Chapter 6 - Digital cameras

Abstract

This chapter concentrates on the practical differences between digital and film cameras— differences in cost and design; the way the picture is stored and retrieved; and what to expect in terms of image quality. Digital cameras don't use film, otherwise many of their features—viewfinder, image-forming lens, aperture, flash—are the same or are closely related to film-based equipment. In fact most “top-end” digital camera makers such as Nikon and Canon have made use of their host 35 mm SLR bodies for their range of digital cameras. Others take the form of a digital array sensor contained in a back replacing the detachable film magazine on a medium format SLR camera or the film holder on a view camera. Instead of film a digital camera has a CCD (charge-couple device) or a CMOS (complementary metal-oxide semiconductor) sensor, which consists of a grid of phototransistors to sense the intensity of the light across the plane of focus. CMOS sensors are slightly different from CCD sensors in that they generally use less power and have a different kind of light-sensing material. When one shoots on film they can choose between two different types: daylight or tungsten-balanced film. When shooting digitally the white balance (i.e. color temperature) of the image is normally calculated automatically by the camera. The sensors found in most digital cameras are much smaller than a 35 mm frame, some as tiny as 7 × 5 mm. Different file formats such as TIFF (Tagged Image File Format), RAW, and JPEG (Joint Photographic Experts Group) are explored.