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8.1 To describe the components and the operating features of a normal camera lens. (COM)
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Most 35mm cameras come equipped with a 50mm lens, referred to as a normal lens. The view provided by this lens is close to what the human eye sees.
Operating features include focus control and aperture control.
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8.2 To understand the term speed as it refers to a camera lens. (COM)
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A lens's aperture is the determining factor in lens speed. A lens that is faster than another opens wider to admit more light. For example, a lens with a minimum aperture of f /2.8 will be faster than a lens with a minimum aperture of f /4. The fastest lenses are close to f /1 (f /1.2).
Some lenses with larger lens diameters will allow more light to enter the lens and thus compensate for the longer lens barrel. The cost of a lens will increase dramatically as the diameter and focal length of the lens increases.
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8.3 To differentiate between fixed focal length and zoom lenses. (CCT)
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Have students compare the two styles of lenses regarding the field of view that each type of lens offers.
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8.4 To compare the advantages and disadvantages of fixed focal length and zoom lenses. (CCT)
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Students should include the following in their list: weight, cost, focal length, field of view and lens speed.
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8.5 To compare the characteristics of a fixed focal length lens with those of a zoom lens. (CCT)
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Include wide angle, normal, and telephoto styles of lenses for comparison. See the bibliography for information sources.
Some zoom lenses have macro capabilities for close-up magnification work and their use should be discussed here.
Zoom lenses also offer creative potential not available with a fixed focal length that could be explored through a photographic assignment.
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8.6 To understand the different uses of coloured lens filters.
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This type of filter attaches to the end of the camera lens and is used for creating a variety of special effects with colour film.
When coloured filters are used with black and white film different results are achieved. Contrast or tone may be altered in a black and white photograph to make the result more appealing.
Have students take photographs of the same object with and without a filter and compare the results.
Consider using the following types of filters, polarizing, ultra-violet (UV), contrast and tone changing (red, yellow and orange, blue and green).
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8.7 To list the types and uses of colourless or clear filters. (COM)
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These filters may be used with all types of film. Have students include: ultra-violet, skylight (1A), polarizing, haze, neutral density, diffusion, special effects and other filters in their research.
The UV and 1A filters are frequently used to protect lenses from accidental damage by acting as a safety barrier on the front of the lens.
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8.8 To explore the variety of special effect lenses that are available and list their characteristics. (TL, COM)
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Accessory manufacturers make a wide variety of filters for special situations.
More information is available about filters in the bibliography.
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8.9 To describe the effect of close-focusing attachments. (COM)
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Extension tubes, bellows, macro lens, microscope attachments and close-up lenses are methods used for photomacrography.
Students can calculate the reproduction ratio that determines the magnification for a specific subject they want to use. See the bibliography for further information.
Have students produce images from one location using close-up lenses. Close-up lenses are the least expensive alternative when selecting a method to meet this objective. If obtaining close-up lenses is not possible, have students look at images created using this equipment.
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