Datasheet

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■ BRIDGING THE FILM/DIGITAL GAP
Figure 1.2: In a typical sensor, red, green, or blue filters cover individual pixels (photo-
receptors) in a tiled mosaic pattern (left). The filters allow one wavelength of light to pass,
and a given pixel therefore records only one color (right).
The processing of the digital data from the sensor is the most complex part of the
process, and also the most variable. Unless you’ve chosen to save the image in the RAW
file format, the camera’s onboard processor will organize the separate R, G, and B pixel
values into RGB data and perform a variety of other steps before assembling the final
image. This processing may include compression (in the JPEG file format) or no compres-
sion (in the TIF file format). You’ll learn more about these formats in subsequent chapters.
After light is captured by the sensors and the processing is complete, the infor-
mation (data) is passed on in digital form to some sort of built-in memory system or,
more commonly, to an external storage medium such as the commonly used Smart
Digital (SD), xD-Picture Card, or CompactFlash (CF) card.
The sensor and electronic system that carry out the task of digital processing and
storage are built entirely into the camera and cannot be easily swapped and upgraded.
By comparison, film has individual characteristics dependent on brand and manufactur-
er, and those characteristics are independent of the camera itself. You can easily switch
from a fine-grained film to a fast, grainy one by simply replacing one roll with another
in the camera.
Comparing Resolution
Film resolution, expressed as resolving power, is a function of the size and structure of
the silver halide particles (Fine, Medium, or Coarse), the emulsion thickness, and the
actual size of the film (35mm, 120mm, etc.). Digital camera resolution is based on the
number of pixels contained in a particular sensor. The number of pixels is expressed
either as an “A
× B” form with “A” representing the number of pixels in the width and
“B” the number of pixels in the height of a sensor (for example, 2576
× 1932 pixels) or
as a total number of pixels (for example, 4,976,832 pixels, or more simply, 5.0
megapixels).
In general, the more pixels a sensor is capable of capturing, the finer the detail
that is recorded. I must qualify this statement, though, because there are some sensors
on the market—notably ones created by Foveon and Fuji—that squeeze more color
data from each pixel, thereby making a side-by-side, pixel-to-pixel comparison between
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