This is the home for Stellar Nomads’ free astrophotography calculators and telescope tools — six browser-based calculators that take the guesswork out of planning a deep-sky imaging session, from framing your target to dialling in focus and guiding. Every tool is free, needs no sign-up, and runs entirely in your browser.
Quick answer: Stellar Nomads offers six free astrophotography calculators: a field of view simulator, an all-in-one astrophotography calculator, a sub-exposure calculator, an integration-time calculator, a critical focus zone calculator, and an autoguider settings calculator. Together they cover framing, sampling, exposure, focus, and guiding.
Framing and target planning
Telescope Field of View Calculator
See exactly what your telescope, camera, or eyepiece will frame against real deep-sky survey imagery before you set up. Pick your gear and a target to preview the true field of view, framing, and orientation. It is the fastest way to know whether the Andromeda Galaxy or the Orion Nebula will fit your sensor.
Astrophotography Calculator
The all-in-one tool for pixel scale, field of view, signal-to-noise, drizzle suitability, and the critical focus zone in a single place. Use it to check whether your imaging train is well sampled for your sky conditions and to compare different camera-and-telescope combinations.
Exposure and integration
Sub-Exposure Calculator
Find the ideal length for each individual frame — long enough to swamp your camera’s read noise, short enough to protect star colour and avoid wasted subs. Enter your sky brightness, camera, and filter to get the sub-exposure that maximises signal-to-noise.
Integration Time Calculator
Plan how much total exposure a target needs and how to spread it across nights. It turns a target and a sky into a realistic schedule, so you know whether a faint galaxy needs two hours or twenty.
Focus and guiding
Critical Focus Zone Calculator
Work out the depth of focus for your telescope using the modern New Critical Focus Zone (NCFZ) formula, so you know exactly how precise your focus must be for pin-sharp stars. Faster scopes have a tiny focus tolerance — this tells you how tiny.
Autoguider Settings Calculator
Get your guide scale, a recommended PHD2 minimum-move, and the right calibration step from your guide scope and camera. It is the quickest way to start a guiding session with sensible settings instead of guessing.
How the calculators work together
A typical imaging session flows through these tools in order. First, use the field of view simulator to choose and frame a target. Next, the astrophotography calculator confirms your sampling and pixel scale. Then the sub-exposure calculator and integration-time calculator set your exposure plan. On the night, the critical focus zone calculator and autoguider calculator help you achieve sharp focus and tight tracking.
For the targets themselves, browse our solar system guides and the planets, or read the astrophotography fundamentals guide to see how these numbers fit together.
Frequently asked questions
Are the Stellar Nomads calculators free?
Yes. All six astrophotography calculators are completely free, require no sign-up, and run entirely in your browser with nothing to install.
Which calculator should I start with?
Start with the field of view simulator to frame a target, then the astrophotography calculator to check sampling. The exposure, focus, and guiding tools come into play as you plan and run the session.
Do the calculators work on mobile?
Yes. Every tool is browser-based and works on phones, tablets, and desktops, so you can plan a session from anywhere.
What information do I need to use them?
Mostly your telescope focal length and aperture, your camera sensor size, pixel size and read noise, and your sky brightness or Bortle class. Each tool explains the inputs it needs.
