into silver metal when exposed to light. Through a complicated process,
called photofinishing or photo development, the image is converted to an
image on special paper. Black-and-white film consists of a single layer of
silver compounds while color film consists of three layers, each sensitive
only to blue, red, or green light. By combining different amounts of blue,
red, and green, any color may be produced as shown in Figure 7. Note
that white is produced when all three colors are at full brightness and black
is produced when all three have no brightness (no light is present). The
same idea is used in your color TV set. Turn on your TV and look at it very
closely with a magnifying glass (if you don’t have a magnifying glass then
place your AK-540 camera against your TV and look through the
viewfinder). You will see that your entire TV screen consists of blue, red,
and green dots of varying brightness.
Film remains sensitive after it is first exposed to light and must be kept in
darkness until photofinishing is complete. For this reason, photofinishing
work is done in a room called a “darkroom”. In very unusual situations,
such as for special effects in the movies, a second exposure is used. If done correctly, this may be used to give
the appearance of ghosts. “Time-lapse” photography uses many exposures spread over a long time or one
continuous exposure (with the background and light conditions the same) to show how something moves. This
could be used to show the growth of a plant.
The light-sensitivity of the silver compounds can be varied. This is called the film “speed” or the ASA (American
Standards Association) rating. (The ISO, for International Standards Organization, rating is also used and is the
same as the ASA scale). Slower speeds, such as ASA 100 or lower, are less sensitive to light and have the
advantages of giving more detailed pictures (very important if you plan to make big enlargements), can use
slower shutter speeds, and are less expensive. Faster speeds, such as ASA 400 or higher, are more sensitive
to light. They have the advantage of requiring less light and can use faster shutter speeds. This is very
important for action shots where the subject is moving. The more the subject moves while the shutter is open,
the more blurred the final picture will be. Your AK-540, as with most point and shoot cameras, works with speeds
of ASA 100, 200, or 400 (400 is preferred).
The most common problem with taking good pictures is difficult light conditions. Even the best cameras have
a harder time with lighting than your eyes do. Pictures of people come out best with normal daylight, but
sunshine, shade, sun glare, bright colors, dark colors, and house lights make things difficult. Movie studios,
television studios, and concert halls have bright lights to ensure good results. Pictures of sunrises and sunsets
are challenging because the sky is bright while the ground is very dark.
You now know three ways to take good pictures in low light: larger aperture, faster lens shutter speed, and faster
film speed. Unfortunately, only advanced cameras allow you to change aperture size or shutter speed, and you
can only have one speed of film in your camera at a time. However, since most simple cameras are used to
take pictures of people at close distances, the “flash” feature was developed. Flash cameras produce a burst
of light (the “flash”) towards the subject just before the picture is taken. This makes sure that the subject (usually
people) has enough light to photograph well.
Mechanical Operation of the AK-540:
(This section is easier to understand if you read it after building the camera.) Turning the film advance knob A9
turns film advance A1 which has tabs that pull the film out of its cartridge. The “teeth” on the lower section of
the film advance knob interlock with those on film holder shaft A6, turning it and film holder A4, which wraps up
the exposed film. The small tab at the top of film advance shaft A3 advances the film counter (part of B2) one
count for each picture taken. After turning once around, the film advance knob A9 has a tab which locks on
shutter control B1 until a picture is taken. Advancing the film also stretches spring B4, which is attached to B1.
When the shutter button is pressed to take a picture, stretched spring B4 is released moving shutter control B1
back to the side of the camera. Part of B1 extends downward and catches briefly on lens shutter D1, opening
it briefly and exposing the film. The movement of B1 also releases the lock between it and film advance knob
A9, so the film may be advanced for the next shot.
MAGENTA
CYAN
WHITE
GREEN
YELLOW
RED
BLUE
Figure 7
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