is my lens damaged?
Just bought a lens for my Mamiya and it looks like someone has tried to polish the lens with their shirt or something as it is a bit smudged. Can't quite see if the coating is fully damaged. should i polish it with any sort of special cloth and/or with any liquid? or should i just leave it?
If it truly is smudged, a drop (only a drop) of lens cleaner on some lens tissue or a fresh microfiber lens cloth used very gently will do the trick. Blow or brush off any dust that may be on the lens first.
Otherwise the lens may have what gets called "cleaning marks" which comes from over zealous cleaning. The fine scratches, aka cleaning marks are not removable, but usually don't cause significant problems either. They can make the lens more prone to flare which can be avoided by using a lens hood.
If you use a lens brush, make sure it's clean and don't ever "pet" it (you will transfer oils from your skin to the lens).
If the smudging doesn't come off with careful cleaning you should return the lens if possible.
I would first give it a good cleaning. Perhaps a bit (but not much) more agressive than what bdial says. Lens coatings are very durable, and I have seen lenses that looked pretty bad be fine with a good cleaning.
I looked at a 20mm Nikon lens at a camera show, and thought the coating was damaged. The booth owner wet his thumb and scrubbed the lens to show me it was just dirt. Bought the lens, gave it another good cleaning and there is no visible scratches or 'cleaning marks'. Just shows one shouldn't give up to easily.
First, blow off lose dust and particles from surface of the lens using canned air. Then put a small amount of lens cleaning fluid ON LENS CLOTH then wipe in circular motion ONCE with little pressure. Then take a new cloth and do the same few times. Wait a bit and repeat this process one more time.
Lose particles on the lens can scratch the surface, hence the first two steps. Using lens paper is a bit more risky than microfiber lens cloth. If a particle gets trapped on the thin paper, it is more likely to get dragged across the surface than with microfiber cloth. If the lens is very dirty, I'd advise against using paper of any kind - no matter what it says on the product. Also, never spray cleaning solution directly to the lens.
You should need no more than gentle pressure to clean any lens. Aggressive cleaning can cause problems.
What vintage is the lens because early coatings are waaaaay soft and you can wipe them right off.
If it's a more modern design it will tolerate more but use caution in any event.
Thanks all of you - really helpful.
Originally Posted by brucemuir
(yes it's only 5 or so years old i think)
In which case, just use standard (read: GENTLE) lens cleaning practice.
Originally Posted by BuddhaBelly
The fragile coatings are usually found only on the very first coated lenses, say from about 1940~ to the very early 50s. They're not often found, and not all early coatings were/are fragile.