Calculator for telescopes / astrophoto.

Input focal length: 10 - 4000mm
aperture: 30 - 500mm
focal l. of eyepiece: 2 - 40mm
Width of film/CCD: 5 - 60mm
Height of film/CCD: 5 - 60mm
declination of object: 0 - 80°

Values for astrophotography.
Longest exposure time for round star images with fixed camera mount and the image scale.
Calculated values for telescopes.
Exposure time Sec f 1:
Image width Degr. Max.Resolution Arcsec
Image height Degr. Magnification
Exit pupil mm

The calculations of exposure times in relation to magnitudes are left out from this calculator.
The right exposure time of a deep-sky astrophoto is when the background sky is barely visible. This can vary a lot for the same spot of the sky (even during only one night) depending on factors like light pollution, sky glow, moonshine, snow, aurora...

J Käld 2004 Previous Page     Main Menu