Do Optical Components Need to be Cleaned?

Feb. 14, 2020

Even very simple astronomical telescopes or binoculars should be taken care of as well as possible, including the cleaning of optical components. Many times you will use it to the limit of its ability. When you try to see very faint celestial bodies or subtle details, a little problem will have a very different effect.

Having said that, life is full of regrets, and it is useless to worry about this. Every telescope gets dirty. The dust on the lens or mirror will scatter the light, making the dark sky less dark and bright celestial bodies less sharp, but perhaps less severe than you think. The correct attitude towards the optical components of the telescope should be relaxation-know when to be true, when to open and close.

Customized optical components manufacturer believes that the first measure against dust is protection, and keep the lens cover closed when the device is not in use. If the lid is missing, make one yourself. Use a rubber band on the front of the lens barrel to cover a shower cap, plastic bag, or a dish cloth. A 35mm film plastic tube is ideal for storing standard 32mm (1.25 inch) eyepieces. A clean cloth is also acceptable.

When I store the two reflecting telescopes, let their primary and secondary mirrors face down. This prevents dust from falling on it during storage. The eyepiece should be covered at both ends or packed in plastic bags or small plastic food boxes. Telescope accessory stores sell cheap and durable storage boxes for storing and protecting eyepieces.

Never touch the surface of the lens or mirror. Acids in skin oils slowly corrode optical coatings. If you happen to leave a fingerprint on the lens (binoculars are more likely to happen), you can use the method described below to remove it.

Cylindrical Lenses

Cylindrical Lenses

That's more than enough, let's relax now. Even if there is dust, as long as it is not too serious, it will have little effect on performance. Harold Richard Suiter in his book "Star Testing Astronomical Telescopes" analyzes the effects of dust on the optical performance of telescopes from various subtle details. Want to know his conclusion? "The maximum amount of dust on a telescope optical component that a perfectionist can tolerate is about one-thousandth of the surface area, and the size of a single shield can be about 1/30 of the diameter." In other words, on a 25 cm diameter telescope mirror You can tolerate completely opaque objects with a diameter of more than 8mm. It didn't really matter.

Suiter advises: "Don't decide to clean the mirror because you find that there is dust in the lens barrel at night. All mirrors can't pass such a rigorous inspection." As long as you have taken dust protection measures, let it go.

In addition to not blocking life, there is a good reason to ignore dust. Dirty cylindrical lenses or mirrors will undoubtedly always be cleaned, but scratches are scratches and are irreparable. If done incorrectly, the cleaning process can cause minor scratches or abrasions, and sometimes even if done correctly, it cannot be avoided. A small amount of abrasion doesn't matter, but more is not good. Don't always clean the telescope's optical components.

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