Equipment
焦比
Focal ratio
Focal length divided by aperture; f/5 is faster than f/10.
Nebulae like f/4–f/5; planets like f/10 and slower.
Related terms
- Tripod — The base holding a telescope or camera.
- Binoculars — Two short scopes side by side: wide field, easy to aim.
- Exposure — How long a camera sensor collects light.
- Tracking — Moving the gear with the sky so stars stay round.