Focal length is a Cinematography term in filmmaking. In virtual production, the nuances of this term take on special meaning. Here, we break down the definition to give you a starting point.
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It is the measure of the magnification power of a lens, typically given in millimeters; the higher the number, the greater the magnification. Focal length is an essential factor when shooting scenes and is controlled both by hardware and software.
Hardware used to control focal length includes prime lenses, zoom lenses, and adapters. Prime lenses are fixed-focal lengths such as 35mm or 50mm which don’t change. Zoom lenses are adjustable between two different values such as 24–70mm and can be changed while filming. Adapters allow cameras to accept interchangeable lens mounts from different manufacturers, giving more freedom and creativity when using lenses.
Software can also affect focal length through cropping, changing aspect ratio, adding motion blur, stabilization, distortion correction and optical character recognition (OCR). Cropping can decrease a scene's field of view, resulting in closer shots without requiring any additional equipment. Changing aspect ratio can also make it appear as if the camera has zooming capabilities without physically having one. Motion blur and stabilization help smooth out shaky camera footage for smoother playback. Distortion correction helps correct distorted images to look more natural. OCR allows text written on objects within a frame to be identified and read aloud.
The importance of the focal length lies in its ability to create unique shots that would otherwise not be possible. Longer focal lengths help compress elements in the background or foreground, creating interesting visuals with strong focus points. Shorter focal lengths can capture wider perspectives with lots of detail or follow subjects in motion quickly and accurately. Having control over these factors give filmmakers much-needed flexibility when producing content.
Using the right techniques with focal length can be beneficial for shooting scenes. Utilizing different lenses, adjusting aspect ratios, applying post processing tools – all play into how well your final product looks. Some best practices include using prime lenses for low light situations due to their larger aperture size; use zooms for extreme wide angles; try to keep stabilization and motion blur settings moderate so you don’t lose details; and finally pay attention to what kind of image quality you want and choose accordingly when selecting lenses.