Clean Lenses: How to Clean Your Telescope Lens

how to clean telescope lens

Keep Your Lenses Clean in a few Simple Steps

Telescopes allow us to see the beauty and wonder of the universe from the comfort of our own humble backyards. From distant stars to planets and nebulae, few things are out of reach to a high-quality, well-maintained telescope.

Of course, using your telescope over time can cause the same wear, tear, and smudging as any other home gadget. If your telescope lenses get dirty and smudged, you won’t be able to see much of anything at all! Regular cleaning and maintenance will keep your telescope in top shape and help you see even the most distant stars.

By following a few simple steps, you can learn how to clean your telescope lens! With only a few ingredients and a few minutes of your time, your telescope will be like new in no time.

Easy Guide to Clean Your Telescope Lens

Retro telescope lens

Before you get started, there are a few items you’ll need to clean your telescope lens. To kick things off make sure you have the following:

  • Compressed air can
  • Glass cleaning solution
  • Microfiber cloth

Once you have gathered all of the items you need, you’ll be ready to get started cleaning the surface of your lens.

Compressed Air First

Use the can of compressed air to blow away any of the larger dirt and dust particles that might be on the optical surfaces of your telescope. You might be thinking, “I’m just going to use a cleaning fluid anyway, why would I pre-clean with compressed air?” Trust us, you’re not going to want to skip this step.

Larger dirt and dust particles can be wiped away the same as smaller specks of dust while you’re cleaning; however, larger particles can damage the lens surfaces while you’re cleaning. If you don’t blow away these larger particles first, you’ll run the risk of permanently damaging your telescope lenses.

Also, don’t try to just blow these larger particles off. While it can be tempting to go with an “all-natural” approach, your breath contains saliva particles and potentially even mucus or other things you absolutely do not want coating your telescope eyepieces. Stick with a can of compressed air; you’ll thank us later.

Hold the can of compressed air upright. When you’re ready to clean, slowly press the trigger to start the stream of air. Be sure to leave a few inches of space between your telescope lens and the compressed air can. You don’t need to hold the air can right next to what you’re trying to clean.

There’s no need to shake a can of compressed air prior to using it. In fact, we actually recommend that you don’t shake it. There’s really no need, and doing so could actually be dangerous.

Slowly spray the compressed air along the optics to remove all of the large, loose particles that have collected on the lens surfaces and optical coatings. Make sure that you’re aiming away from the optics so that any dirt particles are blown off the surface and not just redistributed onto another part of your telescope.

Once you’ve removed all of the surface dust, you’ll be ready to move onto the next step. Don’t worry if there are some stubborn particles: we’ll get them in step 2! As long as there aren’t any large particles remaining, you’re ready to clean your telescope further without risking a scratch on the lens.

Use a Lens Cleaning Solution

Telescope Lenses Cleaning Solution

Now we move on to the deep cleaning that will make your telescope lenses shine like new. You’ll remove all of the grit particles on top of the eyepiece surfaces with a cleaning solution. Most of the cleaning liquids you’ll find are some form of methyl alcohol or isopropyl alcohol-based solution.

It doesn’t matter which alcohol base you choose to use since either will do the job well. We don’t recommend using water alone even if you choose a distilled water solution to clean your telescope lens. Even distilled water has a habit of not drying cleanly and leaving behind smudgy, streaky marks

If you use heavily distilled water you will reduce the chances of leaving behind any streaking, which is caused by mineral impurities in the water staying behind on your telescope eyepieces once the water dries. It should be noted that it’s very hard to achieve an entirely streak-free shine with water. Given thatalcohol-based lens cleaning solutions are readily available, we recommend you stick to those and ditch the water.

Using a professional cleaning solution is very important. Some telescope enthusiasts will try to create their own diluted alcohol cleaning solutions by mixing alcohol and water. It is better to use a professionally-mixed solution.

If you try to mix your own and you use too much alcohol, it can actually dissolve the protective coatings over your telescope optics. It will also likely dry up too quickly to actually be of any use in removing the dust particles.

If you want afully prepared solution, you can look into buying a full lens cleaning kit that will have exactly the right cleaning solution, along with the microfiber cloths and other cleaning instruments. Simply apply the cleaning solution to the surface of your optics to start the cleaning process.

Once you’ve applied the alcohol-based cleaning agent, use a circular motion to wipe the telescope eyepieces clean. Be sure not to apply too much pressure; your telescope is tough but it can crack or be damaged from overly aggressive cleaning.

Once the telescope eyepieces are clean and free of any remaining dirt and dust particles, you’ll be all set to move on!

Detail the Smaller Pieces

With your lens cleaning solution and a finer cleaning instrument such as a cotton swab, you can carefully clean out the smaller and harder-to-reach parts of your telescope lens. It’s important to pay extra attention to these parts of your telescope as dust and dirt can easily build up and prevent you from having the best possible view of the stars.

Make sure that you take extra care to not use too much force when cleaning these smaller areas as they’re usually the most delicate parts of your telescope. Also, be especially cautious to only use a very small amount of cleaning solution on your cotton swabs.

If you saturate the cotton ball with too much cleaning fluid you’ll run the risk of having excess fluid drip into the inner workings of your telescope. Fluids that get below the lens will be extremely difficult to remove without disassembly, which will not only void your warranty but also increase the possibility that something gets damaged during the cleaning process.

The technique here should be the same as the main lens and larger parts of your telescope. Use a circular motion with very light pressure to gently brush away any dirt and dust particles that have built up on your telescope eye optics.

Don’t Over-Clean Your Telescope Lens

Unlike cleaning your room when you were a kid, there is such a thing as cleaning too much when it comes to your telescope lenses. Believe it or not, unless your telescope is getting excessively dirty (in which case we need to ask if you’reusing your telescope correctly), you probably don’t need to clean the main lens more than once a year!

That’s right: cleaning once per year should be more than enough to keep your main lens in perfect shape. When it comes to the more frequently used eyepiece, you’ll need to clean it more often. Since the eyepiece is coming into contact with your skin, and therefore the oils on your skin, you’ll need to pay more frequent attention to keeping the eyepiece in top-shape.

Even still, you shouldn’t need to clean your eyepiece more than once every few uses, unless you’re stargazing nightly. Cleaning too often can strip away the protective coating over your lens optics, making your telescope more vulnerable to dirt and dust buildup in the future.

Keep Your Telescope Clean for Life

By following this simple guide, you can keep your telescope lenses clean with three simple steps. As you’ve learned, it’s not hard to learn how to clean telescope lenses, and a little effort with routine cleaning will go a long way towards keeping your telescope performing at its best.

Considering that high-quality telescopes and theirequipment can be quite expensive, it’s well worth it to invest in an inexpensive cleaning kit and materials to keep your telescope shining like new. Proper maintenance will allow you to avoid expensive replacements and focus on stargazing.

With your freshly cleaned telescope, you’ll be ready to keep exploring the stars like a professional astronomer. Who knows, you might even discover something special without ever stepping foot outside your backyard!


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