Mirrors play a crucial role in certain types of cameras, primarily enabling photographers to see exactly what the lens sees before taking a picture.
In DSLR (Digital Single-Lens Reflex) cameras, a key component is the reflex mirror. This mirror is essential for the camera's optical viewfinder (OVF) system.
The Role of the Reflex Mirror
- Position: The reflex mirror is situated directly behind the camera's lens.
- Angle: It sits at a 45° angle.
- Function: Its primary job is to reflect the light that passes through the lens upwards into the camera's OVF.
- Mechanism: The majority of DSLRs feature a moving reflex mirror. This mirror flips up out of the light path just before the photo is taken, allowing the light to hit the image sensor.
How it Works in Practice
When you look through the viewfinder of a DSLR, you are seeing the light that has traveled through the lens, hit the reflex mirror, been bounced upwards, often passed through a pentaprism or pentamirror (which corrects the image orientation), and finally reached your eye.
This system provides a true "through-the-lens" view, which is a significant advantage for precise composition, especially with interchangeable lenses.
In summary, in DSLR cameras, a specifically positioned mirror redirects light from the lens to the viewfinder, allowing the photographer to frame the shot.
