Telescope Focal Length
Calculate effective focal length, focal ratio, magnification, and exit pupil for telescope setups.
Effective focal length
1,600.0 mm
2.00x factor
Magnification
80.0x
exit pupil 1.25 mm
Focal ratio
f/16.0
effective focal ratio
Effective focal train
The Barlow or reducer changes the focal length seen by the eyepiece, setting magnification and exit pupil.
1,600 mm
Effective focal length
1,600.0 mm
800 mm telescope with 2.00x factor
Magnification
80.0x
20.0 mm eyepiece
Exit pupil
1.25 mm
aperture divided by 80.0x magnification
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