Motion Camera Work
Dolly Shot- A dolly shot is a camera technique that involves using motion control. The technique gets its name from the iconic dolly used to make the shot work. During a dolly shot, the camera is attached to a tripod or harness that is mounted on a rolling dolly - a large platform that in some cases is big enough to accomodate up to 3 operators! This platform rests on modular steel rails that can be extended or routed in a given direction. By sliding the platform and camera along the rails, the motion of the camera is confined to one axis. The rails also allow the camera and it's operators to negate the effect of uneven ground!
Pan Shot - the pan shot is similar to a dolly shot in that it adds motion along one axis to a scene. The difference, however, is that while a dolly shot has the camera change its physical location over time, the pan shot has the camera pivot in place. This type of shot is typically done with a long-handled tripod head called a "pan head". These heads often used liquid or oil-filled bearings to make the panning motion extra smooth.
Pull Focus - When a camera operator initiates a pull focus, they change the point of focus at a certain time during the scene. This is often used to change the audiences attention from one actor to another, or to create emphasis. A pull focus is done using a special geared knob that attaches to the focus ring of a lense. These attachements usually have a soft white rubber ring that can be marked with grease-pens or wet-erase markers to indicate specific focus positions.
Aperture - the aperture of a lense is a mechanical diaphram that opens and closes to control how much light gets into a camera. In motion film or video, we are usually stuck at a frame rate of 30 or 60 frames per second. Therefore, the only way we can control exposure is by changing how much light can enter the camera, or how well the camera can record the light (via film speed or sensor ISO). Changing the aperture has a knock-on affect: when we fully dialate the aperture we create a very shallow depth of field. In many cases this is desireable, but sometimes you want to have more than one subject in focus. Aperture is controlled via the f# setting on your camera.
(This range is suitable for landscape/wide/multi subject shots)
Depth of Field - depth of field is a term used to describe how much of a scene is in focus. It refers to the focus field in a given shot. This field is a matter of physics - the wider the aperture (opening inside of lense) the shallower the field due to how much unfocused light is let into the lens. When an aperture is set narrowly, only focused light is let into the lens, resulting into a larger depth of field. A shallow depth of field is frequently used in cinema - it creates that blurry background effect you see in most films.
Focal Length - focal length refers to the distance between the lense and the focal point, OR, the sensor of a camera. The focal length is usually recorded in milimeters, and has a direct relationship to the field of view created by the lense. A shorter focal length will give a much wider field of view than a longer focal length. Consider the wide angle and telephoto lense of photography. A wide angle lense is usually used for landscape shots, or to shoot in small spaces - it creates a wide field of fiew. Generally speaking, a wide angle lense has a focal distance of somewhere between 17-35mm. A telephoto lense has a very narrow field of view, and therefore a magnifying effect is created. Most telephoto lenses are rated between 150 to 400mm.