Lifespan of optical coatings
This question is more suited for a bird watching forum but since lens and filter multicoats are similar to those found on spotting scopes (plus there are many outdoor enthusiasts on here), so I thought it would be ok to ask. I heard someone saying that optical coatings fade all on their own and that even high end optics need to be replaced every few years as a result. I haven't noticed this in my binoculars so I'm wondering if he was either using too harsh a cleaning agent or his high end optics really aren't so high end. Ithought that they're very hard and durable(?).