Lens Language

Now that I've entered my third year I'm going right down to the basics and focusing on building my skills from the ground up. As my previous blog would suggest I'm choosing to focus on filmmaking, and for the most part - seeing as it's where I feel I lack the most experience - focus on Cinematography. So for the next nine months I'm going to be pulling out all the stops; reading books and doing test shoot after test shoot.

I thought I'd do some basic research on lenses seeing as I still don't really know a lot about them. I consulted Cinematography: Theory and Practice by Blain Brown for some answers.

After placing the camera in relation to the subject it is time for the lens choice. The lens choice will affect a number of major parameters.

Field of view: this is the width that one is able to see. For example an 18mm lens has a view of about 76 degrees and and 600mm lens has a view of about 2 degress.

This is taken with a 28mm lens, hence the depth and wide view of the rocks.

Depth of field: this relates to how much of the image in focus. An 18mm lens will have more in focus than a 600 mm lens.

A 200mm zoom lens only allows the foreground to be in focus.

This photo I found is a great demonstrator of focal length alongside shallow and deep focus.

Focal length: a long focal length simply means that the image is zoomed in further, similar to looking through a telescope. The focal length also effects the depth of the image though. Objects appear to be less of a distance from each other and the image appears flatter.

So the greater field of view, the deeper the depth of field, the longer the focal length and the lesser the compression of distance.

Below is a table of lens types and fields of view.

18mm: 76 degrees

25mm: 51 degrees

32mm: 39 degrees

50mm: 25 degrees

85mm: 14 degrees

135mm: 9 degrees

300mm: 4 degrees

600mm: 2 degrees

Starting at around 0.44 this shot from Citizen Kane effectively uses deep focus to allow action and objects to be visible on multiple planes. In this way one is able to show a great deal of detail without having to resort to multiple shots. Here we see Kane's ill wife, her glass and medicine and the reaction of Kane himself all in one shot.

Here is a good example from the film Anuva Hood of a wide lens being used to show the subject within his entire environment. With such a wide lens you can see a fair bit of distortion, note the slightly curvy left hand wall in particular. I for one like this distortion as it adds to any intended comical effect.