Observation

This question was not popular among the candidates and most of the candidates that attempted it responded poorly by giving the dictionary meaning of exposure. Such poor responses made those candidates to lose a major chunk of the obtainable marks. The following are some of the responses expected from candidates:

• Exposure

-           It is the amount of light received by photographic emulsion on the film or the digital censor.
-           It is the product of the intensity of light plus the duration of its intensity
-           It is the appropriate control of light using aperture and shutter speed in a camera to produce an image.

•       Exposure is largely determined by the aperture and shutter speed which

control the amount and duration of light allowed into the camera.

(b)        (i)         Aperture
-           It is the circular opening within a lens that determines the amount of
light that is allowed to reach the film or sensor.
-           It has different size openings known as “f-stops” engraved on the
barrel of lens i.e. f2.8, f5.6, f8, f11, etc.
-           It is used to determine the overall sharpness in a picture (depth of field) using any aperture from f8 – f22
-           Moving the aperture ring clockwise (for example from f4 to f5.6) decreases the amount of light while moving from f4 to f28 increases the amount of light.

                        (ii)        Shutter Speed
-           It determines the length of time light is allowed to stay in the camera during exposure.
-           It is used to “freeze” action by capturing a fast moving object using fast speed like 1/500.
-           It can be used to make an image appear blurred using slow speed like 1/30
-           The faster the shutter speed, the sharper the moving image will appear.
-           It can open for a fraction of a second or for a longer time.
-           Its settings are in seconds or fractions of a second ½ sec, ¼ sec, 1/8
sec, 1/15 sec, 1/30 sec, 1/60 sec, 1/125 sec, 1/250 sec, 1/500, 1/1000 sec. Each setting lets in twice as much light as the next faster setting.

                        (ii)        Film Speed (ISO)
-           It is the degree of film sensitivity/ digital sensor to the controlled light.
-           ISO means International Standard Organization.
-           Films are categorized as slow, medium and fast: ISO 100 is slow, ISO 200 is medium, while ISO 400 and above are fast.
-           Common film ratings are ISO 100, ISO 200 ISO 400, ISO 800, ISO 1600 and ISO 3200
-           A film speed is measured using ratings such as ISO
-           Allows photographer select the appropriate film for specific photographic situation/assignment.

•   Slow speed films are ideal for portraiture while fast films are used for action situations like sporting events for freezing a moment/subject.

•   Film speed determines the extent to which an image can be enlarged in print without losing sharpness.