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Commercial Photography Technique - Depth of Field_

Commercial Photography Technique – Depth of Field

Using depth of field creatively can give a shot loads of style as well as a professional edge.

Thanks to the autofocus function found in most modern digital cameras, achieving clarity in your images is an easy task.

However, by controlling exactly how much of your photograph is in focus, you can add style and impact to your work and achieve some credible results.

Put simply, depth of field is the area around the subject of your photograph that is in focus. Point the camera at anything and, unless you tell it otherwise, it will automatically focus for you – the depth of field is the area in front and behind the point of interest in sharp focus. It ranges from a few millimetres to several feet and is governed by two factors – focal length and lens aperture.

When you focus your camera lens on an object far away and measure the distance in millimetres from the centre of the lens to your camera’s sensor, the resulting figure is the focal length. Zoom lenses tend to range from 28mm to 102mm – though serious telephoto lenses can come in at much higher – and the greater the focal length, the shallower the depth of field. Focus in tightly on a subject using your camera’s zoom control and only a small amount of your image will be sharp, but leave your camera at a wide-angle setting and you will capture detail across a much broader depth of field. Landscape photographers, for example, as well as those creating commercial photography and architectural photography will often set their camera’s focal length to the lowest possible setting in order to achieve image clarity from the front to the back of the image.

However this can be altered by changing your camera’s aperture setting. Inside your digital camera is the mechanical equivalent of the pupil in your eye, which dilates and contracts to allow more or less light in. The size of the gap – the aperture – is measured in f-stops, or f-numbers, and the wider the aperture, the less the depth of field. Conversely, the lowest number, f/2, is the widest aperture, going down to f/16 and f/22 for smaller apertures. At a setting of f/2, only a minimal area around the point of interest in your photograph will be in focus, whereas at a setting of f/16, your image will appear sharp all the way through the frame. Mastering depth of field is a critical element within commercial photography.

Controlling Depth of Field

Whether you want front-to-back sharpness or diffused backgrounds, understanding DOF is crucial.The term depth of field (DOF) refers to the zone of a picture in front of and behind a focused point that appears to be sharp.

There’s some serious physics involved with DOF, but it’s worth remembering that DOF extends to 1/3 in front of the focus point and 2/3 behind it. In other words there’s twice as much ‘depth of field’ behind the focused subject than there is in front of it.

The most commonly used technique to control DOF is to select an appropriate aperture for a creative effect. A large aperture will result in a shallow DOF or zone of focus while a small aperture will produce an image with an increased DOF - an effect often used for architectural photography.

Similarly, changing from aa short focal length lens to one with a longer focal length decreases DOF – that is, a 200mm will have proportionately narrower DOF than a 100mm. Also, with any lens DOF diminishes as you move the camera closer to the subject – the reverse is also true, DOF increase as you move further away from your subject.

DOF Preview – The Pros and Cons

A depth of field preview button allows you to pre-visualise how a given aperture will affect the DOF of a shot. This is a great feature for assessing the ‘look’ of a background. A downside is that the viewfinder becomes darker at smaller apertures.

How to minimise depth of field

Select a large aperture – for example, f/2.8 or f/4

Use the maximum aperture available for your lens
Shoot with a fast lens
Shoot with a longer focal length lens
Add a tele-extender
Move closer to your subject

How to maximise depth of field

Select a small aperture

Use the minimum aperture available for your lens
Shoot with a shorter focal length lens
Move further away from your subject
Make use of the optimum focus point (hyperfocal distance)
Use a specialist tilt-and-shift lens

This article shows the quality and variety of techniques that customers benefit from as part of our commercial photography and architectural photography service. Call now to discuss your requirements and timescales on 079101 68536.