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Telescope Calculator
Telescope Specs
Aperture (mm)
Primary mirror or lens diameter
Focal Length (mm)
Distance from lens to focal point
Eyepiece Focal Length (mm)
Common: 6mm, 10mm, 15mm, 25mm, 32mm
Barlow Lens
None
2x Barlow
3x Barlow
5x Barlow
Results
Magnification
48
x
Good for deep sky
Exit Pupil
4.2
mm
Comfortable viewing
True Field of View
1.04
°
About 2 full moons
Focal Ratio
f/
6
Max Useful Magnification
400
x
Based on aperture × 2
Limiting Magnitude
13.3
Faintest star visible
Common Eyepiece Combinations
Eyepiece
Magnification
Exit Pupil
Best For