Can I use spectacle cleaning wipes (alcohol based) to clean camera lenses? I know it shouldn't be used on plastic (like LCD), but is it OK for lens?
Modern lenses have coatings on them that are pretty hard. While it's not impossible to scratch an lens with a modern costing, it is hard as long as you're taking precautions to make sure you don't have grit on your lens. I clear the lens of debris, and then huff with my breath, followed by gently wiping with cotton. That can be a clean pair of underpants that are no longer fit for use. :-)
You don't need fancy chemicals or expensive lens cloths. I'll admit to some hesitation before doing this to my first really expensive lens: a Leica ASPH. :-) Haven't looked back. I was encouraged by a very competent and well published photojournalist. This is how he cleaned his lenses, and they were all pristine. My lenses are also pristine on their front elements.
Be careful with any kind of wiping. Never use physical wiping as the first way of removing dirt. That should be a gentle blowing or a soft lens brush. Only then wipe. The reason for this is that if any hard particles are on the lens when wiping, they can scratch as they are being ground into the lens. Wiping is for removing soft things stuck to the lens, like a fingerprint, the remnants of a dried water drop, etc.
I don't know if alchohol is OK. Certainly it's fine for bare glass, but the front of camera lenses aren't glass but some kind of coating. Those may not like alchohol. The best answer would be in the directions that came with whatever lens you want to clean.
I like to use distilled water when wiping a lens, which should be safe with any lens. Fortunately distilled water is usually handy and available. Exhale gently on the lens to fog it. That will deposit essentially distilled water. By exhaling gently I mean a sort of soft huffing with your mouth open the whole time close over the lens, with no sudden burst of air that could cause spit to come along. This doesn't work in the desert when the lens is warmer than your breath, but most of the time it is effective enough.
I treat camera lenses as much more sophisticated and sensitive than my eye glasses. Before wiping the lens down I always use an air compressor (i.e. the keyboard cleaner bottles you can get at any office supply store) to blow any particles off the lens. Then I spray lens cleaner on the lens...I always use a lens cleaner that specifies use for camera glass (as opposed to just eye glasses). I am not a chemist and don't know if there is any difference in the products, but I don't take any chances with my lenses. Then I use a soft microfiber cloth and wipe in one direction, and I NEVER SWIRL the cloth around, because particles will get picked up by the cloth that can scratch the lens. I swipe in one direction then use a different part of the cloth to swipe in another direction. I repeat until the glass is clean.
Modern lenses (especially higher-end lenses) have special coatings on them which protect them from minor scratches and blemishes, but I would never take any chances.
Personally I do not allow anything other than a professional camera lens cleaning solution or clean water to clean my lenses. Right now "ECLIPSE lens cleaner" and PEC pads are what I use when a lens is really dusty or a clean microfiber cloth with or without water very gently used when I do not have the ECLIPSE and PEC pads handy.
My fear of other, any non-professional, cleaning solutions is that they will affect the various coatings on my Canon "L" series lenses and filters.
When my lenses were primarily of the lower-end third-party variety and they had low-end filters on them I did not take this kind of care with them. I would even clean the filters using a bandana out of my back pocket.