Telescope Calculator

2nd June 2010

By Tim Trott

What's the optimum magnification for my instrument? Is the field of view of a given eyepiece too small to see all of the Moon? Is there a minimum magnification for my scope? What sort of limiting magnitude should I expect with an instrument of a given aperture? You can find answers to all these questions and many more besides with this interactive telescope calculator.

Telescope aperture	Telescope focal length	Eyepiece focal length	Eyepiece apparent field

Here is an analysis of your telescope's performance using the parameters selected above:

Telescope aperture (d) and focal length (F)

Telescope eyepiece focal length (25mm & 10mm) and apparent field (52)

About the Author

Tim Trott

Tim Trott is a creative photographer, traveller, astronomer and software engineer with a passion for self-growth and a desire for personal challenge.

Further Reading

All About Telescope Eyepieces

The image that is acquired through the lens of a telescope becomes visible through an eyepiece. Each eyepiece provides a given magnification This is determined by the ratio between the focal length of the objective and eyepiece.

Sky Orientation through a Telescope

Looking through an eyepiece, the sky will take on a different orientation depending on which telescope you use. This is due to the telescope optics reflecting and refracting the light in different ways.

How To Make and Use a Bahtinov Mask

The Bahtinov mask is a device used to accurately focus astronomical telescopes. It is named after its inventor Pavel Bahtinov.

Buying Your First Telescope

Buying your first telescope can be a daunting task. We show you what you should look for and how to quickly get up and running.

Telescope Calculator

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