One of the lenses I'd gotten with a Canon AE-1 Program was cloudy with a chance of rain (based upon droplets inside!). Took a couple of photos to verify it was in bad shape. TEST SUBJECT: Tou/FiveStar FD 75-200 f4.5 zoom DISASSEMBLY: Three tiny phillips head screws in barrel just fore of the aperture ring by 1/8 of an inch. Removed convex lens element just under metal O-ring after screwing casing free from barrel mount. INITIAL CLEANING: Tried alcohol, glass cleaner, peroxide and cold cream. INITIAL RESULT: None of these methods worked in removing whatever kind of film buildup occured. Suspect some kind of lubricant was used within the camera lens and it "hazed" onto one of the internal elements. INTERMEDIATE CLEANING: Used cordless Dremel tool and felt-wheel for buffing, with a mix of baking soda dissolved into cold tap-water on same convex lens with problematic glazed "coating". INTERMEDIATE RESULT: The lens is noticeably cleaner, but still seems a touch soft or "foggy". Would be okay if shots do not necessarily have to be really sharp. Problem would be magnified if focus is off, but is easier to focus anyway. Some people may think I'm nuts for taking apart a lens. But since it would cost more to have it professionally cleaned/repaired than to buy another, then it's fair game for anything I can try. SUMMARY: The baking soda solution DID NOT appear to scratch the element buffed out. The inside glass was cleaned but DID result in minor scratching (with no real impact). Would I suggest this to a questionable low-end lens: yes. Would I suggest it for a prime or any under warranty? Heck no!