How To Clean your Telescope

Last Updated: August 15, 2019

Your telescope is a fixture, and like any fixture in your house, office, or lab, it’s going to collect dust.  This is doubly true if you bring your scope onto hilltops and fields to see the wide-open night skies.  But you love your telescope.  And keeping it in top shape means keeping it clean, so we’ve created a guide to help you learn proper cleaning technique.

The Dos and Don’ts

Did you know dust contains silica?  Silica is a hard substance, and even the smallest particles can cut into your telescope’s lenses.  Trying to wipe the dust off is only going to grind those hard particles across the glass, leaving scratches that’ll make light scatter and ruin your lens performance.  Before you attempt any cleaning, its always a good idea to consult your telescope’s owner’s manual to ensure you are not causing your device any harm.  There’s also a fine balance in cleaning any optic device.  You don’t want to overclean, or you’ll wear down your lens coatings faster, and under-cleaning leads to potential damage.  You’ll also want to take care of your lenses and filters by storing them safely in cases or plastic zippered bags when they’re not in use.

5 Steps for Proper Cleaning

There’s a correct way to clean your telescope, and we’ve outlined the 5 steps you should follow to protect your device and get it looking like new.  Keep in mind that these steps are meant for a refractor telescope.  A reflector telescope requires much more intricate disassembly and should be done by a professional to avoid damage to your device.

1. Remove loose dirt. A manual blowing device or camel hair brush are the best tools to achieve this.  Simply brush or blow the dust from the surface until any visible particles are gone.  Keep in mind that if you blow on the lens with your mouth, you risk trapping dust particulates in the moisture from your breath, which will end up scraping the lens.  Compressed air isn’t great, either, as the chemicals can erode the lens coatings.  There are several great telescope cleaning kits available online, which are worth the purchase to ensure you have the right tools.
2. Wash the lens. Using a lens-safe solution (usually contained in the kits described above) and a cotton swab, gently wash the lens surface in a circular motion until the entire surface is covered.  Never use window or eyeglass cleaners on your lens; they will wear down your lens coating.
3. Use a soft, microfiber cloth for drying. Use a clean cloth and store it in a zippered plastic bag when you’re done to keep it dust-free until your next cleaning.  Never use fibrous paper cloths to clean your lenses, such as paper towels, facial tissues, or toilet paper.  The fibers left behind will damage the glass.
4. Use the blower again to blast any dust off the telescope’s body. Then use a damp cloth to wipe it down, being careful to avoid the lenses.  Avoid using soaps or abrasive cleaners, as they can damage the telescope’s casing.
5. Store your telescope carefully. Remove your lenses and filters and place them in their cases or zippered plastic bags to keep them clean.  Throw a clean cover over your telescope when it’s not in use to keep the dust off and try to keep it from baking in the sun by a window.

Image credit: National Park Service

Protecting Your Investment

Taking your telescope apart should always be left for a professional.  Don’t attempt to clean inside, or you could end up ruining the device entirely.  Try contacting the manufacturer if you feel your device needs a deeper cleaning than you can give it.  Remember, you’ve made a sound investment in your telescope, so keep it clean, keep it protected, and it will perform well for years.

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Header image credit: Lucas Pezeta, Pexels