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Comment by s1mon | Hacker News Reader

To be clear, this is auto-follow-focus for video, not autofocus for stills. The post title is the same as the site, but really you wouldn't bother with this for stills. Follow focus is useful or essential for video production. On large shoots, there is a person dedicated to twisting a large knob which usually has white tape on it so the operator can write on marks for various focus depths that the director wants to hit at different times in the scene. Sometimes these follow focus systems are semi-automated to allow for smooth controlled transitions from one pre-rehearsed focus point to another.

The particular lens this is being demoed on is a 50mm f0.95, which will have a very shallow depth of field. Any minor focus error will be very apparent.

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To note, autofocusing adapters for stills already exist for the Sony E-mount system, however because of the closed API of the AF system it is difficult to enter the optical characteristics necessary for in-camera video AF.

This is exciting and I hope it gets extended to be usable for stills as well.

Manual focus fast lenses take quite a bit of practice to hit a stride with and this would make some of those much more palatable for casual use.

What would lidar focusing give still photographers that current hybrid phase-detect + contrast-detect autofocus systems can't? Better low light performance?

Aren’t there, uhm, lenses that autofocus? I get that are more choices for third party manual focus lenses, and that they’re generally cheaper, but the amount of stuff they’re buying / having to haul around to make this solution work seems to be pretty intense.

I guess this is most interesting for people who already use a gimbal, which is a tool that stabilises your camera for video, because until now you couldn’t use manual focus lenses, or at least not change focus during the shot, because operating the lens manually will interfere with the gimbal’s operation.

Most lenses that autofocus are all about reaching that focus point as fast as possible in order to take a still photo. When you are focusing for video, you're often "pulling focus" (i.e. adjusting the depth where you're focusing) very slowly, and sometimes back and forth between two or more set distances [1]. No autofocus lens is going to know what the director or cinematographer had in mind for the shot. At best you can have AI which will follow a moving object, or look for eyes, but that doesn't solve the general case at all.

[1] https://en.wikipedia.org/wiki/Focus_puller

Right, I know that, I should maybe have been explicit but I was replying to a commenter who suggested this setup for stills.

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