The Mark of Quality - Shallow Depth of Field

There are many things that add to the quality and production value of films. One of these things in particular is often confused or misunderstood, and that is the effect of using a shallow depth of field. Of course there are a lot of other things which can add a huge difference to the quality of your film, but by using depth of field effectively helps bring your film out of that amatuer/student look just that much more.

One of the most common words I used to hear around film shoots was depth of field. "Give me some good depth of field", or "I want to have really deep depth of field around this character". This is a common misinterpretation, as having a deeper depth of field just means that more things will be in focus. Its when you severely limit or have a shallow depth of field that you get the nice blurring of objects surrounding the object in focus.

The main reason a shallow depth of field works to your advantage are two-fold. First, it makes the image more visually interesting, as it is a technique used more on bigger more professional productions. Secondly, it eliminates any extraneous detail from the picture and makes it lot more similar to how the human eye focuses. Human eyes can only focus on one area of interest at a time, and even when scanning a whole room or area the eye jumps focus from spot to spot, instead of taking in the whole scene as a whole. By introducing a shallow depth of field to the shot, it tells the audience exactly what to look at and what is important, since they can't see anything else in great detail. They must automatically focus on what is on focus.

Of course, with most consumer or pro-sumer grade cameras it can be hard to achieve a shallow depth of field without using some tricks. The main reason for this is both the sensor and lens size, as having a larger sensor or film size automatically makes shallower depth of fields easier to achieve. 35mm and 70mm film often gives the best results, since the film sizes are absolutely huge compared to their digital counterparts. The 35mm film is roughly 1 1/3 inches, and 70mm 2 3/4 inches wide. By comparison, most digital sensors are either 1/8 or 1/4 inch which is a huge difference, with some of the more improved and new sensors being 1/2 inch.

Often the only way to bring out a shallow depth of field with these tiny digital sensors is by physically moving the camera far away from the subject you wish to film, then zooming in as far as possible. A tripod comes in handy for using this technique, because the more zoom you're using the shakier the image is going to be. Once you achieve good focus on your subject, you should find that there is a shallow depth of field. Another technique is by shooting in slightly darker conditions, and opening the iris as far open as it will go. Using both these techniques compresses the image onto the sensor, which helps to limit the depth of field.

As you can see with both techniques, it may not always be possible to achieve good results. Sometimes you simply can't move the camera back any further, or perhaps you have to shoot on a bright sunny day. The only remedy to this is to either plan your production to try and make it easier to get shallower depths of field, or simply use a camera with a larger sensor size.

Here are a few examples of shallow depth of field in my own work: