On the last page, folded and yellow, her grandfather had written only one sentence beneath a doodle of a crescent moon: “Measure what you can, but remember — some things are wider than any field of view.” She folded the page shut, looked up, and smiled into the wide, unmeasurable dark.
: While primarily a planetarium software, Stellarium includes a powerful "Oculars" plugin. It simulates the exact view through your optics and sensor, though users must be careful to input correct chip dimensions to avoid scale errors. astro fov calculator 2021