Example
Input: 24mm
Result: 20s max
What is Star Trail / NPF Rule?
500 Rule or NPF.
How it Works
500 / Focal Length.
FAQ
500 Rule?
Simplified formula.
NPF Rule?
More accurate for high megapixel.
Crop sensor?
Use equivalent focal length.
Trails?
Exceed this time to get trails.
ISO?
High (1600-3200).