[sirto]

I would like to add to the discussion my mod of Tim's work (with the author's permission) for astrophotography: https://paolo.sirtoli.it/astrophoto.html

Every photographer knows very well the exposure triangle: shutter speed, aperture and ISO, but in astronomy usually only aperture and focal ratio are considered. So I added a third dimension to illustrate the basic triad of astrophotography: telescope aperture, focal ratio and image resolution.