The above cutaway diagram of a Sony DSC-S70, introduced in 2000, shows the typical characteristics of a digital camera. Images are stored on a removable memory card, in this case Sony s proprietary memory stick on the left of the diagram. The half removed lithium battery powers the camera for up to 2.5 hours. Camera Shutters Back to the top Most single lens reflex cameras use a focal plane shutter to control the amount of light falling on the film. The shutter consists of metal blinds that form a slit which, when passing across the face of the film, creates the exposure.
Exposure duration is controlled by the slit width and the speed of the blinds.
This type of shutter offers a wide speed range and also enables the 'reflex' camera mechanism to be fitted behind the lens. Click here to take a picture with a Focal Plane shutter Electronic flash imposes problems because of its short duration, if fired when the slit is travelling the flash will only expose the small potion of the negative revealed by the slit. Flash synchronisation is only possible at slow speeds where the gap between the blinds is so great that at one point, the point of synchronisation, the complete film plane is uncovered. Click here to take a flash picture with a slow shutter speed Focal plane shutters may create image distortion if the subject is rapidliy moving across the field of view or the camera is being moved to track the subject. In the time it takes for the slit to move across the film plane the subject has moved.