Warning: I almost ruined a $300 lens using isopropyl alcohol on the glass

I was cleaning a Canon 50mm f/1.4 yesterday and the coating started peeling right off after one pass with 91% IPA. Has anyone else had this happen or did I just get a bad batch of cleaner?

2 comments

2 Comments

kevin_martin9d ago

91% is way too strong for coated optics. I use 70% isopropyl and even then I barely wet the cloth, never let it pool. The coating on that Canon 50 1.4 is notoriously delicate, I've seen people strip it with just a foggy breath and a microfiber. You probably didn't get a bad batch, you just used a solvent that's harsh enough to soften the coating. Next time try a lens pen or a drop of distilled water with a clean lens tissue, it sounds gentler but it works.

spencer_chen69d ago

67% is where it's at but honestly my dumb self once used nail polish remover on a kit lens thinking it was just "strong cleaner" and watched the coating bubble up like a pizza crust. The Canon 50 1.4 coating is so fragile I swear my breath fogged it up and a tiny flake came off once. You're not alone in breaking stuff, I've got a UV filter sitting in shame that looks like a tie dye shirt from my mistakes.