The lenses of my telescope and binoculars are dusty. What is the best way to clean them without damaging the optic coating?
Best advice is: don't try to clean them! A little dust has absolutely no effect on the images, but a bad cleaning can damage the lenses or their coatings irreparably.
If you must clean them, use the techniques here:
Cleaning the mirrors of reflector telescopes is even less desirable and requires even more care:
Good Question that needs a very precise answer with some good resources.
Things You'll Need : Water, Rag, Canned air, Cotton swabs, Glass cleaner, Alcohol, Tissue.