What is Chromatic Aberration in Telescopes?

Chromatic aberration, also known as “color fringing”, is a common optical issue caused by lens dispersion. As a result, the image can look blurred or colors could be obscured, especially in high-contrast situations.

What Causes Chromatic Aberration?

Chromatic aberration occurs when a lens is unable to bring all of the colors to the same focal plane. This happens when different wavelengths of color refract off the lenses at different times. This causes a distortion of the colors in your telescope which can make objects appear blurry.

Which Types of Telescopes Experience Chromatic Aberration?

Chromatic aberration is most prevalent in refractor telescopes. This is because the lenses do not focus all wavelengths at the same speed. Reflector telescopes, like the Newtonian telescope, avoid this by using mirrors. This eliminates chromatic aberration because mirrors reflect all wavelengths at the same speed.

What are the Types of Chromatic Aberration?

There are two types of chromatic aberration: longitudinal and lateral. Longitudinal, or axial, chromatic aberration occurs when different wavelengths do not converge at the same point. This causes areas of the image to be tinted. Lateral, or transverse, chromatic aberration occurs when different wavelengths focus at different positions along the same focal plane. This causes an outline of unwanted color in your image.

How to Fix Chromatic Aberration?

There are a number of ways to correct chromatic aberration. First, it’s important to bring the image into clear focus. This is because chromatic aberration gets worse with less focus. If your focus is on-point and you still experience chromatic aberration, you can use an Extra Low Dispersion glass. These types of lenses can reduce or eliminate chromatic aberration.