High end telescope filter

The main optical components of a telescope are the objective lens, eyepiece, and prism. Coatings can reduce light loss and reflection caused by reflection, and improve the transmission rate and contrast of light.

A limiting factor for binoculars that reflect light. When light hits ordinary glass, 4% of the light is reflected from the glass surface (the glass itself absorbs some of the light because it passes through). Telescopes have an average of 10-16 glass surfaces, and their light loss may be 50% or more of the light initially entering the objective lens. Worse still, all reflected light will produce flashes and ghosting images after multiple reflections inside the telescope.

Apply a thin vacuum coating on the surface of the filter, which has a specific chemical composition (usually magnesium fluorine-MgF2). The reflected light on the surface of each filter is reduced to 0.25 or 0.5%, and the transmitted light and contrast are better than those of ordinary coatings.

The thickness and density of the coating must be absolutely standardized, otherwise unexpected reflections and other issues may occur.

So, how do you need to accurately distinguish coating types?

Coating is the most confusing word. In many cases, the interpretation of telescopes can lead people astray. For the sake of distinction, the general explanation is as follows:

Optical coating: This means that only one or more lenses already have an anti reflective film on the surface of the lens;

Full coating: refers to all glass surfaces in contact with air being coated (in most cases, this means less; if plastic mirrors are used, most are uncoated);

Multi layer coating: One or more lenses are coated with multiple layers, and some lenses may only be coated with a single film or some lenses without coating;

Multi layer coating: All glass surfaces in contact with air have multiple layers of coating.

If you have enough money, purchase a fully coated binoculars because of their higher optical transmission and clearer imaging, which is why fully coated telescopes are more expensive than regular telescopes.