Body and Functions of a Single-Lens Reflex Camera

The two following images allow us to glimpse the inside of a digital single-lens reflex camera. Image 1 illustrates how the incident light hits the mirror through the lens and is then redirected to the viewfinder.

Vor der Belichtung - Beispiel: Digitale SLR-Kamera Canon EOS 500D [Abbildung: Canon]


During exposure, the mirror flips upwards (Image 2). The shutter behind the mirror is released for light exposure. As the mirror flips upwards, there is a more or less audible click depending on the model. The mirror is also flipped upwards in live view mode or during a video recording. During this phase, the viewfinder is covered by the mirror. Some cameras have a fixed, semi-transparent mirror that doesn't move while the photo is being taken. This enables virtually silent image capturing; a fast burst mode and a fast auto focus (e.g. Sony Alpha 55). It remains to be seen whether or not this technology in digital single-lens reflex cameras will prevail.


Während der Belichtung bzw. im Live-View- oder Video-Modus : Beispiel: Digitale SLR-Kamera Canon EOS 500D [Abbildung: Canon]



The mirror of an autofocus SLR camera isn't just used for the viewfinder. These cameras use the mirror for focussing. This is not possible in live view mode: the camera electronics has to use the contrast sensitivity captured by the light detected by the sensor. By doing so, the camera's focus is generally very restricted. Tip: If you require a fast auto focus, use the viewfinder even if you have live view.



Analog single-lens reflex camera

Image 3 shows one of the classic analog single-lens reflex cameras, the Olympus OM2. By looking at the illustration you can see that the same construction principles are used in analog and digital single-lens reflex cameras.

Digital single-lens reflex camera technology differs from analog photography in that it is much simpler to capture, edit and save images.


Beispiel: Analoge SLR-Kamera Olympus OM2 [Abbildung: Olympus]