Tools
Free calculators and interactive tools from Starvest.
Telescope Magnification Calculator: Work Out Your Real Power
Free telescope magnification calculator: enter your telescope's focal length and eyepiece to get the real magnification, the max useful power for your aperture, and the exit pupil.
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Telescope Field of View Calculator: Will the Target Fit?
Telescope field of view calculator: enter your focal length and eyepiece to get the true field of view in degrees, and see whether the Moon, Orion Nebula and other targets fit.
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Telescope Limiting Magnitude Calculator: Faintest Star You Can See
Telescope limiting magnitude calculator: enter your aperture to estimate the faintest star you can see, your light grasp versus the naked eye, and what targets come into reach.
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Bortle Scale Calculator: How Dark Is Your Sky?
Bortle scale calculator: answer a few questions about what you can see overhead to estimate your Bortle class, naked-eye limiting magnitude and what is realistically visible.
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500 Rule Calculator: Max Exposure Before Star Trails
Free 500 rule calculator for astrophotography: enter your focal length, crop factor and pixel pitch to get the longest shutter speed before stars trail, using both the 500 rule and the sharper NPF rule.
Read guideTelescope Exit Pupil Calculator: Is Your Magnification Usable?
Free calculator: enter your telescope aperture, focal length and eyepiece to get the exit pupil in millimetres, plus the magnification and whether that view is bright, sharp or wasting light.
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