February 15, 2017 at 3:08PM

23

Autofocus or manual focus when filming from a driving car?

Hi,

I plan on filming a car scene in which one car is the camera car and the other is the subject car. Both cars will be moving; probably driving down the street and on the highway.

My question is which is better for keeping the subject car in focus: autofocus or manual focus? Or rather, which will produce better results in terms of footage produced?

Example of desired result: https://www.youtube.com/watch?v=On3Z-pr-MI8

I've been using manual focus up until now that I have to film from a moving car and I can't exactly control the environment this time. I will plan where to shoot, and how the cars will drive by each other but that might be about it.

Equipment used is a DJI Ronin and Sony a7s series (most likely a7sii) cameras with Atomos Ninja Flame. I'm not sure which lens yet as I will base it on whether I use autofocus or manual focus. I won't be able to control the zoom either and refocusing will be difficult as I have both hands holding the Ronin.

Any help would be much appreciated. Thank you!

3 Comments

From looking at the desired shots, I would say that you are best off with a wide lens (about 15-20mm) and a very high aperture (about f8). With that you wouldn't really need to pull focus.

If you want to do more close up and shallow depth of field shots, I would go for the 5D IV and an L Lens (obviously only if you still can change the camera). I have heard of mixed results from the a7S Line when it comes to autofocus on objects. The face tracking seems to be great, but not so good for stuff like cars. The 5D IV would be the safe bet.

February 20, 2017 at 2:45AM

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Similar to what Johan said, you'd be totally safe setting focus for an approximate distance and keeping it there (unless you're doing some kind of shoot needing a focus pull). At the kind of distance you might be shooting (similar to the example you linked), you'd be safe as low as f/5 probably. I'd probably roll as low as 3.5 if I was feeling it.

For reference to my own experience, the car shots in this spot I worked on (https://vimeo.com/173155412) were as low as 2.8 (shot of the car speeding up at 0:29, low angle), probably just above that for most of them.

February 22, 2017 at 6:45PM

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Chad Stembridge
Cinematographer
169

Oops didn't think anybody answered my question lol. Thank you for the tips! Appreciate it.

March 6, 2017 at 6:07PM, Edited March 6, 6:07PM

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Cee Kay
Aspiring Cinematographer
101

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