Long story short I've seen people rub away at their glass with their shirt or towel and to me this is the equivalent of scratching a chalkboard with your fingernails.

Perhaps its out of ignorance so I decided to make a video on it. Please make sure you have a waterproof optic that is tightly closed when you do this lol. Also works great on sunglasses or prescription glasses.

Someone in the NV forum took my advice on how to clean their sacrificial cover and had great results. Basically you can apply it to a lot of things that needs to be clear yet can't get scratched which in turns degrades clarity in the long run.

Link to video:  https://www.youtube.com/watch?v=067CGRg6yfQ

http://www.bhphotovideo.com/bnh/controller/home?O=&sku=1100348&gclid=CjwKEAjw3_ypBRCwoKqKw5P9wgsSJAAbi2K9QZX9l7fN-67EykniQZqPnHQXJzrAqMM63eiJrVFuYBoCba3w_wcB&Q=&is=REG&A=details

So you think a lens pen is too rough.... but using a dish detergent, that is made to strip away grease and dried food particles, along with using your fingers, is perfectly fine?  How do you know that the dish soap is not stripping away the multicoating put on many glass lenses?  FFS, please tell me you're not doing this to your Razor.

For one he flushed with plenty of water to get any abrasive particles off of the glass. At that point a little mild dish detergent and your finger is not going to harm the lens coatings. Most of the companies that manufacture optics use solvents such as acetone, alcohol, acetic acid or lacquer thinner to clean the raw glass. The OP's method is a perfectly acceptable method to clean optics. The lens coatings are a lot tougher than you think.
Just Sayin'...
 

The reason I mentioned was the lens pen is that you are basically rubbing the dirt and debris that is resting on the glass already. Similar to how if you don't properly wash your car your clear coat is getting abraded. Sooner or later you're going to get swirls.

Ask an optician if you have any doubts.

Just trying to show a different way of doing things.

Eotech says to use a water based glass cleaner and a clean cloth. I use a water based glass cleaner and a clean cloth

I'm not refuting that a lens pen is a bad idea, I'm saying that using dish detergent and your finger is also a bad idea.

You never explained how you know that the dish detergent isn't going to strip the optical coatings on the lenses.

       
As I stated earlier, the lens coatings are lot tougher than you would think. Optics manufacturers use a lot stronger solvents to clean their lenses than dish detergent. For years the preferred cleaners were the Tri-Clor solvents, think Gun Scrubber, and toluene, but pretty much all the manufacturers had to stop using them because of the environmental issues with them. This happened more than 20 years ago when the coating were not nearly as resistant to scratching as they are now. They now primarily use Isopropanol, acetone and either acetic acid or vinegar to clean lenses with some limited use of various thinners to clean the glass. The real enemy of lens coatings is anything abrasive. That is why you want to flush with as much liquid as possible to get any abrasive particles off of the surface of the lens. Water is fine but Deionized water is better, it won't leave mineral residue behind. Also canned or compressed air or one of those old bulb brushes will help get abrasives off of the lens surface. Just Sayin'...



 

Zeiss advertises specifically not to use acetone or benzene as it can break down various materials.  Alcohol, which is widely accepted and used in lens cleaning, does not clean in the same manner that a dish soap does.

All I'm saying is that I would at least shoot the manufacturer an email to see what they have to say before using this on a high-end optic.  Proprietary coatings may not react well to something like this and we'd never know until it was too late.

I use a cleaner that the movie industry uses on film. Seems to work well.

US Optics' take on cleaning rifle scopes

I wonder if Kimwipes would be a better alternative to untreated tissues.  We used to use them in the lab for wiping down lenses and cuvettes.

FWIW, I clean my sunglasses and shooting glasses the same way as the OP, using Dawn.  For reference, I have Costa and Wiley X brands.  I have never had an issue.  I haven't tried it on my optics, although I haven't had an issue using traditional methods, either.  I would guess that a simple non-ionic surfactant isn't going to harm coatings designed specifically for optics that see battlefield use.

Probably would since they are specifically made for such purpose.

I have been using the process in the video and I haven't noticed any damage to my optics. I can't imagine that dish soap would contain anything more harmful than acetone.