Astrophotography Reference — FocalMath
Twelve field-reference guides on photographing the night sky, distinct from the Astro 500/NPF Calculator itself — these pages cover the surrounding decisions a shutter-speed number alone doesn't answer: how to plan a Milky Way shoot around the calendar and the moon, how to actually focus a lens in the dark, where light pollution genuinely ends and how to find a dark-sky location, what makes a lens suited to astrophotography in the first place, and how star trackers and image stacking change the calculation entirely.
A bright moon washes out the Milky Way almost completely, so planning around lunar phase is one of the first things a real astro shoot depends on — for the moon phase and lunar calendar itself, our sister site MoonCadence covers exactly that in depth.
How This Section Relates to the Astro Calculator
The Astro 500/NPF Rule Calculator answers one specific, narrow question well: given your camera and lens, how long can the shutter stay open before star trailing becomes visible? That's genuinely important, but it's one input into a much larger set of decisions a real night-sky shoot depends on — where to go, when to go, how to focus a lens that autofocus can't handle in the dark, and what to do once you're back at a computer with a folder of RAW files. These twelve pages cover that surrounding decision-making, each focused on one specific part of the process rather than trying to be a single do-everything guide.
Where to Start
If you've never photographed the night sky before, How to Photograph the Milky Way is the complete field walkthrough — timing, location, gear, focus and exposure in the order they actually matter. From there, the more specialized pages (star trails, aurora, meteor showers, moon photography) each adapt the same core principles to a specific subject with its own particular quirks. Once you're comfortable with the basics, the star-tracker and image-stacking pages cover the next tier of equipment and technique for photographers ready to push past what a stationary tripod alone can achieve.
Every page here assumes you already have the shutter-speed math handled by the Astro 500/NPF Rule Calculator and focuses purely on the surrounding decisions — none of them repeat the calculator's own formula explanation, which lives on the tool page and in the matching guide, kept separate on purpose so each page stays focused and easy to skim in the field.