#singlelensreflex

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The principles of a Single Lens Reflex (SLR) Camera are universal for analogue and digital photography. A basic definition of the word ‘photography’ is ‘drawing with light’ and a camera provides the means to capture light in order to create an image.

A cross sectional view of a SLR Camera reveals the inner workings of the mechanism. Light passes through the glass of the lens and then the aperture. The shutter acts as a barrier to prevent light exposing the Charged-Coupled Device (CCD) behind it and the light is reflected up into the pentaprism and eyepiece. This allows the photographer to view the exact composition that will be captured and to release the shutter at the appropriate moment. The CCD is then exposed and a photograph is created. Therefore, there are three variables to consider when producing a balanced exposure - aperture size, shutter speed and ISO. The respective creative effects of varying each are depth of field, motion blur and digital noise.

As a class, we worked with a partner to explore these constituent elements. Rob and I photographed each other with a range of apertures. In the first photograph, an aperture of f/8.0 presents Rob in focus with some of the more distant background details blurred. This may be considered a deep depth of field. The second photograph was shot with an aperture of f/2.8 and the foreground and background surrounding the subject are decidedly blurred. This is an example of a shallow depth of field. Creatively, it draws the viewer’s attention towards a specific area of the frame and it is a potent compositional tool. In the final photograph, an aperture of f/4.5 was used. When the subject is closer to the background, aperture choice becomes less relevant.

f/8.0, 1/640, ISO 800

f/2.8, 1/800, ISO 800