Astrophotography configurator

The field of view comes from the scope's focal length and the sensor size, as in the field of view calculator. A target is too large if it does not fit in the frame, and too small if it covers less than 10% of its width.

Detail is the image scale, in arcseconds per pixel. With an average seeing of 2", the ideal range is 0.8 to 2.2" per pixel. Above 5", too much detail is lost, except for very wide fields.

Light collected is a simple index: optic area times the sensor's quantum efficiency. It compares what each setup receives from the target for the same exposure time. It leaves out tracking, cooling and sky quality, shown separately.

The mount is chosen to carry the scope, the camera and about 1 kg of accessories with a 30% margin. Guiding is added from 350 mm of focal length, and a dual-band filter for nebulae under city or suburban skies.

For planets, the tool checks the aperture (120 mm or more for real detail) and works out the Barlow that brings the focal ratio to about 5 times the pixel size. Planet sizes on the image include that Barlow, with Jupiter and Saturn taken at their closest to Earth.

Prices are the lowest found at French retailers (Astroshop, Univers Astro, Enastros, Amazon) in October 2026. They are reviewed regularly.

These figures help you choose, they do not replace experience. My real-life duels between a Seestar S50 and an Askar 71F with an ASI 585MC Pro, on M33 and NGC 6729, show what these gaps look like on actual images.