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Likaleica1
Tinkerer
Username: Likaleica1
Post Number: 4
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 13, 2007 - 02:26 am: | 
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Surprisngly hard to find sensible advice on cleaning lens optics which are simply grimy from years of use. I mainly have uncoated lenses from pre-war cameras. Can anyone advise how best to clean these, as well as later coated lenses please ?
See my Leica copies website www.likaleica.com |
Dgillette4
Tinkerer
Username: Dgillette4
Post Number: 94
Registered: 04-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 13, 2007 - 04:01 pm: |
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My way is to blow off and take a camel hair brush and gently clean. Then put some lense cleaner on a piece of tissue, gently wiping. (do not pour on lense). This goes for coated and uncoated. Don |
Commando303
Tinkerer
Username: Commando303
Post Number: 3
Registered: 10-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 13, 2007 - 10:37 pm: |
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I'd just use a little window-cleaner (with ammonia) and wipe with a Kleenex. Of course, take it easy, and, before doing any of this, blow off as much dust/dirt as you can (either by mouth, or using a blower-brush). Beware that small particle can sometimes scratch lens glass or lens coating; also, some coatings, especially on older lenses, are especially soft, and so prone to being scratched. |
Rj_
Tinkerer
Username: Rj_
Post Number: 51
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 15, 2007 - 03:11 pm: |
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Hi there,
Typing in 'lens cleaning' in google, seems to bring up countless advertisements for products from various sellers instead of information. Guess it's true then.
Just to add a little to the above, here's one method which I use. A work surface with a plastic mat to wipe off the debris with a specular light source (halogen) works better for me.
The general principle remains the same as the above recommendations - namely - to remove adherent surface particulate matter without turning particulate debris into an abrasive against the lens, by dragging particles across the surface of the lenses. This step enables the surface of the lens to be inspected, following which a decision for further treatment can be decided.
In the initial step, some restorers prefer a blower brush, although a vacuum dust remover with a dust nozzle also can be used. It may be better to avoid contact with an unknown matter on the lens with a blower brush in case of transfer of materials such as fungal spores to the tips of the blower brush or vacuum.
Once the dust is removed, by far the most effective contact cleaning fibre is microfibre, due to its ability to retain particulate matter and trap this in its fibres, working it into the fibrecloth away from the lens, so that the lens is not scratched.
If it makes any sense, this is a step I tend to defer until the lens is 'cleaned' in the manner described below. Perhaps this is borne out of my concern for transferrable contaminates on the microfibre for grime on old lens can contain spore material.
After the contactless dust blower/vacuum stage, a disposable lens tissue method can be employed. A square of lens tissue is folded along its diagonal, and then folded loosely in two more folds to form a wad extending from a few millimetres to a centimetre. The length of the wad determines the degree of pressure applied in cleaning the lens surface.
The wad can be dipped in a bottle of uncapped industrial alcohol (isopropanol) so that it is moist or dabbed rather than saturated. The larger traditional chemistry bottles tend to be my preference: small 15ml bottle sizes tend to be upset easy and can spill when knocked gently, whereas the larger bottles tend to stand upright.
Holding the lens barrel in one hand with the aperture blades at full aperture, use a radial swabbing method from the centre of the lens surface to the circumference. It may be tempting to work in tangential strokes, however the radial method is carried out in a sequential manner from 12 o'clock to complete a full cycle methodically moving trace particles to the margin of the lens barrel. The swab may need to be reformed depending on how much dirt is produced, and the isopropanol should not be contacted directly with the lens tissue, but dropped onto the cleaning tissue. Complete with a final circumferential sweep with another lens swab.
Some classic lenses have front elements which are easily accessible, set within brass mounts which can be removed. It may not be necessary to proceed any further than this step, and a microfibre clean can be used after the initial cleaning stages.
If there is evidence of white spore colonies, either dried, crusted or in star shaped colonial formation, then the isopropanol stage may need to be further treated with Hydrogen Peroxide.
Hydrogen Peroxide in low concentrations, from 1% - 9% is used as an oxidising agent which finds its application in antisepsis as well as industrial cleaning. No more than a 5% solution is required for spore removal. In contact with brass barrels, the hydrogen peroxide would most certainly strip brass if left in contact long enough. Damage to plastic mounted lenses can also occur, however the time scale for a swab, moist in 5% hydrogen peroxide is generally insufficient to cause any damage to brass, metal barrels or plastic surfaces. The Hydrogen Peroxide, left exposed to air, rapidly becomes oxidised to a 'water' byproduct which can be wiped off. The same radial technique followed by a circumferential sweep with a moist swab kills off most fungal spores and prevents reoccurence, provided this stage is thorough. Once again, only disposable tissue is used, rather than microfibre due to the risk of spore transfer. Both alcohol and hydrogen peroxide in low concentration and for short contact durations show no signs of penentrating lens coatings. Some German lenses from the 1950's were (soft)-coated i.e. Plaubel Makina lenses. I've seen lenses with the coatings semi-stripped from the use of window detergent which does contain abrasives. Personally, I have no fondness for ammonia based cleaners due to its noxious byproduct although it has its advantage in being very easily obtainable.
Finally, the use of a microfibre, is also applied with a breathe on the lenscloth (not the lens) before wiping the lens in the same methodical manner.
For reference, a 50ml bottle of 5% Hydrogen Peroxide costs 0.40 Euro or £0.29 in Europe/England. Isopropyl alcohol from a chemist at around £0.99 (1.4 Euro) for a 50ml vial.
The designer cleaning products are often marketed with a tenfold mark-up in cost, and achieve nothing original. Perhaps I find these products rather exploitative of the general consumer's lack of foundation in chemistry: 'Pro-phot' which is marketed as the ultimate lenscleaner for aircraft windows, is particularly expensive and achieves nothing over and above the use of a Kentucky Fried Chicken freshen-up wipe at ten times the cost. The base of the lens tissue is also particularly heavy and prone to leave damage to lenses, partly because users of this convenience product have no appreciation of that wiping the surface dust with a Pro-phot acts as an abrasive.
The Opticlean 'chemical gel' spread is exceptional in its design - this is probably one of the few optical cleaning products which can be recommended despite its cost. It's major limitation seems to apply to the layer of gel 'fracturing' at the circumference of the lens where some of the gel may seep between the lens and barrel, thereby becoming trapped when tugged on removal.
I hope this helps clarify lens cleaning for you, or at least, demystify some of the principles behind one technique.
Kind regards,
RJ
This stage may need to be repeated for all the surfaces of the lens which is affected by the spore colonies.
After cleaning, store |
Rj_
Tinkerer
Username: Rj_
Post Number: 52
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 15, 2007 - 03:13 pm: |
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Ignore the last 3 lines....
Now all I need is someone to help me clean up the editor for the last post  |
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