[josephg]

This is only true for photography.

For some reason, cinema lenses are still - for the most part - purely mechanical. For film and TV, most camera operators still focus manually - often via gears attached externally to the lens.

Coming from modern photography, manual focusing is inconvenient and difficult to learn. But there's something very old-school cool about cine lenses. They feel great.

[toast0]

Autofocus is very nice for photos, especially when it works.

Autofocus in moving pictures isn't so great. It might be nice when you're not filming, but while filming, a focus change should really be intentional; auto focus isn't that. Might depend on what you're filming though.

[josephg]

> a focus change should really be intentional; auto focus isn't that. Might depend on what you're filming though.

As a solo operator, autofocus is great. Maybe the right metric is the number of crew per camera. 2-3 crew per camera? Manual focus is fine. 2-3 cameras per crew member, like solo filming a podcast or a theatre show? I'd choose autofocus every time.

[schobi]

Well.. The automatic part comes from the camera directing the settings mostly. The lens would be motorized focus/aperture.

For motion picture cinematography, I've seen remote controlled focus anyway. I don't see why you could not have a good motor built I to the lens and remote control it. If the external motor focus is quick and precise enough, then the internal motors should be as well.

[bzzzt]

If you're just filming a/your talking head autofocus with face recognition is very reliably and helps when people unintentionally go out of focus ;)

[pastel8739]

I think in cine it’s a lot more important to have smooth focus and to be able to control the focus speed, hence the MF lenses

[aeturnum]

I also think cine lenses have the budget to continue making high quality mechanical interfaces. Consumer lenses must have AF and so are incentivized to reuse that functionality if it would reduce the BoM.

[josephg]

Hm, I'm not sure about that. I suspect autofocus motors are much more expensive to manufacture than mechanical lens throws. They're almost certainly more expensive to design. I don't know about other manufacturers, but recent sony lenses contain 4 autofocus motors, and they can snap autofocus in tens-to-hundreds of milliseconds depending on the distance. Where do they even put those motors in the lens housing?

Its probably a scale thing. Photography lenses make up for the design, engineering and manufacturing costs with scale. Everyone who takes photos needs lenses. But far fewer films are made, and cine lenses are often rented. So they really can't be manufacturing that many units in total. I suspect they don't manufacture cine lenses in high enough volume to justify the engineering costs of fitting complex microcontrollers and motors into the lens housing. And if the production can afford to hire a focus puller anyway, autofocus just isn't that valuable.

[salvagedcircuit]

A large focus throw and more importantly, focus consistency, is paramount for cinema lenses. When you rack focus, the lens needs to show the same field of view every time, no questions asked. The early red pro cinema lenses had a design flaw where the focus rings would come loose over time and ruin shots. Someone clearly forgot the threadlocker.

[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.

[PowerElectronix]

I think people in cinema have (and want) more control over the take. For a photographer, autofocus is quality of life, for a cinematographer it can get in the way very fast in everything that's not following subjects.

[superjan]

When telling a story through film, changing what depth is in focus is a great way to move the viewer’s attention, without the need for cutting to a different angle or camera movement.

[josephg]

Sure. But most shots have a deep depth of field or just follow one person. Even when autofocus isn’t needed, you can just turn it off. It’s just kinda weird that they don’t include the feature at all.

[salvagedcircuit]

Indeed! I've had the privilege and honor of collimating a Cooke s4i. It's a thing of beauty, joy forever.