Click to expand...

I've heard a quote from somewhere, along the line ... "there's perfection in imperfection", and I guess this applies very well to the Summar :) Enjoy the lens as it is and a Happy New Year to you too!!!

And no, I think you got the wrong face. I've never use a Fuji RF... yet...
 
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