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Digital SLR Photography

SLRs are characterised by use of exchangeable lenses (although a very few do employ a fixed lens or attempt to emulate SLR design using an LCD viewfinder in place of the roof mirror or pentaprism). It was an inevitability for the likes of Canon and Nikon to ease the passage of professional photographers from film to digital by introducing dSLRs to their model range. Quite apart from facilitating the look and feel transition, such cameras were designed to make use of stock existing lenses already owned by users. Professional lenses are not cheap, most if not all costing more than the processing body – the camera – they’re delivering light to. It made sense, and Canon produced a number of top quality cameras designed for professional use. And within a couple of years they were soon to produce one of the best selling dSLRs of all time, the prosumer EOS 300D.

“The EOS 300D kick-started the digital SLR revolution, becoming the best selling model of all time… the EOS 350D Digital will now take over, playing a major role in Canon’s digital SLR strategy,” said Mogens Jensen, Head of Canon Consumer Imaging Europe. “Canon predicts the dSLR market will double in size by the end of 2006.”

Other manufacturers were not to be left behind, with Nikon producing the D70 dSLR and other brands entering the field with comparably equipped, similarly priced models.


The advent of dSLR cameras sparked growth in lens development to accommodate the differences in film and digital cameras, notably that of focal length and film/sensor size, with digital cameras generally having smaller sensors and longer focal paths. This meant that the lens characteristics designed for film would change when mounted on digital camera bodies. In worst cases lenses would mount but then not clear the mirror shutter mechanisms, and most delivered images with restricted fields of view and higher magnification factors.

Soon, however, lenses designed specifically for digital cameras – apart from those already existing from the originating camera manufacturers – hit the markets. Their characteristics better matched the build features of dSLRs and also exploited the differing light gathering and processing properties of digital camera circuitry. More importantly from the prosumer’s perspective they were comparatively cheap.

Manufacturers like Sigma and Tamron produce low cost lenses for a number of digital cameras from manufacturers like Canon, Nikon, Konica Minolta and Pentax. They are of decent built quality and represent good value for the amateur or semi-professional photographer or, indeed, for budget conscious users wishing to experiment with digital photography.

Lens Types

There are three types of camera lens, whether in film or digital photography: standard, wide angle and telephoto. The magnifying power of lenses is measured in millimetres, 50mm being an accepted standard for a normal focal length.

Lenses of shorter focal length – 24mm to 28mm – are considered wide angle and are generally used for landscape photography, while longer focal length lenses are used in telescopic work for nature or to bring the action closer and can have focal lengths of 500mm to 1000mm and greater. Macro lenses are another type, though less common, and are designed for close-up work on objects where detail must be revealed such as when photographing flowers or insects or to illustrate technical artefacts like motherboards. Other types of optics or ‘glass’ exist for specialist work or to correct limitations inherent in capture of certain type of objects.

Choosing a lens can be a time consuming process but it is usually safe to spent a little extra on a decent standard 50mm lens supported by a mid-range telephoto and a wide angle lens for landscape and group shots. As ever, price is the dominating consideration. A decent prime or fixed focal length lens can be expensive but pays for itself immediately in terms of image resolution detail and sharpness. When buying a good telephoto lens be prepared to pay around $1,500. Professional quality telephoto zoom lenses will easily cost in excess of $7,500.

Lenses are either powered by electric motors, manually focus adjusted, or both. Further, many now sport USM (Ultra Sonic Motor) focusing, a quick and quiet mechanism first developed by Canon but tend to be more expensive.

Whether buying a dSLR or compact digital camera, many lenses now support image stabilisation technology to compensate for camera shake or offer the opportunity to get closer to the action using a zoom lens and not risk blurred images.

Choosing a Digital Setup

Buying the correct type of digital camera and lens configuration need not be too difficult provided one has a clear understanding of requirements. For normal 4 x 5.3 prints a 3 megapixel camera is adequate, whereas 8 x 10.6 requires double the resolution, 6 megapixels. There are numerous relatively inexpensive consumer compact models on the market that will produce excellent output for a few hundred dollars, suitable for general purpose work.

The more difficult decisions must be made when deciding whether to go for a digital single lens reflex or fixed lens model but here it’s a question of expectations. The more expensive fixed lens cameras, while offering a good feature set and perhaps a zoom lens, are inherently restricted in use and, since they are mass-produced, no matter how good the image sensor is, the lens quality must be factored into production costs and therefore will unlikely meet the imaging quality found in a decent dSLR lens.

Anybody taking up photography as a hobby or semi-professionally must really consider buying a prosumer dSLR and a range of good lenses to complement the camera body.

Selecting specific cameras and lenses takes a little time but there are magazines and websites offering reviews on present and past models which will aid in the decision making process but it’s up to the individual to research their needs and set their budget.

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