Calculadora de Regra de Exposição de Câmera — Formula
## Astrophotography Exposure Rules
### 500 Rule (simple)
**t = 500 / f** seconds (f = focal length in mm)
Stars will begin to trail after this time on an untracked mount with a full-frame sensor.
### NPF Rule (more accurate)
Accounts for pixel pitch and is better for modern high-resolution sensors. A shorter exposure may be needed for sharp pinpoint stars.
### 500 Rule (simple)
**t = 500 / f** seconds (f = focal length in mm)
Stars will begin to trail after this time on an untracked mount with a full-frame sensor.
### NPF Rule (more accurate)
Accounts for pixel pitch and is better for modern high-resolution sensors. A shorter exposure may be needed for sharp pinpoint stars.
Exemplo Resolvido
50 mm lens with 4.3 µm pixel pitch.
- 500 Rule: 500 / 50 = 10 seconds
- Stars trail after about 10 seconds at 50 mm.
- For crop sensors, divide by the crop factor (e.g., 1.5).