**Field of view of an eyepiece**

**Formula :**

C '= C^{o} / (F / f) * 60

C '= Field of view in minutes of arc

C^{o} = Apparent field of the eyepiece in degrees

F = Focal length of telescope or telescope

f = focal length of the eyepiece

Here is an example :

Use of a 40 mm eyepiece offering an apparent field of 43^{o} with a telescope with a focal length of 2 mm:

43 / (2000/40) * 60 = 51,6 ′ of arc

The eyepiece with this telescope will provide a field of view of 51,6 ′ of arc

**CCD camera field of view**

**Formula :**

S = 205 x P / FL

S = Field of view covered by one pixel in arc second

P = Physical dimension of a pixel in microns

FL = Telescope focal length

It remains to multiply by the number of pixels in width and height. To convert to minutes of arc divide by 60.

Richard Beauregard

Sky Astro - CCD

Revised 2022/06/04