Question

Focal Ratio= f/6

Diameter=1.0m

Focal length= 6.0m

How can the field of view, in arcmin,  of this telescopic system be calculated?

Answer 1

The focal ratio, or f/stop, of any lens system (including telescopes), is computed by dividing the focal length by the clear aperture (usually expressed in millimeters). In other words, the focal ratio is the ratio of the focal length and clear aperture. Thus:

TELESCOPE FOCAL LENGTH / CLEAR APERTURE = FOCAL RATIO

Here, focal ratio = f/6

OCULAR FIELD STOP DIAMETER / TELESCOPE FOCAL LENGTH x 57.3 = FOV(field of view)

FOV = 57.3/6 = 9.55

Field of view = 9.55