lens cleaninggreenspun.com : LUSENET : Large format photography : One Thread
I'm sure this is going to reveal my compulsive side, but is there a method to clean pinpoint spots from a lens. I'm talking about the kind that you can see when you look through a lens, not at it. When you look through a lens towards a light source its as if there were a fine mist on the lens, not evenly distributed. Oh, the lens (a fuji 300c) produces great negatives so maybe I should be so concerned? Like I said I can get a little compulsive.
-- kevin kemner (firstname.lastname@example.org), December 18, 1999
I have the same experience with my canon 85mm lens, like a clear sky in a summer night when look through the lens. I've tried hard to remove them and hope I could get a perfect spotless surface but failed everytime and finally gave up. I don't believe anyone can claim his lens is perfectly spotless once the lens being cleaned by the usual way.
It doesn't seem to have any effect on image quality so I just let it be.
-- Aaron Rocky (email@example.com), December 18, 1999.
I asked the same question a while back and received some wonderful responses from several contributors. Go to the archived files at the bottom of this page under "lenses" and about half way through the section (190 items on file), you will see the responses under "Cleaning Smudges" to my question.
-- Michael Kadillak (firstname.lastname@example.org), December 18, 1999.
When lenses are assembled in a repair shop, the elements typically get bathed in something like spectrographic grade acetone. This is an extremely volatile solvent that attacks painted surfaces and can do other kinds of damage, most notably to one's kidneys, if inhaled to any great extent. It does, however, do a great job of getting crap off of glass. Naturally, you'll not want to disassemble your lens to clean it and so you need a way to selectively clean the exposed glass. Here's how I did it when I did this sort of thing for a living. Get some cotton swabs at a medical supply place. These are the single ended type with wooden sticks that come in a sealed bag designed for autoclaving. No need to buy an autoclave! Just tear open a bag and get yourself a can or bottle of the best grade of acetone you can find. If you're as compulsive as you claim, you can try some place like fischer scientific. I may not have spelled the name correctly! Dip a swab in the acetone, shake off the excess in the trash can (one with no smoldering cigarette butts, please) and roll the dampened swab across only the glass area of the lens surface. You'll immediately see that everywhere you didn't wipe, it's dirty! A kind of film, you might say. This is the accumulation of oil and other pollutants that condense on the glass and get smeared around with lens tissue, etc. After you've made your first wipe, throw that swab away and repeat the process until you've gotten as much of the surface as clean as you can. Now, take a piece of lens tissue and carefully breathe on the lens and polish lightly with irregular motion. This should make a big difference. If you prefer, you can do the polishing with one of those microfiber lens cloths such as the ones sold by Schneider (B&W filters). As always, it is better to keep a lens clean that to keep cleaning a lens! Hope this helps. Bob Zeichner - http://www.razeichner.com
-- Robert A. Zeichner (email@example.com), December 19, 1999.
OK. I work in a modern organic chem lab and have access to all kinds of top grade organic solvents, acetone, ethanol, methanol, isopropanol, chloroform, hexane, ethyl acetate...from Fisher, Aldrich, Acros... They are good at cleaning grease, finger print, smudges, etc that you can see when you look *at* it. To those 'pinpoint's you refer to, NO HELP! I was much much more compulsive than you are, Sir!
-- Aaron Rocky (firstname.lastname@example.org), December 19, 1999.
If acetone didn't remove it I would stop rubbing. There's nothing more to be gained from torturing that lens. I use MC lens cleaner and have yet to have a problem with spot removal, or smearing of the multi-coating. Acetone must be as good - if not better. You may be dealing with a coating defect, nothing you can do will help that.
-- Wayne DeWitt (email@example.com), December 21, 1999.