Free planning tools · Check equipment compatibility

Telescope camera field-of-view calculator

See the angular frame of your camera and compare it with simple target outlines or your own target dimensions.

No account needed. Results update here as you change the inputs. Measurements stay in this tab unless you choose to share a link; shared links contain the inputs, including any location coordinates.

Your inputs

The starting values are examples. Replace them with your own measurements, prices or documented requirements.

What to have ready
  • Effective focal length, including the reducer or Barlow factor.
  • Active sensor width and height in millimetres.
  • Target width and height in arcminutes, plus your planned camera rotation.
Measurements for Telescope camera field-of-view calculator

Calculated from your inputs

Your plan

The example will calculate here when JavaScript is ready.

What to do next

    Calculation details

    Inputs used in this result

    Compare a change before committing

    Keep this plan, change the inputs and see the difference. The comparison stays in this tab.

    Will the target fit the camera frame at this focal length?

    Use the field of view calculator when comparing a telescope, reducer or camera sensor. The angular frame describes how much sky is recorded. Enter an object’s dimensions from a sky chart, then rotate the camera frame to explore a useful orientation.

    The illustrated target is a size reference, not a photograph or a model of its visible structure. The fit check uses conservative rectangular bounds, which makes the assumption clear when sharing the same framing question with another observer.

    How to use this planner

    1. Enter the telescope, multiplier and active sensor dimensions.
    2. Choose an illustrative target or enter measured angular dimensions from a chart.
    3. Try rotation, inspect the outline and read the projected margins before considering different optics.

    The calculation

    Angular field = 2 × arctan(sensor dimension ÷ (2 × effective focal length)). Effective focal length = telescope focal length × reducer/Barlow factor. Rotation is drawn against a fixed target.

    A worked example

    A 23.5 × 15.7 mm sensor at 600 mm gives about 2.24° × 1.50°, or 134.6 × 90.0 arcmin.

    Example inputs are demonstrations. Replace them with your own measurements, prices or documented requirements.

    Assumptions and limits

    Outlines are original geometric sketches, not sky photographs or accurate object boundaries. The Moon example is a fixed 30 arcmin reference; its apparent size varies. Enter target dimensions from your own chart. Framing alone does not establish resolution, visibility, corrected image circle or image quality. Rotating the frame changes the bounding space around a target.

    Questions about this calculation

    Does fitting the frame mean the target will be well resolved?

    No. Framing answers a size question. Pixel scale, seeing, tracking, signal and the corrected image circle need separate checks; a target fitting inside the outline does not settle those decisions.

    Why are there both a target outline and dashed bounds?

    The outline is an illustration; the dashed rectangle is the conservative size envelope used by the fit calculation. A real irregular target can differ from both, so leave room for framing and processing.

    Put the result in context

    From planning to choosing

    Would you rather share an eyepiece or a screen?

    Read our Odyssey Pro desk review, then compare the three telescope choices for shared observing. A smart telescope is a different route from the modular equipment these tools can help you plan.

    Read the Unistellar Odyssey Pro review

    Compare the three picks and current offers