But first: I want to thank everyone who has participated in the last rounds of discussion about the dialectic tension between craftsmanship and vision. Of course it’s not a new discussion. It has been an ongoing discourse as long as mankind has expressed him- or herself through the arts, and it’s a debate that surely will never end. Still, I find it kind of amazing that the two camps often seem to stick to their grounds, and never the twain shall meet. I am surprised about the fact that some think that technical knowledge is about rules, for instance, when it really is about possibilities. I am even more amazed when some think technique comes down to camera brands, or what lenses you use. Whatever camera you are using has absolutely nothing to do with it. Technique is about how you use whatever camera you have to express whatever your vision is.
This post will actually be about technique – so forgive me those of you who aren’t interested in photography or at least the craft of photography. I am not going to talk about how to get a perfect exposure or any technique for technique’s sake, though. Because that is something modern cameras are more than capable enough to take care of themselves, at least 90 per cent of the time. No, I want to talk about how you can affect your visual expression by technical tweaking. Some time ago I wrote the post The Essential Property of Photography. It was about the most distinctive element of the photographic language that relates to the shutter of the camera. Today I want to focus on the aperture. The element of the photographic language related to the aperture is a less specific property of photography than that of the shutter. The visual result of using the aperture creatively, photography has to share with videos and films. Even the eye function the same way, although we hardly recognize it ourselves because of the eye’s enormous capability to adjust. Nevertheless when aperture was launched with the first cameras it introduced a visual element that hadn’t really been seen in the arts before: That of limited depth of field. And that’s what I want to talk a little bit about today.
We all know that a combination of shutter speed and aperture together ensure a correct exposure whether it’s on a digital sensor or on film. And as I said, this is something the camera is good at. Basically. But the aperture has a much more profound role to play in terms of visual language. It determents the depth of field of any photograph. It can make everything from close-up to infinity seem sharp or it can make the focus only a couple of inches wide and knock everything else out of focus. How can we use that creatively? Fundamentally in two ways. By reducing the depth of field we can make the viewer focus on the main subject or we can create an illusion of three-dimensional depth in the photograph.
The fact that a picture in itself is two-dimensional gives rise to special challenges in order to transform the perception of three-dimensional depth onto the flat surface. Depth is simply missing in any picture. It’s not a new challenge and it’s something painters through time have dealt with in various ways. Among other means they have used perspective to bring out a feeling of depth. The ancient Egyptions rendered a man at the far end of a row of marching soldiers as large as the man closest to the observer, and thus really didn’t create much feeling of depth. The old Chinese did the same on their rice paper paintings, but they were still able to create a feeling of depth. They always placed near object down in the left corner and faraway objects in the upper right corner of the frame. So even if a mountain in the foreground and a mountain in the background were rendered at the same size, the painting would still be perceived as being three-dimensional. Eventually painters, particularly in Europe, started to utilized convergence of parallel lines and diminution of object size to create a feeling of depth. And during the Renaissance they even went to extremes, by exaggerating the effects of convergence and diminution.
With the use of limited depth of field it’s possible to create another sensation of depth. The eye can only focus on one plane at a time. Objects in front of or behind this plane appear more blurred the farther away they are from it. As a result, contrasts between sharpness and blur, creates an impression of depth. This is something we can use creatively in our photographic language. A shallow depth of field will at the same time make the eye stay on whatever is focused and this it’s a great way to clean up an otherwise messy or chaotic background.
Most people know that the use of a wide angel lens results in more depth of field than the use of a telephoto lens. But it’s not quite true. What really matters is the scale of the object rendered. If you move in with a wide angel lens so that the object is rendered at the same scale on the image sensor as with a longer lens, the depth of field will be the same with the same aperture, albeit the perspective will be completely different. With this in mind it should also make sense that a camera with a small sensor, give rise to more depth field compared to one with a larger picture frame. As a matter of fact most point-and-shoot cameras have so small sensors that it’s virtually impossible to effectively limit the depth of field. That is why so many photographers chose a so-called full-framed camera, simply to have more options to play with (among other qualities). So to summarize: The only two factors that affect the depth of field are scale and size of the aperture. Use it wisely in your visual expression!