800 mm scope, 20 mm eyepiece

Example inputs. Not a list of telescopes.

Worked example

Do not look at the Sun through a telescope, finderscope, or eyepiece unless a certified full-aperture solar filter is fixed on the objective.

Magnification 40×

Exit pupil 2 mm

M = F_scope / F_eyepiece. Exit pupil = aperture / M.

Resolution form 1.45 arcsec

116 / aperture mm is one resolution form. It is not a forecast of seeing.