Telescope Calculator for Magnification, Resolution and Field of ViewThis Telescope Calculator will help you find optimum magnification, field of view of a given eyepiece and limiting magnitude.
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.
A telescope's aperture is the diameter of the primary mirror or lens and is measured in millimetres. The wider the aperture, the more light the telescope can capture. A wide aperture is essential for deep-space objects to gather as much of the faint light as possible.
The focal length of the telescope and eyepiece is the total distance travelled by light from a distant object from the primary optic to the focal plane, where the light is focused.
The apparent field of an eyepiece indicates how many degrees of the sky is covered by the diameter of the circular view as seen through a telescope.
All these numbers are generally printed on the telescope or eyepiece.
Use the numbers from your equipment to gain an insight into the performance of your telescope setup.
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: | |||
