basic

Telescope Angular Magnification and Resolving Power Calculator

M = f_obj/f_eye; θ_min = 1.22λ/D (Rayleigh criterion).

Calculates telescope angular magnification and minimum resolvable angle using the Rayleigh criterion. Larger aperture and longer focal length objective improve performance.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

M = f_obj / f_eye; θ_min (arcsec) = 1.22 × λ / D × 206265

In depth

Calculates telescope angular magnification and minimum resolvable angle using the Rayleigh criterion. Larger aperture and longer focal length objective improve performance.