When to Use This Cheat Sheet
Use this when you are shooting the night sky far from city lights. Astrophotography has zero margin for guessing; these settings keep stars as points and noise under control.
Quick Settings Reference
The table covers nine astro scenarios. The 500 rule (500 / focal length = max shutter seconds before star trailing) is your starting formula. For APS-C sensors, divide by effective focal length (focal length x crop factor).
Key Principles
- The 500 rule sets your shutter ceiling. Exceed it and stars become short streaks. For pixel-peepers, the NPF rule is tighter but the 500 rule is reliable in the field.
- Widest aperture, always. f/1.4 or f/2.8 lets in the most starlight. Coma (smeared corner stars) is a tradeoff; correct in post or accept it.
- ISO 3200 is the typical sweet spot. Higher adds noise without capturing more photons on most sensors. Some cameras perform well at 6400. Test yours.
- Manual everything. Autofocus cannot lock on stars. Use live view zoomed to 10x on a bright star, then manually focus until it is the smallest point.
- Stacking reduces noise dramatically. Shoot 10-20 identical frames, then average them in Sequator or DeepSkyStacker. Noise drops by the square root of the frame count.
Adjustment Tips
- Focus on a bright star or distant light at infinity, then tape the focus ring so it does not shift.
- Use an intervalometer for hands-free shooting. Set a 1-second gap between frames for buffer clearing.
- Shoot during a new moon. Even a quarter moon washes out faint nebulae and the Milky Way core.
- A star tracker mount lets you expose for 2-4 minutes at low ISO, dramatically improving signal-to-noise.
Common Traps
- Leaving autofocus on and getting completely out-of-focus star fields.
- Shooting from a backyard near city lights and wondering why the sky is orange.
- Using a kit lens at f/3.5 and expecting Milky Way detail; fast glass is essential.
- Forgetting to disable long-exposure noise reduction, which halves your shooting time with dark frames.
ShutterCoach Connection
Upload your astro image to ShutterCoach for feedback on star sharpness, noise levels, and Milky Way detail.