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milky glass, any cure?
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PostPosted: Thu Jun 27, 2013 12:07 pm    Post subject: milky glass, any cure? Reply with quote
recently I was a bit unlucky, both Canon LTM 1.8/50 and 3.5/100 I bought have an inner glass that is 'milky'
now I never was sure what makes a glass being milky and if there is any way to repair it.
anyway trying to clean them didn't make any change, and I much suppose that the fault is damaged coatings.

my question:
does milky glass generally mean damaged coating?
is there any way to tackle this problem, and if so, how?

there just was another thread about removing coating ( http://forum.mflenses.com/coating-removal-t59684.html#1326291 ) where I just asked how best to remove coating and how much sense it would make

thank you for any advice, andreas


PostPosted: Thu Jun 27, 2013 12:36 pm    Post subject: Reply with quote
I have the same issue with some lenses, it seems some kind of oxidation of the lens surfaces and I fear only repolishing would be able to remove that.

Tried many things, acids, lyes, but nothing worked for me.


PostPosted: Thu Jun 27, 2013 12:38 pm    Post subject: Reply with quote
Could it be a case of lens separation, where the canadian balsam which was used to glue the lens elements together is coming apart? If so, removing the coating won't help.


PostPosted: Thu Jun 27, 2013 1:25 pm    Post subject: Reply with quote
kds315* wrote:
I have the same issue with some lenses, it seems some kind of oxidation of the lens surfaces and I fear only repolishing would be able to remove that.

Tried many things, acids, lyes, but nothing worked for me.


thank you for your answer Klaus!
hm..this coming from you, someone who is so much experienced and as you said tried many things..is not very encouraging. Somewhere I had read the recommendation of using "Brasso' metal polisher. I did not find any "Brasso" locally where I am at right now, tried some other non abrasive metal polisher but without any success.
Guardian, in the other thread, mentions ammonium bifluoride. Have you tried?

Pontus wrote:
Could it be a case of lens separation, where the canadian balsam which was used to glue the lens elements together is coming apart? If so, removing the coating won't help.


yep, separation is the 'other' for me so far unrepairable fault. I am pretty sure that it's single elements that are effected in the mentioned Canon LTMs and unlike with separation or cementing faults I still have not given up hopes for a 'cure' of a 'milky' single lens element.

hope much that 'we' will get more suggestions, or possibly report of experience using ammonium bifluoride,
cheers, andreas


PostPosted: Thu Jun 27, 2013 2:34 pm    Post subject: Reply with quote
I have had a few cases of this.
I used this -

http://www.mothers.com/02_products/05100-05101.html

It has worked in at least a couple of cases.

It will remove the coating, if there is any left to remove, and with enough rubbing (plenty of rubbing) it can reduce the milkiness or remove most of it. I have even used it with a Dremel polishing wheel when I got bored of hand polishing.

Of course, this is not good for the lens shape, as it is not proper even polishing, but it can possibly make an unusable lens usable, though certainly not as good as new.


PostPosted: Thu Jun 27, 2013 6:00 pm    Post subject: Re: milky glass, any cure? Reply with quote
kuuan wrote:
recently I was a bit unlucky, both Canon LTM 1.8/50 and 3.5/100 I bought have an inner glass that is 'milky'
now I never was sure what makes a glass being milky and if there is any way to repair it.
anyway trying to clean them didn't make any change, and I much suppose that the fault is damaged coatings.

my question:
does milky glass generally mean damaged coating?
is there any way to tackle this problem, and if so, how?

there just was another thread about removing coating ( http://forum.mflenses.com/coating-removal-t59684.html#1326291 ) where I just asked how best to remove coating and how much sense it would make

thank you for any advice, andreas


It is very common to all Canon LTM lenses of those era.
(Mostly the surface of element facing to the aperture mechanism)

Just disassemble them, and clean them with micro-cloth.

However it will/may return to your lens again. very common.

Canon admitted that their choice of glass material had a problem.


PostPosted: Sun Jun 30, 2013 9:57 am    Post subject: Reply with quote
luisalegria wrote:
I have had a few cases of this.
I used this -

http://www.mothers.com/02_products/05100-05101.html

It has worked in at least a couple of cases.

