| Gap |
| Slit |
| Hole |
| Vent |
| Crack |
| Orifice |
| Opening |
| Lens part |
| Lens feature |
| Lens opening |
| Light setting |
| Light limiter |
| Camera setting |
| Camera feature |
| Camera opening |
| Olympus opening |
| Optical opening |
| Telescope opening |
| Camera-lens opening |
| Photographer's setting |
| What a camera's f-stop sets |
| What changing the f-stop changes |
| Device controlling amount of light admitted |