On a film, professional cinematographers must be able to rack focus between two or more points as the talent or subject moves through a composition. They use a variety of tools like follow-focus units, focusing marks and cine-style lenses with oversized barrels and precision scales in order to make this happen. The highest-budgeted films even will include a dedicated focus puller to assist the camera worker to ensure that delicate focus isn’t lost during filming. Unlike still lenses, these cine-style lenses almost always sport a de-clicked aperture for performing subtle and silent adjustments to aperture and exposure during a take, as well.
Myth: Manual-Focus Lenses Are Outdated
Dedicated still lenses, on the other hand, are built for speed. The autofocusing system makes them very difficult to use with video features because the tiny servo units are noisy. These small autofocusing motors must move comparatively heavy lens elements at breakneck speeds to be able to track moving subjects and, while manufacturers certainly pay attention to mitigating noise in a still camera, faster autofocus always will trump silent operation for a still camera. While newer autofocusing systems like Canon’s Dual Pixel AF are attempting to address this problem, for most cameras, this results in the whirring autofocus noises that photographers have come to know so well. This is why many filmmakers using still cameras will work with dual-track audio, where audio is captured separately through a microphone to an expensive external audio recorder. This also adds an extra step in editing to be able to anchor the audio track to the video.
But there’s another solution! Manual-focus lenses are still being produced by a number of glass manufacturers like Schneider, Voigtländer, Nikon, Zeiss, Bower, Leica, Canon, Vivitar, Tamron, Sony, Olympus and even Lensbaby. Available for a variety of camera-mounting systems, there are several advantages to working with these manual lenses for both video and stills. If looking for a manual cine-style lens, those are available, too. Rokinon/Samyang produces a number of manual-focus cine-style primes at very affordable price points, which is a huge advantage to working with manual-focus lenses over autofocus models. As they lack expensive and heavy autofocusing systems and motors, they’re often available for hundreds of dollars less in comparison to the same focal lengths with autofocus lenses. This also makes manual solutions very lightweight and fast, as the optics can dispense with autofocusing considerations in favor of light transmission and lens efficiency.
While you must know depth of field by aperture and sensor size to focus manually with any success, there’s something to be said for working manually across the board. During video capture, it forces you to hone your skills and to think ahead in order to execute fine focus changes and focus racks while filming. Knowing how to plan for the sweet spot of focus will give you a tremendous leg up in the world of video, where focusing must be done continually. Similarly, working manually with stills will give you a finely tuned sense of predictive focus and "trap" focusing, where a focal point is established prior to the subject entering the frame. Manual lenses are also very useful for low-light shooting, where contrast and phase-detect autofocus can struggle to determine points of autofocus. Adding to that, unlike TTL autofocusing systems, manual lenses will work with almost any camera. That means that, thanks to an absolute litany of inexpensive lenses available on the secondhand market, your choice over lens can be as much about the organic, visceral quality of the image it produces as making an economic choice simply based on aperture and focal length.