29th May 2008
More expensive cameras can have magnesium alloy, aluminium alloy,or titanium shells that are covered with polycarbonate - a composite material structure. An alternative to the metal component of the structure might sometimes be polycarbonate strengthened with carbon fibre - or previously glass-fibre.
If you are unsure then check out the different types of structure you have been told about during the last few years at school. Simple cameras - like the promotional version on the left have no other strengthening feature additional to the case itself- they are often ‘shell’ structures.
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The barcode system reading into the camera details of the ISO rating (light sensitivity)
Still the same basic layout of lens, light-tight box and film plane but now in the electronic age many of the systems have become electronic. Viewing can be through a rangefinder system if in a manual focus design or simply a viewing lens. Motors control focus, sensors control the exposure needed by sampling the light at various points on the viewfinder image and the counter system and playback are activated as part of a sequence of events once the shutter button (the input) has been activated. It should be possible to create a simple ‘box-flowchart’ of what happens once the
photographer activates the shutter button. Have a go at doing the flow chart of ‘taking a picture’. As an intermediate point, cameras like this did still use film and sensors in the film cassette bay - where the film was placed - checked a bar-code on the side of the film can. This stored the information about the ISO rating of the film and so its sensitivity to light. Now a CCD or CMOS sensor - the elctronic sensor in digital cameras takes the place of the film. This works in much the same way as a simple scanner but instead of a single line of sensitive devices moves across the subject, an array of those sensors is positioned in a panel at the film plane position.
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