[Forgeties79]

Because typically we use (usually wireless) whips to control lens elements. The 1st AC ideally is on a dedicated monitor with the setup in hand to pull as needed while the cam op handles the physical camera and focuses on framing and any movement.

[dist-epoch]

You also have the sonar/radar thing on the camera which can measure distance. Can that be hooked into focus so it's automatic?

[Forgeties79]

If you’re going to go through all that trouble you may as well just use a lens or cam body with a quality, built in AF. Way cheaper and the tech has matured greatly. Plus even with lower to midgrade cameras it’s easy to find a capable system with a solid codec you can color match enough with the rest of the movie. Even my GH6 I travel with can shoot 5.7k pro res

[dist-epoch]

I was talking about movie-grade setups, I was wondering why they need the sonar thing if they focus manually anyway. Maybe it's useful for post-production, as a depth field or something.

[Forgeties79]

Oh sorry I misunderstood your point. That is so the AC can get an accurate measurement from the sensor/gate to the focus point, which they then mark on their follow focus. Often it’s a few marks because a shot will have different items of interest or the camera is moving. When you’re shooting on film this is particularly important, but a lot of people also use it for digital sensors so you’re not eyeballing it or depending on focus peaking (though plenty of quality focus pullers can absolutely eyeball it most of the time). Boils down to the shoot you’re on and the process they want, or the importance of the shot, such as something with huge explosions and a flipping car where are you want to reduce any possible margin for error.