Lens Selection

Many would argue that lenses are at least as important as the camera when it comes to image quality because it is the lens' ability to focus light from the scene onto the camera sensor which governs what the sensor has to work with.

Poor lenses tend to result in pictures with chromatic aberration (reds and blues separate) and have poor contrast (no extremes of light and dark).

Note that poor contrast can be corrected digitally afterwards, but chromatic aberration is almost impossible to fix.

Every lens manufacturer employs techniques to get the best performance at different price points. For example, their more expensive lenses might use special low dispersion glass - which reduces chromatic aberation, but is expensive to produce. Sadly every manufacturer has completely different ways of identifying the quality of the lens; it is very difficult to compare lenses!!!

The Telephoto End is Best

The minimum focal length for Portrait or Boudoir photography is around 50mm (35mm equivalent) Most digital cameras have sensors which are smaller than 35mm and so we use a Focal Length Multiplier to calculate a lens' 35mm equivalent (there is an excellent article on dpreview.com). If you go much below this - into the wide-angle range - you start to foreshorten the picture. The effect looks quite amusing on pictures of dogs with huge noses, but it isn't a flattering look on models! As most digital cameras have zoom lenses it is very easy to frame your shots by zooming the lens - be careful you don't turn your glamourous muse into a Golden Retriever!

Maximum Aperture

Every lens has a maximum aperture, normally shown on the end of the lens barrel, written as a ratio e.g. 1:2.8 indicates a maximum aperture of f2.8 (which is very good!). Zoom lenses often have a range - in this example the lens has a maximum aperture of f2.8 at a focal length of 7.3mm, reducing to f4.1 at its telephoto end of 29.2mm. Incidentally, the Focal Length Multiplier for this particular camera is 4.8x so the zoom lens has a 35mm equivalent of 35-140mm.

The better the maximum aperture (remember that the larger the aperture, the smaller the number - so f2.8 is better than f5.6 etc) the more versatile the camera will be:

• The camera will be able to take photographs in lower light with faster shutter speeds - therefore less chance of blurring due to camera shake.
• The greater the aperture the shallower the depth of field, which is a great tool for producing stunning portraits.

Prime vs Zoom Lenses

Prime (non-zoom) lenses usually produce higher quality photographs than their zoom counterparts, and they will probably have larger maximum apertures at a significantly lower price. In fact it is often possible to buy two or three prime lenses for the same price as an equivalent zoom; as a rule they will perform a lot better than the zoom. The downside of course is weight and convenience.

The single most cost-effective step you can take to improve your portrait/boudoir photographs with a DSLR is to use a 50mm prime lens. They produced excellent results, allow you to shoot in lower light and don't cost the earth.