Digital SLR Show Time!
The second century of photography demands new principles and possibilities for regular renovations. The era of digital single-lens reflex photo camerasdictates the following design principles:
1. Reflex mirror
2. 4-element lens
3. Pentaprism
4. Image sensor
5. Matte focusing screen
6. Condenser lens
7. Focal-plane shutter
8. Eyepiece
The operation process of a DSLR is: the mirror glints the light through the lens upwards at right angle. The light is then three times reflected by the roof pentaprism, and directed just for the eye of photographer. During snapshot, the mirror assemblage swings upward, the aperture shrinks, a shutter opens fast and projects light onto the image sensor. A second shutter then covers the sensor, the shutter resets and the mirror lowers. The period when the mirror makes a break is called the “viewfinder blackout”.
The qualitative advantages of the DSLR are:
• The operation speed is measured in milliseconds and can be repeated for 3–9 times per second;
• DSLR’s sensor is very close in size to the film format;
• a great amount of interchangeable lenses;
• DSLR allow a preview of framing up to the exposure moment;
• possibility of previewing the depth of field;
• the camera’s screen can be also used as a viewfinder.