🔭 Stellar Nomads Telescope Field of View Simulator
—
Drag the sky to pan · scroll to zoom

Telescope Field of View Calculator

This free telescope field of view calculator shows the exact imaging field of view your gear will capture, drawn to scale on real survey imagery. Choose a telescope and camera, and the simulator frames the precise patch of sky your sensor sees — so you know whether a target like the Andromeda Galaxy or the North America Nebula will fit before you set up an astrophotography session.

How to calculate a telescope's field of view

For astrophotography, field of view depends on your focal length and your camera's sensor size:

The calculator runs this math for you and overlays the result on the sky, including any focal reducer or Barlow factor and camera rotation. It also reports effective focal length and f-ratio, capture image scale after whole-number binning, drizzled output scale, sensor resolution, and whether the captured data are well sampled for your site's seeing. Binning and drizzle do not change the field of view.

What you can do with it

Frequently asked questions

What is the field of view of a telescope?

A telescope's field of view is the angular size of the patch of sky your camera captures at once, usually measured in degrees or arcminutes. It is not fixed by the telescope alone — it depends on the focal length together with the size of the camera sensor at the focal plane.

How do you calculate a telescope's field of view for a camera?

FOV = 2 × arctan(sensor dimension ÷ (2 × focal length)), computed separately for the sensor's width and height. A focal reducer shortens the effective focal length for a wider field; a Barlow or extender lengthens it for a narrower field. This calculator does the math and draws the frame to scale on the sky.

What is a good pixel scale for astrophotography?

Image scale in arcseconds per pixel should match your sky's seeing. A common target is the seeing FWHM divided by about three — roughly 1–2 ″/px for typical seeing. The calculator's sampling gauge shows whether your camera and telescope are undersampled, well sampled, or oversampled for the site seeing you select.

How do I get a wider field of view for imaging?

Use a shorter effective focal length — add a focal reducer or use a faster, shorter scope — or use a camera with a larger sensor. Aperture alone does not widen the field of view; it mainly gathers more light and resolves finer detail.

Does a bigger telescope give a wider field of view?

Not necessarily. Field of view is set by focal length and your camera's sensor size, not by aperture. A large, long-focal-length scope can have a narrower field than a small short-focal-length one; bigger aperture mainly gathers more light and resolves finer detail.

How does sensor size affect field of view?

At the same focal length, a larger sensor captures a wider field, because FOV = 2 × arctan(sensor dimension ÷ (2 × focal length)). A full-frame sensor frames much more sky than an APS-C or one-inch sensor on the same telescope. Pick your camera above to see the exact framing.