A straightforward scene; my coffee table with the Fuji X100S and the latest copy of the RPS Journal (with a few other bits and bobs). Not the most exciting or imaginative of photographic compositions but one that can adequately demonstrate the power of, what is arguably, the single most effective technique in photography that can make almost any subject matter worth a glance – Shallow Depth Of Field (commonly abbreviated to DOF).
It is achieved by using a wide aperture on the lens. This was taken at f1.4 with a 50mm lens on my Nikon D800E and focused on the edge of the lens cap of the X100S. If everything in the image had been in focus, it would not have had anywhere near the visual impact or aesthetic appeal that it has.
There are, however, two main prerequisites to achieving such a result. For a start, the larger the sensor of the camera, the easier it will be to achieve shallow DOF. Compact cameras are generally just incapable of this because of their miniscule sensors and the effect gets easier to achieve as sensor size increases up to the industry standard maximum of the full frame 35mm found in the top level DSLRs. The second is the maximum aperture of the lens but the effect is closely related to its focal length also. Shallow DOF is easily achievable with maximum apertures of f1.4 and f1.8 with focal lengths from wide-angle to standard 50 mm (in terms of full frame). DOF generally gets shallower as focal length increases but it then gets more difficult and much more expensive to produce lenses with maximum apertures of anything less than f2. The Nikkor 105mm Micro lens, for example, has a maximum aperture of f2.8 but has an incredibly shallow DOF when used in macro mode at this aperture. The Nikkor 85mm f1.4 is a favourite for portrait photographers as it is so easy to isolate a subject from the background but, at £1,600, it doesn’t come cheap.
It doesn’t stop there. “Bokeh” is a term which describes the character and quality of the out of focus areas of the image with respect to Shallow Depth Of Field. Yes, believe it or not, the quality of blur is an important factor in determining overall image quality and the performance of a lens.
So, go ahead! Set your DSLR to Aperture Priority, your lens on f1.8 and savour the results.