Star Trails
Camera Sensor
Lens Settings
Calculation Method
Target Declination
Stars near celestial poles move slower, allowing longer exposures
Stacking Parameters
Light Pollution (Bortle Scale)
Light domes visible
Planning Date
Point Stars (No Trailing)
Recommended Max
14s
NPF Rule500 Rule
25s
Less accurate400 Rule
20s
ConservativeAt 0° Dec
14s
AdjustedStar Trail Preview
Trail Arc Length
14.9°
Total Shots
112
Storage Needed
~2.8 GB
Trail Length Reference
| Duration | Arc Length | Effect |
|---|---|---|
| 30m | 7.5° | Subtle streaks |
| 2h | 30° | Clear arcs |
| 4h | 60° | Dramatic circles |
| 24h | 360° | Full circle |
Stacking Calculation
Total Shots
112
Actual Duration
59m 44s
Trail Arc
14.9°
Storage
~2.8 GB
Intervalometer Settings
- Interval: 32 seconds
- Exposure: 30 seconds
- Shots: 112 (or unlimited)
- Delay: 2-5 seconds recommended
Stacking Tips
- Use "Lighten" or "Maximum" blend mode in your software
- Recommended software: StarStaX (free), Photoshop, Sequator
- Keep intervals short (1-2s) to avoid gaps in trails
- Shoot in RAW for best stacking results
- Consider gap-filling algorithms for smoother trails
Shooting Conditions for
Recommended ISO
1131
Bortle 4Crop Factor
1×
Pixel Pitch
5.9µm
Understanding the Rules
- 500 Rule: Simple but often produces slight trailing on high-res sensors
- NPF Rule: More accurate - accounts for aperture and pixel density
- Declination: Stars near celestial poles (Polaris) move slower
- Star rotation: 15° per hour (360° in 24 hours)
Astrophotography Tips
- Use the widest aperture available (f/1.4-f/2.8 ideal)
- Set ISO based on light pollution conditions
- Use manual focus set to infinity (∞) and fine-tune on a bright star
- Shoot in RAW for better post-processing flexibility
- Consider a star tracker for longer exposures without trailing
- Check moon phase - new moon is ideal for Milky Way shots