You will need a window cleaner solution with alcohol (mostly colored in blue), some cotton swabs, a bulb-type puffer (available in most photo shops) and some Kleenex tissues. Avoid tissues with perfumes or lotions, as they will leave a film on the lens. Prepare a clean work area, such as a freshly washed kitchen table.

First, use the bulb-type puffer to blow off any dust or loose particles from the lens surface. Don’t blow the dust off with your mouth, as droplets of moisture can get on the lens, causing spots. If the eyepiece has particles stuck to it that can’t be blown off, moisten (do not soak) a tissue with window cleaning solution and gently blot the surface, without rubbing. On smaller lenses, use a cotton swab or fold a tissue into a steep triangle, moistened with window cleaning solution. Use the puffer again to blow off any more dust.

Second, moisten (do not soak) a cotton swab or tissue with window cleaning solution and gently wipe from the center out to the edge, using a circular motion. Move the cotton swab or tissue slowly enough so that the cleaning fluid appears to “follow” the cotton swab or tissue around and is re-absorbed. If you move it too quickly, some of the liquid will “break away” and dry separately, leaving spots.

You’ll probably use several tissues or cotton swabs to thoroughly clean a lens. Use a new tissue or cotton swab after each swipe; this will prevent any contaminants from getting back onto the lens or scratching it. Do not touch the lens with your fingers, as the grease on your hands and fingers will cause smudges. Also, be careful the grease from your hands and fingers does not get on the cotton swabs or tissues; it will smudge the lens. If it does, throw it away and use a clean one.
Cleaning the edge of a lens is the most difficult part, especially where the cotton swab or tissue is lifted from the surface. Don’t use too much liquid or put the liquid directly onto the surface being cleaned, because capillary action could draw the liquid inside. Try folding a tissue into a sharp point, moistening it slightly and use it to wipe around the edge.

If, after cleaning, any spots remain, try “fogging” the lens surface with your breath, then wiping it with a cotton swab or tissue moistened with window cleaning solution.

Your eyepieces should be stored, dry, and in as clean condition as possible, optically and mechanically. This will make them ready for use on demand. Keeping your eyepieces as clean as possible during use upholds their condition and performance, and will make preparation for storage quite easy. After inspecting the condition of your eyepieces and making sure they are clean and dry, place on the lens covers and store them indoors, protected in a suitable case.

By making sure eyepieces are clean, the chance of transmitting debris to the scope optics is reduced or eliminated. Properly maintained, Sky-Watcher eyepieces will provide long-lasting, consistent, and dependable performance.