Getting your camera settings right is one of the most important steps in astrophotography. Too little exposure and your images will be noisy and lacking in detail; too much and your stars will trail, your highlights will clip, and your data will be unusable. A full spectrum camera gives you a significant advantage over a standard camera for deep-sky work — but you still need to dial in the right settings to get the best out of it. This guide covers everything you need to know. For background on why a full spectrum camera is better for astrophotography, read: Why a Full Spectrum Camera is Better for Astrophotography Than a Standard Camera.
Before You Start — Essential Preparation
Good astrophotography starts before you touch the camera settings. A few things to sort out first:
- Let your camera acclimatise — bring your camera outside at least 30 minutes before you start shooting. Temperature changes cause the sensor to produce more thermal noise, and a camera that has acclimatised to the ambient temperature will produce cleaner images.
- Charge your batteries — cold nights drain batteries faster than normal. Carry at least two fully charged spares.
- Format your memory cards — RAW astrophotography files are large. Make sure you have plenty of space.
- Disable long exposure noise reduction — in-camera long exposure noise reduction takes a dark frame after each exposure, effectively halving your imaging time. Disable it and take dark frames separately as part of your calibration frame workflow.
- Disable image stabilisation — if your camera or lens has optical image stabilisation, turn it off when shooting on a tripod. IS systems can introduce micro-vibrations when the camera is stationary.
Shoot in RAW
This is non-negotiable for serious astrophotography. RAW files contain the full data captured by the sensor, giving you maximum flexibility in post-processing and stacking. JPEG files are processed in-camera, compressed, and discard a significant amount of data — data that is essential for extracting faint nebula detail from your images. Always shoot RAW.
ISO Settings
ISO is one of the most debated settings in astrophotography, and the right value depends on your camera, your sky conditions, and your target.
Recommended Starting Points
- Full-frame cameras (Sony A7 series, Nikon Z, Canon R) — ISO 1600–3200 is a good starting range for most deep-sky targets under dark skies. Under light-polluted skies, lower ISO (800–1600) may be preferable to avoid clipping the sky background.
- APS-C cameras — ISO 800–1600 is typically a good starting point.
- Sony A7S series — The exceptional low-light performance of the A7S allows effective use at ISO 6400 and above, making it outstanding for very faint targets or very short exposures.
Shutter Speed — The 500 Rule and Tracking
Stars move across the sky as the Earth rotates. If your shutter speed is too long, stars will trail — appearing as short lines rather than points of light. The maximum shutter speed before trailing becomes visible depends on your focal length and sensor size.
The 500 Rule (Untracked)
For untracked shooting on a static tripod, the 500 Rule gives you a rough maximum shutter speed before star trailing becomes visible:
Maximum shutter speed (seconds) = 500 ÷ (focal length × crop factor)
For example, with a 20mm lens on a full-frame camera: 500 ÷ 20 = approximately 25 seconds. With a 20mm lens on an APS-C camera (crop factor 1.5): 500 ÷ (20 × 1.5) = approximately 17 seconds.
With a Star Tracker
A star tracker — a motorised mount that rotates to compensate for the Earth's rotation — removes the trailing limitation entirely, allowing exposures of several minutes or more. With a tracker, shutter speed is determined by sky brightness (light pollution) and target brightness rather than trailing concerns. Exposures of 2–5 minutes per frame are common with a tracker under dark skies.
For serious deep-sky work, a star tracker is a transformative addition to your kit. Even a basic tracker like the Sky-Watcher Star Adventurer or iOptron SkyGuider Pro dramatically increases what you can capture.
Aperture
For astrophotography, you generally want to shoot at or near your lens's widest aperture to maximise light gathering. However, most lenses are not at their sharpest wide open — stars at the corners of the frame may appear elongated or distorted at maximum aperture due to optical aberrations such as coma and astigmatism.
A common approach is to stop down one stop from maximum aperture — so f/2.8 on an f/2 lens, or f/2 on an f/1.8 lens. This typically gives a significant improvement in star shape at the corners while retaining most of the light-gathering advantage of a fast lens. For advice on choosing the right lenses, read: The Best Lenses for Astrophotography with a Full Spectrum Camera.
Focus
Achieving precise focus on stars is one of the most challenging aspects of astrophotography, and it's critical — even slightly soft focus will significantly degrade your images.
- Use live view at maximum magnification — zoom in to 10x magnification on a bright star and adjust focus until the star is as small and sharp as possible
- Use a Bahtinov mask — a diffraction mask that fits over the lens and produces a distinctive spike pattern that makes precise focus easy to achieve. Highly recommended for serious astrophotography.
- Switch to manual focus once focused — and tape the focus ring in place to prevent accidental movement during the session
- Recheck focus periodically — temperature changes during the night can cause focus to shift, particularly with metal-barrelled lenses
Using an Intervalometer
An intervalometer is a device — either a dedicated remote or a function built into many cameras — that automatically triggers the shutter at set intervals, allowing you to capture a series of exposures without touching the camera. For astrophotography, it's an essential tool.
Intervalometer Settings
- Delay: 2 seconds (allows any vibration from pressing the start button to settle)
- Exposure: your chosen shutter speed (e.g. 20 seconds for untracked, 2–5 minutes for tracked)
- Interval: exposure time plus 1–2 seconds (to allow the camera to write the file before the next exposure begins)
- Number of frames: as many as your session allows — more frames means better stacking results
Calibration Frames
Professional astrophotography involves capturing not just your main "light" frames but also calibration frames that are used in post-processing to remove noise and artefacts:
- Dark frames — exposures taken with the lens cap on, at the same ISO, shutter speed, and temperature as your light frames. Used to subtract thermal noise from your images.
- Flat frames — exposures of an evenly lit surface used to correct for vignetting and dust spots on the sensor.
- Bias frames — very short exposures with the lens cap on, used to measure the base read noise of the sensor.
Capturing calibration frames adds time to your workflow but significantly improves the quality of your final stacked image. For a full guide to stacking your frames, read: How to Stack Astrophotography Images — A Beginner's Guide.
A Quick Reference Settings Guide
- Format: RAW
- ISO: 1600–3200 (full-frame), 800–1600 (APS-C)
- Shutter speed: 15–25 seconds (untracked), 2–5 minutes (tracked)
- Aperture: one stop down from maximum (e.g. f/2 on an f/1.8 lens)
- White balance: daylight or manual — colour balance is corrected in post-processing
- Long exposure NR: OFF
- Image stabilisation: OFF
- Focus: manual, set on a bright star using live view at maximum magnification
- Intervalometer: 2 second delay, consistent exposure time, 1–2 second gap between frames
These are starting points — every camera, lens, location, and target is different, and developing your own workflow through experimentation is part of the journey. The key is to capture as many frames as your session allows, keep notes on your settings, and review your results carefully to refine your approach over time.
Explore our range of full spectrum converted cameras to find the right body for your astrophotography setup.