Weather and cloud outlook near you
Cloud Forecast – From Clear Outside will give you the outlook for your local atmospheric conditions.
Calculators for Telescopes
Use the Telescope Nights calculators for quickly working out metrics for telescopes:
- Tool for calculating telescope focal ratio
- Calculate telescope magnification
- Calculate true field of magnification for telescope
Focal ratio (f/)
How to calculate telescope magnification
How to calculate the magnifying power of a telescope? Telescope magnification is calculated by dividing the focal length of the telescope by the focal length of the eyepiece and multiplying the result by the magnitude of the Barlow lens (if using). Or, you can simply use the following tool to calculate telescope magnification. It’ll guide you on the usefulness of the magnification also.
True field of view
The true field of view (measured in degrees) is how much of the sky you are likely to see through your eyepiece when using your telescope.
How to calculate the true field of view of your telescope? It is the apparent field of view divided by the magnification. You typically find the apparent field-of-view (AFOV) value listed in the product description for the eyepiece and magnification is simply the telescope focal length divided by the eyepiece focal length.
Telescope focal Length
Calculators for Binoculars
For binocular users…COMING SOON!…
Binocular Field of View in meters
Binocular field of view in Degrees
Charts / Quick References
Star testing magnifications
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