# Astrophotography Exposure Calculator

> The exposure calculator estimates equivalent imaging time under different light pollution conditions.

Light pollution raises the sky background and reduces the signal-to-noise ratio for faint astronomical targets. Light Pollution Map includes an exposure calculator so astrophotographers can compare how much longer an exposure may need to be when moving from dark skies to brighter skies.

## Inputs

- Bortle class or SQM value for the target location.
- Reference exposure time from a darker baseline.
- Current location data when available from the map.

## How To Use The Result

Treat the result as a planning estimate, not a replacement for test exposures. Camera sensor behavior, filters, optics, target altitude, moonlight, haze, and local lighting can all change the final exposure strategy.

## Related URLs

- Map: https://lightpollutionmap.app/
- Stargazing Hub App: https://apps.apple.com/cn/app/id1478601599