What it is…
A tenet in continuity film editing which states that the camera positions between two consecutive shots should be separated by at least 30 degrees with respect to the subject. In other words, combined with the 180 degree rule, the difference in camera angles between two shots should lie between 30 and 180 degrees. Any violation of this range is expected to confuse the audience.
Why it is special...
The 30 Degree Rule is highly anti-intuitive in that it posits that a cut resulting in a greater change in camera angle would be less confusing to the audience compared to a cut that produces a smaller camera-angle change. This is possibly because we have been so accustomed to the conventions of narrative cinema that a cut which does not introduce a significantly different shot comes across as unwarranted.
When it is deployed...
Once a radical idea, the infringement of the 30 Degree Rule in the form of an Axial Cut or a Jump Cut has been assimilated highly successfully into mainstream cinema. Owing to their naturally rhythmic quality, these types of cuts are frequently used in songs or music videos, where editing rules generally take a back seat. They are also, to a lesser extent, found in action sequences and dramatic confrontations, especially when they are shot with handheld cameras.
Where to find it.. .
French director Jean Luc Godard’s Breathless (1959), which popularised the jump cut like no other film, employs a series of cuts in which the camera barely moves across the shots. Although borne out of necessity, Godard used these jump cuts reflexively to keep illustrating that what we are watching is just a film.
How it is used…
Jump Cuts
An intentional violation of the rule is the Jump Cut, where a seemingly gratuitous cut is made between shots without any major spatial difference. Such a cut manifests itself as a sharp jerk in an otherwise continuous shot. Many times, a series of Jump Cuts are used in succession (a concise depiction of a bank robbery, for example) purely with the intention of imparting a specific rhythm and mood to a scene.
Axial Cut
The Axial Cut is another type of violation of the 30 Degree Rule. Here, although the distance of the camera from the subject changes noticeably, there is nearly zero change in the angle that the camera makes with respect to the subject. Like Jump Cut, this results in what looks like glitches during a zoom or a tracking shot. The Axial Cut, however, is a much more conventional device compared to the former.