Astrograph Telescopes

For serious astrophotographers, a wide-field optical tube telescope with quality optics and suitable specifications is key to producing successful images. Astrograph telescopes come in many different specifications and designs, so each model can be oriented or preferred for a different type of imaging (eg. solar, terrestrial, deep sky, etc). Some common designs of astrograph telescopes include the Newtonian, Ritchey-Chrétien, Riccardi Honders, and Catadioptric optical tubes. Choosing an astrograph telescope depends on how the astro-imager wants to observe. They must take into account its focal length and focal ratio, aperture, optical coatings, and how suitable it is for the camera they intend to use.

A key specification that is very important to consider when choosing an astrograph is the focal ratio in relation to the aperture. This is important because the focal ratio determines the magnification and field of view the observer will get. Therefore, if the observer intends to mainly view deep sky objects with lower surface brightnesses, a shorter focal length will reduce magnification and increase the field of view since most deep sky objects tend to appear very large but not bright. Astrograph telescopes with slower focal ratios such as an f/12 will provide higher magnification and a smaller field of view; better for planetary observing.