DYI lens polishing? Anyone?

Monochrom

Monochrom

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Hi i bought this elmar 3.5 cm f3.5 lens for a few bucks.

ALthough inexpensive it has the front element with enough scratches to make the images glow.

Has anybody made some DIY polish project?
 
If you take off enough to take out the scratches, you will alter the optical formula of the lens. Do you have the tools and experience to readjust the lens?
 
I know, i can readjust the lens i´ve made this with re polished lenses and other flawed glasses, not a difficult task.


But i´d love to have some advice and tips on how to polish.

THX
 
I haven't done it, but were I to undertake such a project, I would probably approach it thus:

- Make a cast of the front element (plaster? hard urethane? need to research materials).
- Apply polishing compound to the cast and place the damaged element on top. This should preserve the curvature of the element as long as even pressure is applied.
- Use a suction cup on a shaft and spin the element in the cast. If you want to be very precise about it, you would need to rig a brace over the cast to support the spinning shaft and prevent it from moving laterally.
- Move to progressively finer compounds until the element is polished.

The selection of the starting compound would depend on the extent of the damage (depth of scratches). You will, of course, lose any coating on the front element, and even with these precautions, you are likely to alter the optical formula slightly; whether this has an effect on photographs is a different question.

I've got a hideously scratched up I-50 that may serve to test this process at some point, but it's not on the high priority list right now.
 
Excellent idea!!!

I do use poliurethane and sylicon resins for making other thngs.

I will make an stand in which to sit the front element and then with the cast of the front part i will polish.

The lens is too damaged to make good pictures it´s uncoated and very small.

Marks aren´t deep so i think with your idea i´ll have better chances.

I´ll make some shots BEFORE and AFTER.

😎
 
If you have access to a vacuum chamber, you could try to evaporate some MgF2 with a high current arc, and have it condense on the newly polished surface.

That would be awesome.
 
There is an excellent and famous repairman located in Southern France who repolishes lenses for a modest price using the proper tools preserving the optical curvature radius. If you intend to use the Elmar for taking pictures, sending it to him (depending on where you live) might be the best option.

http://www.nicorep.fr/index_uk.htm

http://www.nicorep.fr/uk/polissage.htm

The material for repolishing lenses is ceryum oxyde powder in a polishing compound.

The front element must be removed ; you don't want the polishing compound to get everywhere inside the lens assembly.
 
02Pilot said:
I haven't done it, but were I to undertake such a project, I would probably approach it thus:

- Make a cast of the front element (plaster? hard urethane? need to research materials).
- Apply polishing compound to the cast and place the damaged element on top. This should preserve the curvature of the element as long as even pressure is applied.
- Use a suction cup on a shaft and spin the element in the cast. If you want to be very precise about it, you would need to rig a brace over the cast to support the spinning shaft and prevent it from moving laterally.
- Move to progressively finer compounds until the element is polished.

The selection of the starting compound would depend on the extent of the damage (depth of scratches). You will, of course, lose any coating on the front element, and even with these precautions, you are likely to alter the optical formula slightly; whether this has an effect on photographs is a different question.

I've got a hideously scratched up I-50 that may serve to test this process at some point, but it's not on the high priority list right now.
Click to expand...

... that all sounds very reasonable ... I do know that 'Jewellers' Rouge' is just iron-oxide (rust) and is used as an abrasive polish
 
Thanks for the advise....but i want to do it myself.

Today i´ll make the cast on sylicon resin.

The vacuum chamber with high current arc and delirium vapors would be in deed awesome..😀 I´ll have to do with a more modest method thou 😀

I´ll try to post some pics of the process, now i have a rx100 that´s terrific for this things.

😉
 
I'm wondering if filling in scratches with optical cement would be better than grinding down to the bottom of the grooves. Perhaps a combination of the two would work. You'd have to test your polish on the cement though to make sure it responds well. Just an idea.
 
Hi, yrsterday i started making the test on kaputt glass...then i sat polishing during 5 hours.

The lens scratches easily but polishes...very slowly.

I think i´ll finish it in the evening.

I got rid of almost 80% of scratches...but you know...success means a fair IQ.

Hope tommorrow 20 i´ll be able to shoot some pics. Cross fingers 🙄
 
It is a good idea, some weeks ago i had to re cement an m3 prism...the "technician" used loctite on another one...so i used a UV cement that left the prism very good. I put a drop of this cement over a loup but never ever cured, not even under hard UV light. This cement is awesome but must be so thin as a layer `tween two glasses to cure perfectly.

So over the scratched lens "should" work but i´m unable to cure it that way.

CNNY said:
I'm wondering if filling in scratches with optical cement would be better than grinding down to the bottom of the grooves. Perhaps a combination of the two would work. You'd have to test your polish on the cement though to make sure it responds well. Just an idea.
Click to expand...
 
Monochrom said:
so i used a UV cement that left the prism very good. I put a drop of this cement over a loup but never ever cured, not even under hard UV light.
Click to expand...

Hard UV will not cure that cement. You need UV-A - and if you glue glass to glass, you'd be better off with a deep blue LED, as glass will block the UV spectrum from a low pressure discharge lamp.
 
I used to polish optical prism cut from single-crystalline silicon wafer-material to be used as carrier for electroless deposited metal films (platinum). The diluted HF used in the metal film deposition process left some pit corrosion in the surfaces and from time to time the surface had to be polished using a commercial diamond paste, took about three complete days to get the surface free of pits. Polishing a soft lens surface must be a difficult task, you are brave! 🙂

On a side note, did you disassemble that Elmar and if yes, how? I have one with a stiff aperture and would be glad about some tips to reach the aperture mechanism for a cleaning and re-lube.
 
Sorry, perhaps I have missed it, but, what did you end up using as a polishing agent? Slow sounds tedious, but much, much better to me than too fast. Slow should mean a more gradual removal of material. Hope it works out for you, this sort of stuff is fascinating to me, personally.
Cheers
Brett
 
I confess I've once polished out the blemished front and rear surfaces of a Xenon 50 f/1.5 with nothing but toothpaste and a damp lint-free cloth.
 
I have seen a video on YouTube I believe that showed the Kodak factory grinding lenses. If I recall, it took the machines quite a long time to do an element. I would suspect that without some type of mechanical advantage speeding up the process, you are going to be grinding a long time with just your hands.

Also, look up how astronomers grind mirrors for their telescopes.
 
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