Shallow Depths of Field are Perfect for Close-ups

Next up is ‘depth of field’ (DOF).

Adjusting the focus of a camera will alter the distance from the lens of the point at which the image appears sharpest. The amount of the image that is in focus in front of and behind that point — in other words, the depth of the area in focus — is known as the ‘depth of field’. If a large proportion of the image is in focus, we say that the DOF is deep, also known as ‘deep focus’. If only the point of focus is sharply defined, and the rest of the image is blurry, the DOF is said to be ‘shallow’, also known as ‘shallow focus’.

These diagrams indicate how the aperture affects the DOF. In the top image, the aperture is wide open, leading to a shallow DOF. In the bottom image, the aperture is closed, leading to a deep DOF. When objects are viewed through a lens, points of light are transmitted to the rear focal plane (the location of the film or image sensor) as circles. These are known as ‘circles of confusion’ and their diameter is affected by the focal distance and the aperture size. The maximum size these circles can reach while the subject still appears in sharp focus is known as the ‘maximum permissible circle of confusion’.

It’s important to understand these three principles of DOF:

1) The closer you are to your subject, the shallower the DOF will be. The further away you are, the deeper the DOF.
2) DOF can be adjusted without changing lens. Open the aperture to make the DOF shallower and close it to make the DOF deeper.
3) Wide lenses give a deeper DOF; telephoto lenses give a shallower one.

When taking photos of cars, the initial aim is to have the entire image sharply defined (this is known as ‘pan focus’). The key is to use a wide lens and to gradually close the aperture (increasing the f/ value). Of course, you’ll need to choose the right point of focus first. If you were using the ‘front-on, 7:3’ angle mentioned previously, you would probably aim to center the focus on the car’s headlights.

All this talk of apertures has reminded me of my younger days. Back then, large-format cameras such as 4x5s were generally used for catalogue photography. 4x5s are extremely difficult to focus at the best of times, and trying to achieve pan focus with them is a real challenge. The aperture f/ value is usually something like 16 or 22, but sometimes with those cameras it went as high as 64. I remember being driven to tears by them, thinking it would be ten years before I’d be able to take a decent photo!

Anyway, once you’ve managed to take photos where the whole image is sharply defined, it’s time to get a little more adventurous. This means using a telephoto lens and being brave enough to open up the aperture and get snapping! You should see your subject standing out more from its background, giving it what you might call ‘independence’.

A shallow DOF produces more intense results, so it’s best used to take close-ups of individual parts, such as tail lights or rear wings, rather than for photos of the whole car. A shallow DOF is also extremely effective when you want a car to stand out from its background — for example, if you’re taking photos on a foggy day or if there’s a large building behind the car.