Cleaning Leica lenses? Leave it to the pros
Removing Internal haze and fungus starts with taking the lens apart!
What’s the best way to clean your own precious Leica lenses? As little and as infrequently as possible, using the gentlest possible methods, and only addressing the readily accessible surfaces, namely the front of the front element and the rear of the rear element. To euphemize the time-honored California expression, schmutz happens, and when it lands on your lens you may want to clean it off before you resume shooting. While Leica lenses aren’t any more likely to attract dust, dirt, grease, grime, fingerprints, etc. than other lenses, some Leica optics, notably early versions of the 50mm f/2 Leitz Summicron, have soft outer coatings that are very easy to damage, and many Leica lenses use soft internal coatings because they have better optical properties.
DIY lens cleaning suggestions
For starters, you must decide whether there’s enough dust or dirt on your lens to affect its imaging performance—if it’s just a few specks of dust you may want to keep shooting rather than attempting to clean the lens in the field. Most dust and dirt can be blown off with a bulb-type ear syringe of squeeze blower. Canned air is another option, but you run the risk of propellant striking the lens surface or driving dust into unexpected places unless you’re very careful. You can also use your breath but dry your mouth with a Kleenex beforehand to prevent spittle from landing on the lens. Believe it or not swishing with an alcohol-based mouthwash or downing a shot of booze before breathing on a lens will give your breath a little extra cleaning power. If you use a brush to remove dust, don’t use the lipstick style camel’s-hair brush furnished with many lens cleaning kits—buy a fine artist’s brush, like a sable brush with natural undyed bristles ($30-$50 depending on size) and make sure to store it in a clean container. The lens cleaner and lens tissue included in the typical lens cleaning kit are not recommended either.
Dealing with fingerprints or grease marks is a little more labor intensive, but its best to remove such contaminants as soon as you can because they can sometimes cause permanent damage to the lens surface. For example, while fingerprints are far less likely to affect image quality than a grease mark in the middle of the lens, they often contain acidic skin oils that can etch the fingerprint pattern into the surface if they remain on the lens too long. Liquids suitable for cleaning lenses include ethyl or isopropyl alcohol (70% is OK, 91% is better), ROR brand of residual oil remover, a product often used by pros for cleaning lenses, a 50%/50% mixture of sudsy ammonia and water, and Zeiss Lens Cleaner, readily available in stores like Walmart, which contains “distilled water, detergents, and preservatives” and is claimed to be suitable for cleaning all glass surfaces. Any of these liquids should be used only to moisten a clean applicator rather than being poured or sprayed directly onto the lens, which can cause liquid to seep around the edge of the lens or damage the lens identification ring.
Suitable applicators for moistening with the lens cleaning liquids mentioned above include genuine Q-Tips (not store brand swabs) that have been “pre-softened” by rolling the tip between your fingers, and strips or cloths cut from well worn, well washed discarded cotton, such as cotton briefs, tee shirts, etc. Lint free Kim Wipes made by Kimberly Clark are an excellent option. There are also Zeiss packets with premoistened one-time use wipes (see illustration). Avoid microfiber cloths which can damage soft coatings and new (unwashed) cotton, which contains natural oils.
Start by cleaning the affected area with the moistened applicator, and proceed with a circular motion until you reach the outer edges of the lens surface with a gentle touch and stop once the lens is clean. Resist the temptation to go over your work- you’re done. Please note that we not experts, and that anything you do on your own to clean your dirty lens is at your own risk. Finally, of course prevention is recommended too. Keep caps on your lenses when not in use, and consider mounting a high quality filter (such as a Leica, B&W, or Heliopan clear or UV filter) on your lens even while shooting—its effect on image quality is negligible, it’s a lot cheaper than replacing your front element, and your pristine lens will fetch a higher price if you ever decide to sell it.
Professional lens cleaning: a cost/ benefit analysis
The major deciding factors on whether to have you lens professionally cleaned to removed internal haze and fungus are simple and straightforward:
Is the problem serious enough to warrant spending at least 100 bucks to have the lens disassembled and cleaned? and
Are you going to use the lens or is it perched in a showcase as a collectible? A small amount haze or fungus at the edges of the lens is likely to have little effect on its image quality, and if the lens is stored in a cool dry place with good air circulation the problem is unlikely to get worse. If the lens is part of a showcase display and unlikely to be used for taking pictures, do yourself and your repair person a favor, save yourself the time and money, and don’t bother having it cleaned.
If the lens does have significant haze or fungus, especially in the central area where it’s likely to negatively impact its image quality, and you do intend to take pictures with it, it surely makes sense to have it professionally cleaned, but beware of the pitfalls. Most experienced pros use acceptable solvents to remove fungus and haze from the affected surfaces of internal elements, and in many cases, they can restore a lens to something resembling its original pristine glory. However, they can’t always remove all the contaminants, especially fungus or acidic haze that has eaten into the glass surface. And if the internal coatings are soft, they may be damaged or even entirely removed by the cleaning process. Yes, you can still shoot sharp pictures with your beloved Summicron that’s missing the coating on one if its internal elements, but it will have a greater tendency to flare in backlit and other high flare situations.
In short, professional lens cleaning, even by the most adept and experienced repair people is not guaranteed to be completely successful. If you want to have your lens cleaned, find a reputable repair shop with a good reputation, and then maybe cross your fingers.