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Comment by phantomread | Hacker News Reader

Amateur photographer looking to learn more here. My initial impression is that a 35mm focal length on a full-frame/35mm film equivalent sensor would have a relatively _wide_ field of view (FOV). Or do I have that backwards?

My other thought is that the suggested lens can stop down to f1.8, which would give a nice narrow depth of field (DOF) and add a pleasant background blur, but it would also be harder to stay in focus during a call. If the person on camera moves forward or backward very much at all when the lens is at f1.8, they would be pretty blurry. So perhaps they could get away with a lens that just stops down to f2.8 or so, albeit with worse low-light performance (smaller aperture, less light coming through).

But take these comments with a grain of salt. It sounds like you have a setup that works well for you.

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Not the OP but the GP, FWIW:

On full frame I used 85mm 1.8 to get a a good FOV / DOF / proportions.

But it sat on a tripod 1.5 meters behind my computer and made the room a nightmare to navigate :D

35mm on FF would indeed be mildly wide (just on wide side of "normal" 50mm lens)

Yeah, not enough coffee - got my DOF and FOV mixed up.

In any case I find if you sit close to your camera, 35mm is a good FOV that will fit in your head and shoulders. The background blur for f/1.8 works well if you enable Servo Autofocus with Face Detect. It will momentarily get confused if you step out of the frame and back in again, but it can track a face pretty well after that.

Just checked using a camera and you're right; a person right around "conversation distance" from the camera focusing at 35mm looks pretty natural in frame for a video call. It sounds like I underestimated modern continuous autofocus. Great info from you and the sibling comments, thanks.

Most modern cameras have the ability to do constant autofocus in video mode, to varying degrees of quality and success. Usually they will try to follow anything that looks like a human face, or at least the brightest object in the field of view.

That said, even the greatest autofocus isn't going to be able to keep up with a person who moves around a lot at f/1.8 - so it's reasonable to stop down a bit if that's the case for your subject.

it's also dependent on the lens used.

> If the person on camera moves forward or backward very much at all when the lens is at f1.8, they would be pretty blurry.

The mirrorless EOS camera's (R series) have autofocus with face tracking which works quite well. At f1.8 you get 8cm depth of field at 1m distance so you'd have to stop down the aperture to about f4 if you want your whole head to appear sharp on video.

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