In order to take the best care of your telescope, you should also clean its optics. However, let's begin by stating that you should only clean optics when absolutely necessary. Don't be too alarmed if only a few specks of dust appear.
The fact of the matter is that over cleaning can result in permanent damage to your equipment such as scratched coatings or premature aging of the special coatings on your optics.
Since there are different telescope types constructed with different optical systems, the methods of cleaning vary.
In this article we will cover:
For easy navigation, you can click on your specific inquiry listed above to go directly to that section in which you have an interest. Below, we will discuss the necessary steps each cleaning method requires.
4 steps for cleaning eyepieces and lenses of a Refractor or Catadioptric telescope
Due to oil from one's eyelashes and misplaced fingers, telescope eyepieces often require the most cleaning out of all your optical equipment. Additionally, the front lens of a refractor or a catadioptric telescope can sometimes gather dust and a filmy residue may form. If that occurs, a quick thorough cleaning is in order.
There are four easy steps you can take in order to optimally clean your eyepieces and lenses.
There is no need to go out and buy a dedicated lens cleaning fluid. You can mix your own lens cleaning fluid. Use a 50/50 ratio of distilled water and isopropyl alcohol along with a few drops of dish washing liquid.
Step 1 - With a bulb-blower or a can of compressed air, give a few bursts of air on your hand to ensure that only air is coming out. Once you've confirmed that miscellaneous particles are not exiting your tool (bulb-blower or can of compressed air), use your tool to blow any loose dust and dirt particles off the lens surfaces of your telescope.
Step 2 - Use a lens pen or soft camel-hair brush to remove any additional loose particles that remain after step 1 is compete. Make sure to be very gentle with your brush strokes.
Before moving on to step 3, make sure you have removed as much dust as possible through the previous two steps. You really want to avoid grinding any dust particles into the optical surfaces.
Step 3 - Moisten a cotton ball or Q-tip with a few drops of cleaning fluid (mixture mentioned above) and very gently wipe the lens with the moistened cotton ball or q-tip. Do not apply pressure and do not wipe in a circular motion. Wipe the optical lens softly in a straight line. It is also ideal to wipe with an unused surface of the cotton ball or q-tip with each stroke. Using a new cotton ball or q-tip for each stroke may be necessary.
Step 4 - With a dry cotton ball, gently brush off any remaining moist areas from the optical lens. Finally, simply let the lens dry and you're all set.
3 lens cleaning tips
- Cleaning solution made for eyeglass use should not be used because it can leave a chemical residue behind.
- Never apply lens cleaning fluid directly to a lens because it can seep into the interior of eyepieces.
- Do not take eyepieces apart due to the fact that they can be difficult to reassemble.
10 steps for cleaning mirrors of a Reflector telescope
For reflector telescopes, such as Newtonians or Dobsonians, the primary and secondary mirrors typically only require an occasional blast of compressed air to remove a few specks of dust. Under normal use, these types of telescopes should not need cleaning more than once every two years or so.
However, if a thick film of grime develops, then a quick mirror wash may be beneficial. In just ten simple steps outlined below, your mirrors can be back to pristine condition.
Before you begin cleaning, make sure you remove any rings from your fingers to avoid accidental scratches.
Step 1 - First remove the cell from the optical tube and loosen the three clips to remove the mirror from its cell.
Step 2 - Carefully place the mirror on a towel. Then, with a bulb-blower or a can of compressed air, give a few bursts of air on your hand to ensure that only air is coming out. Once you've confirmed that miscellaneous particles are not exiting your tool (bulb-blower or can of compressed air), use your tool to blow any loose dust and dirt particles off the mirror surface.
Step 3 - Use a soft camel-hair brush to remove any additional loose particles that remain after step 2. Make sure to be very gentle with your brush strokes.
Step 4 - Tilt the mirror on its edge in a sink over a folded towel (to prevent slipping) and wash off any dirt from the mirror by running cold water over the front of it.
Step 5 - Fill the sink with about 4 inches of warm water and add a few drops of dish washing liquid.
Step 6 - Submerge the mirror in about half an inch of water, laying it flat on the towel (reflective side up). Then gently swipe the mirror with cotton balls in straight lines across the mirror's surface. Use one cotton ball per swipe, do not reuse them.
Step 7 - Rinse off the mirror with cold water as you drain the sink.
Step 8 - Use distilled water for a final rinse.
Step 9 - Allow the mirror to completely dry by standing it on edge (still positioned on the towel).
Step 10 - Reassemble the mirror to your telescope but make sure you do not over tighten the clips when replacing the mirror in the cell. Once finished, properly collimate the optics.
With this step-by-step guide on how to clean telescope eyepieces, lenses and mirrors, you should be all set for proper telescope maintenance.
If you need additional guidance on telescope storage, take a look at Telescope Storage - Best Practices.
If you need a quick refresher on collimating your telescope, review our article on What is Collimation.
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