Talk to different shooters, and you're likely to get a variety of different views on the necessity of a follow-focus system. If you're a run-and-gun shooter, you may feel these devices are unnecessary. This goes double for ENG shooters who tend to keep it simple and pull focus with their hand on the barrel of the lens. Although you can operate a follow focus when flying solo, it's specifically designed with a camera assistant, or 1st AC, in mind.
"Pulling focus" is the art of focusing the camera lens. The 1st AC works with the camera operator, and they're in charge of setting the camera's aperture, zoom and focus. The mettle of the 1st AC is tested during mobile shots when both the camera and actors are moving in and out of a designated depth of field. The job of focus pulling is perhaps the most difficult and skilled job on the set. If a 1st AC is doing his or her job well, you really won't notice, but one small mistake can ruin an entire shot (or scene), and if the mistake is caught during dailies, it can cost a production a lot of wasted time and money.
In earlier times, if the 1st AC wanted a remote-control solution they were limited to the "whip," which is connected to the follow focus, allowing the 1st AC to stand at a distance from the camera. The whip was the only way for the 1st AC to pull focus in tight spaces and places where there just wasn't room for personnel beyond the camera operator. Today, 1st ACs have a variety of options to pull focus as some manufacturers have stepped up to the plate to enable both run-and-gun shooters and 1st ACs to pull focus—wirelessly.
One of the coolest things about iPhone photo apps is the ability to use the touch screen to focus. Simply touch on the part of the image you want focused, and you're done. The company Easyfocus has taken that very idea and redesigned it for professional applications. The Easyfocus system features five different means of pulling focus wirelessly.
In Manual Mode, the 1st AC can use the wireless controller to pull focus using a remote control that has a traditional follow-focus wheel. Tracking Mode allows you to follow your subject with the cursor on an LCD touch screen. Map Scan creates a topographic map of the set and makes that map available for export. Focus Mode automatically shifts the focus to the measured distance. Finally, in Ramping Mode the focus will switch from two focus points within a user-defined time frame. The connection to the camera is via Bluetooth. www.easyfocus.at