Resolving power (Dawes limit) = 116/D arc seconds
Theoretical visual limiting magnitude (optical system 100% efficient) = 2 + 5 log10D
In practice, it is likely that the constant 2 in the above equation could be replaced by a value between 3 and 4, particularly when higher magnifications are used.
(where D = diameter of
https://britastro.org/computing/pdf/Con ... rmulae.pdf
Resolution = 5.45 / D where D=
Dawes Limit = 4.56 /D where D=
Starware: The Amateur Astronomer’s Guide to Choosing, Buying, and Using Telescopes, 4th edition, by Philip S. Harrington John Wiley & Sons, Inc. 2007. Pg 6-8.
Light grasp “the ratio of light flux intercepted by a telescope’s objective lens or mirror to that intercepted by the human eye having a 7-mm-diameter entrance pupil.
Limiting visual magnitude m = 2.7 + 5 log D
Smallest Resolvable Angle = wavelength / diameter; 555 nanometers / D (nm) = 114/D in seconds of arc.
Useful magnification range: approximately between 0.2 D and 2.0 D. (“… atmospheric turbulence usually limits the maximum magnification to 400x or less.”)
“Optics and Observing: Telescope Parameters” by Roy Bishop. RASC Observer’s Handbook 2021, page 49. (Royal Astronomical Society of Canada)
Angular Resolution = 0.25 * (wavelength micrometers / mirror diameter meters) with a micron = 10^-6 meters.
Astronomy Today, Chaisson and McMillan, 6th edition, Pearson Addison Wesley, 2008 page119.