Astrophotography Telescopes: Types & Comparisons

Astrophotography  •  Photography Tips

As more and more tools become available to the common photographer, astrophotography is beginning to see an increase in popularity. Though the specialized genre of photography still requires some astronomy specific equipment, such as the telescopes we will be discussing in the video below, the initial cost of the hobby is more within the realm of many hobbyists. If you’re interested in taking your star photography to the next level, Forrest Tanaka has created an essential guide to astrophotography telescopes in the form of a 30 minute long video tutorial. Take a look:

As Tanaka explains in the video, there are three common types of telescopes used by astrophotographers: Schmidt–Cassegrain, Newtonian, and refractor. Newtonians are most popular, especially among novice photographers, because they are generally lower priced and are still capable of producing quality images. But, take note that Newtonian telescopes don’t come without their own issues. Often, they will require modification and sometimes cause undesirable visual side effects, namely around the edges of the images. Using a crop sensor camera can help combat this, however.

When shopping for a refractor telescope, Tanaka recommends looking for one that offers:

• APO, or apochromatic lens, will help reduce unsightly chromatic aberrations.
• ED – Combined with APO, extra low dispersion glass will greatly reduce aberrations.

Note the chromatic aberration on the bottom, right side of the moon.

Cassegrain telescopes are also a popular telescope, though slightly pricier. Cassegrain generally have longer focal lengths, despite being the shortest of the telescopes. The shortness is helpful when mounting a camera to to it, because it is not as vulnerable to bending from the weight of a DSLR. A Cassegrain will produce cleaner star images, since they eliminate the tails that Newtonian telescopes often create on stars.

The tails on the stars are an undesirable effect of Newtonian telescopes referred to as commas.

The final type of telescope, the refractor, is quite expensive and is generally used by astrophysicists and very serious amateurs. Refractors offer nice contrast to planetary photographers, because there is no mirror blocking the light. Refractors are excellent choices when photographing the sun or planets, as they really allow shadows and cloud shading on the planetary surfaces to show.

“For solar astrophotography, really there’s no other way to go than a refractor with a solar filter.”