About
The Astro Manual is a set of free calculators and guides for people who photograph the night sky.
Why it exists
Most astrophotography questions come down to a handful of numbers. How long should each sub be? Will these spacers put the sensor in the right place? How long can I expose on a tripod? Which nights this month are dark, and what is up? The answers are usually scattered across forum threads, spreadsheets and rules of thumb that no longer hold for modern cameras. This site puts each calculation in one place, shows the method behind it, and lets you run it for your own gear and location.
What is here
- Six tools: an imaging planner, an exposure calculator, a dark sky calendar, an untracked exposure calculator, a back focus calculator and a dew point calculator.
- A target guide covering 272 galaxies, nebulae and clusters, with the best months to photograph each from northern and southern latitudes.
- 4 written guides that explain the ideas behind the tools with worked examples.
- A new moon calendar, monthly target lists and a daily quiz.
How it is built
Every calculation runs in your browser. Nothing you enter is sent anywhere, and gear profiles you save stay on your device. There are no accounts and no sign-ups.
Accuracy comes first. A tool only goes on the site when its results can be checked against a published source, and an earlier field-of-view tool was removed because its results could not be. The sources and checks for every tool are listed on the methods page.
How the site is paid for
The tools are free. Some pages show retailer links for gear that suits the numbers on that page, and the site earns a commission if you buy through them. Recommendations come from the calculations, not from the retailers. Details are in the affiliate disclosure.
Corrections and suggestions
If a number looks wrong, or you would like a tool that is not here, write to info@theastromanual.com. Corrections are checked and fixed, and the methods page is updated when a method changes.