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QUESTION: I have used a
regular camera for years and now think I might like to try out a digital
camera. I am confused as to how they work. If they don’t use film to make
the pictures what do they use?
ANSWER: Both film based
cameras and digital cameras use lenses to create images on sensitive
surfaces. The two types of cameras differ greatly on how the images are
captured and stored.
A film picture is taken when the image of the
picture is captured in physical form on the film using a camera. That
physical image is made visible and somewhat permanent by chemical
development. This is what is called a negative if print film is used. The
negative is used by the film processor to make another image called the
print.
A digital camera, just like a film camera, causes a focused
image to appear on a light sensitive surface. And just like a film camera
it captures information about the image in a brief period of time. But
instead of the light sensitive surface being a movable piece of film the
surface is a physically permanent piece of light sensitive semiconductor
material. To my knowledge this surface, called the sensor, is able to
capture image information without loss of efficiency until something else
on the camera breaks or wears out.
After the picture is taken in a
film camera the piece of film containing the image information is moved
and new film is put in its place. In a digital camera the image
information captured by the sensor is used to create an electronic file.
This file contains density and color values for all the points or picture
elements in the image. The greatest number of picture elements, often
shortened to pixels, that the camera sensor can capture is known as its
resolution. These picture elements are usually counted by the million.
Therefore a 4.0 megapixel camera means that the camera will capture an
image with four million picture elements when the camera is set to its
highest resolution.
The picture file is then usually stored on a
memory card. The memory card might be considered the electronic equivalent
of film although, unlike film, the picture files on the card can be
transferred electronically to another place. Once this is done the
pictures on the card can be thrown away so that the card is empty and
ready for use again. All memory cards work the same way and currently
there are several different types with no one type of card being
predominant. Memory cards come in different memory sizes. This will be
discussed in another Photo Talk.
Check MarshallsCamera.com for photo
class information.
Copyright 2004 by Marshall Ledbetter
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