Before film became possible through Edison and the Lumière Brothers' fantastical inventions, theater had reigned as the primary dramatic performance artform for thousands of years. Though sharing much of the same lineage, there are fundamental differences in the way that film and theater are conceived, planned, acted, and consumed.
Diagetic space in film vs stage space in theater
Theater has, by its nature, a single frame through which everything is viewed. The stage (and sometimes the theater itself) forms the space which contains the entire epistemic system of the play. There are a number of meta-theatrical productions (Nunsense comes to mind) as well as a number of plays which directly address the audience as part of the set (Gypsy does this in the first scene; the theater is both the theater of our reality and the theater represented in the epistemological system of the play), but even then, the audience is still perceiving a series of actions and reactions which occur within the confines of a limited physical space. Theatrical productions tend to get around this through creative use of scenery and backdrop changes – but the audience’s frame of reference is still the stage in front of them.
Film uses the notion of diegetic space – the space which is in front of the camera, or can be perceived – along with the notion of non-diegetic action and sound which occurs off-camera. This means that the mise-en-scène can dynamically change and with it our perception of the action and dialogue taking place.
Montage theory and discontinity
Few films rely on a single non-changing perspective which would mirror that of a theater stage ; some of this may have to do with the inherent limitations of resolution and detail reproduction on film, but I would hypothesize that it tended to happen before films evolved from fixed camera short subject moving pictures. Following this train of thought, I believe that film technique evolved because the possibilities of a series of changing frames being stitched together through perspective changes allowed film to step outside of the confines of a single stream of temporally equidistant images.
Beyond traditional Montage Theory, which stresses continuity, film also opens itself to the possibility of discontinuous editing. This can enable innovative storytelling techniques like the one used in Deconstructing Harry or some of the ever-prevalent dream sequences used in much of modern film.
It should be noted that some aspects of film montage theory are present in certain theatrical works. Overlapping conversations playing out on different parts of the stage create a holistic montage effect by forcing the viewer to effectively produce “cuts” by swiveling his/her attention between two or more situations. This is not as formalized as actual film cuts produced by editing, as the audience still remains in charge of what they are choosing to see.
Forced perspective and shifting vision through the lens of the camera
As mentioned earlier, film relies on the notion of diegetic space to present its epistemological reality; this allows the filmmaker to force us to view the world through his/her eyes. Unlike a theater patron, we are not able to view the entire artificial world of the set to focus on different areas all of the time. Shifting to closer shots or differing perspectives forces us to view at least a part of this artificial world in the way that its auteur prescribes. It is a much less holistic view of that world when considered in that way.
There are several notions in film which reveal some of its theatrical roots. One of the most notable of these is the concept of the 180 degree rule. Having an imaginary line which (at least in most conventional non-arthouse cinema) cannot be crossed references the notion of a theater stage plane; no one can cross behind a theater set to view behind characters, and as such, we cannot understand jumping behind characters in most standard film editing montages.
Lens optics, light, and CGI
Theater is seen with a single lens: that of the human eye. It has a single focal length, a particular depth-of-field, and can only view practical effects (effects which actually exist in front of it). In comparison, the world of film is rife with variable length lensing, varying depth-of-field, and composited effects which did not exist during the on-set performances – not to mention post-production effects and color grading/correction.
Theater lighting is dynamic, insofar as it can be controlled via switches or an electronic console. But, during the observed performance, the lighting which exists within the confines of the visible set is the permanent light through which the performance will be viewed. If a light should be warmer or colder, it cannot be adjusted later, as that single performance (or set of single performances) are the only time(s) where that lighting will matter.
Impermanence over many performances vs permanence over a highlight reel
Theater is the act of propagating a story; effectively giving it a kind of permanence through the act of repetitive impermanence. A show taking place on a stage has a series of characters, props, and other technical considerations which come together specifically for that series of performances, then are dismantled afterward. Performances exist only in the moment when they are observed, to be carried on by memory or repetition by others. “Set strike” is an activity which signals the end of the life of a theatrical series of performances; the set is effectively buried collectively by the cast and crew members, perhaps to rise again through repeat performances in the same or different venue.
Film, in contrast, provides permanence through celluloid (and more recently digital medium). It is not a record of what has occurred. It is not a single performance. It is effectively a “highlight reel” of the most pertinent moments of a series of performances which has been stitched together by the skill of an editor and post-production crew. It can be viewed many times, but the only thing that will change will be the viewer; what has been captured on film is immutable and permanent.
Actors and the best take: splicing together performances
Taking that into consideration, it is important to consider the effect which using multiple takes and angles has on actors and the characters they portray. The editing process in film makes it possible to create that “highlight reel” of performances, as well as show the characters based on different aspects, angles, vantage points, and even different physical space. (Cheating angles is an example of this.)
Instead of forcing an actor to do all of their preparatory work beforehand, certain decisions can be made by the director and editor to allow multiple performance possibilities to be whittled down into a single succinct final product.
Stage actors cannot, for example, be cut off during a live theater performance if they choose to change an aspect of their character in that performance. On film, a director can call “cut” and have the actor adjust their performance to better suit the overall aesthetic of the film.
Subtle film and bombastic theater: effective emoting and communicating with the audience
The method actor may have trouble dealing with the confines of film. Instead of having a more-or-less complete world to work within, an actor may be faced with partial sets, chromakeying (greenscreening), and playing across from characters who are not actually there for their filmed takes.
Emoting is much easier for a theater actor when they are able to communicate with their audience, but this simply isn’t possible in a direct way through the medium of film.
Reactive theater and predictive film: communicating and responding to the audience
Both film and theater have an audience component to them. For film, it is a viewer which must interpret a number of factors to attempt to assess an interpretation of the auteur’s vision and the actor’s performances over one or more viewings of the same source material. For theater, the viewer can interpret a differing performance over multiple viewings – but they can never go back to a past performance or attempt to reinterpret something they have seen through the fresh-eyed perception of a different time in their life. For theater-goers, the performance changes every time it is presented.
Both audiences react to what is presented to them. In theater, performers often feed off of the reactions of theater patrons, which can fuel their performances or alter their reactions in response. Film requires a predictive approach, since the audience is separated by both time and layers of post-processing. Irving Thalberg famously ran stage shows of certain scenes of “A Night at the Opera” in order to measure how much time the Marx Brothers needed to leave for the audience’s laughter to die down between jokes – but most film productions do not have the benefit of such ostentatious overtures. Film actors have to predictively assess what their audience will be experiencing and tune their performances accordingly.
There are a plethora of differences between film and theater – and neither is clearly superior in terms of the benefits it offers actors or the people who watch their performances. I tend to favor film because of the level of permanence it offers, but I can see why others could (and do) favor theater.
I’d like to thank the group of film/theater actors who I had consulted about the acting aspects which differ between the mediums.