What is the field of view of the telescope?

The angular diameter of the sky area where the telescope can image well is called the field of view or viewing angle (ω) of the telescope. The field of view of a telescope is usually determined at the time of design. The field of view of a telescope is inversely proportional to the magnification. The larger the magnification, the smaller the field of view. Different optical systems, different imaging quality (caused by aberration), different aperture and different focal length determine the size of different fields of view of the telescope (for celestial photography, the size of the negative or CCD will also restrict the size of the field of view). Reflective telescopes have the smallest field of view, generally less than 1 degree; Refraction telescope is large, which can reach several degrees; The reflective telescope has the largest field of view, which can reach more than ten degrees or even dozens of degrees.

Want an example? This is good:

Niu Fan 150750, install PL20MM eyepiece and ask what is the field of vision?

Answer: the magnification is f object /F grid = 750mm/20mm = 37.5.

True field of view = apparent field of view/magnification

The apparent field of view of Prossr eyepiece is 50 ~ 55, so the actual field of view is about 65438 0.4.