Resolving power is the smallest angle a telescope can separate, which decides whether a tight double star shows as two points or one blurred blob. It depends almost entirely on aperture: bigger mirrors and lenses resolve finer detail. This calculator gives two classic figures in arcseconds. The Dawes limit, 116 divided by the aperture in millimeters, is an empirical rule for splitting equal magnitude double stars. The Rayleigh limit, 138 divided by the aperture in millimeters, is the stricter physical diffraction criterion. Enter your aperture to see both, along with the useful magnification you need to actually perceive that separation. All math runs locally in your browser with nothing uploaded.
Resolving power is the smallest angle a telescope can separate, which decides whether a tight double star shows as two points or one blurred blob. It depends almost entirely on aperture: bigger mirrors and lenses resolve finer detail.
Yes. Telescope Resolving Power Calculator is completely free, with no sign-up and no usage limits.
Yes. Telescope Resolving Power Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Telescope Resolving Power Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.