Danny Levenson wrote me about lens cleaning:

>I think I remember that you recommend "huffing" on a lens and wiping
>it with a clean, lint-free cloth. If the lens happens to get dirtier
>than this simple cleaning technique will allow, what do you recommend
>as the next best thing to use? I'd like to know what you use both as
>a solution and as a "wiper".
>Danny Levenson

I have learned two tricks for lens cleaning: wash your hands with
a detergent (dish soap works fine) first, and always breath (gently!)
UP onto the glass surfaces to be cleaned (to minimize spit drops
hitting the glass - they form tough-to-remove, sometimes silvery,
spots). I never use the ecologically unsound (regardless of what
is written on the can...) "canned air", but prefer a large hand
air bulb, without a brush (which can easily acquire skin oils).
I first blow the dust off the glass surfaces (I do NOT recommend
blowing into an SLR viewfinder, unless the viewing screen is
removeable - it is likely to do more harm than good). I prefer to
start with a single piece of Kodak lens tissue (avoid any tissue
that may have silicone in it!), prefolded so that there is a flat
surface on the bottom (the folded-up edges and corners form the
"handle"), and used with virtually no pressure on a glass surface
that has been breath-fogged (and only until the fog has disappeared).
Repeat, if necessary, but use a tissue only once. Q-Tips (high-quality
cotton swabs) also work well, and may be better for working on small
areas. I tend to avoid "cleaning cloths", especially if there is a
possibility that they may have silicone in them, and unless they
can be used only once, and then washed (to rid them of potentially
damaging grit). Multicoated lenses may require more aggressive
treatment to remove all traces of oil (though this is not necessary
for good optical performance - removing most dust, and any relatively
thick oil smears is sufficient, with the removal of all dust and the
last traces of oil being necessary for aesthetic reasons only). Any
liquid applied to a lens should be applied with a fresh moistened
tissue or Q-Tip, not dirrectly applied to the lens, where it could
run into the lens and discolor the rear surface of the front or rear
element. Solvents that I have found generally safe and effective:
Windex (or other non-abrasive window cleaner), lighter fluid, alcohol,
ROR (and a few others that are less safe for people....). For REALLY
difficult surfaces, a light paste made of Palmolive dish soap and
water, applied with tissue, and removed with tissues moistened with
windex (followed by breath-and-tissues), has worked the best for me.
Filters that can be immersed in water can be cleaned with Palmolive
applied to a moistened cotton ball, then rinsed thoroughly under
running tap water, and dipped in distilled water with a little
photo-flo added. I tilt them up to drain for a few minutes, and
finish drying them with the hand air-bulb. Everyone's cleaning method
is different - whatever works without damaging the glass surface (or
surrounding materials), and is safe for us humans (and the ozone
layer), is fine.
Hope This Helps