It will remove the coating, if there is any left to remove, and with enough rubbing (plenty of rubbing) it can reduce the milkiness or remove most of it. I have even used it with a Dremel polishing wheel when I got bored of hand polishing.

Of course, this is not good for the lens shape, as it is not proper even polishing, but it can possibly make an unusable lens usable, though certainly not as good as new.


thank's Luis!
I had tried one metal polisher but it had not worked, I shall try some other product more, will look for a specially one for polishing aluminum wheels.
regards, andreas


PostPosted: Sun Jun 30, 2013 9:59 am    Post subject: Re: milky glass, any cure? Reply with quote
koji wrote:
kuuan wrote:
recently I was a bit unlucky, both Canon LTM 1.8/50 and 3.5/100 I bought have an inner glass that is 'milky'
now I never was sure what makes a glass being milky and if there is any way to repair it.
anyway trying to clean them didn't make any change, and I much suppose that the fault is damaged coatings.

my question:
does milky glass generally mean damaged coating?
is there any way to tackle this problem, and if so, how?

there just was another thread about removing coating ( http://forum.mflenses.com/coating-removal-t59684.html#1326291 ) where I just asked how best to remove coating and how much sense it would make

thank you for any advice, andreas


It is very common to all Canon LTM lenses of those era.
(Mostly the surface of element facing to the aperture mechanism)

Just disassemble them, and clean them with micro-cloth.

However it will/may return to your lens again. very common.

Canon admitted that their choice of glass material had a problem.


yes, I have figured that this is very common for these lenses, this is why I had decided to mention the lenses in question, and it's exactly the element facing the aperture!

oh, only micro cloth? certainly should try that too!
thank you for your input, regards, andreas


PostPosted: Sun Jun 30, 2013 10:01 am    Post subject: Reply with quote
Seeing what heavily damaged coating 'can' do to lens performance I still wonder if taking off coating could improve the lens at all. Anybody with experience, Luis, Koji?


PostPosted: Sun Jul 21, 2013 3:44 pm    Post subject: Reply with quote
kuuan wrote:
Seeing what heavily damaged coating 'can' do to lens performance I still wonder if taking off coating could improve the lens at all. Anybody with experience, Luis, Koji?


I haven´t tested this up to now.
But a partly mat coating could stray the light, which would be very bad.
Only some "shades" on the coating will probably cause no real problem, so lens uncoating is more harmful than helpful.

Canon LTM lenses have some collector value, I do not recommend such a harmful modification for such lenses. Hope simple cleaning could help enough.

Uncoated lenses have less light transmission, but this is the smallest of the problems. More stray light and reflections are the bigger problem.


PostPosted: Tue Sep 10, 2013 8:51 pm    Post subject: Reply with quote
Don't know whether this may be of interest:

http://www.marcocavina.com/articoli_fotografici/Zeiss_Contarex_55mm_1,4_Planar_recovery/00_pag.htm

Stefano


PostPosted: Tue Sep 10, 2013 9:29 pm    Post subject: Reply with quote
kuuan wrote:
luisalegria wrote:
I have had a few cases of this.
I used this -

http://www.mothers.com/02_products/05100-05101.html

It has worked in at least a couple of cases.

It will remove the coating, if there is any left to remove, and with enough rubbing (plenty of rubbing) it can reduce the milkiness or remove most of it. I have even used it with a Dremel polishing wheel when I got bored of hand polishing.

Of course, this is not good for the lens shape, as it is not proper even polishing, but it can possibly make an unusable lens usable, though certainly not as good as new.


thank's Luis!
I had tried one metal polisher but it had not worked, I shall try some other product more, will look for a specially one for polishing aluminum wheels.
regards, andreas


Autosol is probably the best alloy polish, it's excellent on chrome and metals and doesn't leave visible scratches, but have not tried it on glass.


PostPosted: Tue Sep 10, 2013 9:51 pm    Post subject: Reply with quote
Smac Brilla Acciaio!...hahaha, great Marco! Very Happy


PostPosted: Mon Oct 14, 2013 9:17 pm    Post subject: Reply with quote
Good grief! I would never have tried that, thinking the coating would be destroyed.
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