GH3 auto focus on faces during interview.

Laurence wrote on 4/4/2014, 4:58 PM
Last night I did some interviews for a church project. Since it wasn't incredibly critical, I tried something I've wanted to try for a while. That is, I set my GH3 on continuous auto focus with the focus recognizing and focusing on faces. That way I could just relax and ask my questions during the interview instead of constantly stopping to check focus.

It worked really well, and I think I will do it this way from now on. Focus was razor sharp throughout the interviews. Leaning in or problem. I will have no problem doing it this way in the future.

This was with an Olympus 45mm lens set to f1.8, so the depth of field was very shallow.


set wrote on 4/4/2014, 6:31 PM
Does the subject's lighting is very bright compared to the background?

If it is very bright, I think the auto can do its' job well.
Sometimes what makes me worry for my situation is a brighter background that make the focus 'more interested' to the back, rather to front subject.

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winrockpost wrote on 4/4/2014, 6:55 PM
please excuse my ignorance on dslr and mirror less cams, but during an interview using manual focus if the subject leans forward or back you lose focus ?
GeeBax wrote on 4/4/2014, 7:05 PM
Yes you do, because as the OP says, the depth of field was shallow.

Laurence, was there any hunting of the focus action?

Laurence wrote on 4/4/2014, 7:12 PM
Yeah, when the subject leans or moves, with an f1.8 at 45mm, my depth of field is really shallow and with manual focus it would be soft when they move. Autofocus on my Z7 was useless on interviews because it would always grab the center of the frame. With continuous focus and facial recognition it will stay on the face no mater where it is and keep that in focus.

The theoretical problem is that since the GH3 focus is contrast and not phase based, when the image does go out of focus, it doesn't know which way, and has to hunt for the focus instead of going right to it. This isn't unique to the mirrorless cameras by the way. Canon and Nikon DSLRs may use phase focus when they shoot stills as you look through the lens, but in live mode that you use when shooting video, they also focus by detecting contrast.

When I bought Nikon D5100, one of the sales points was that it did continuous auto-focus and could also find faces. This was one of those features that existed only for the sake of advertising. The hunting was truly horrible. Last night on the GH3 it seemed to work really well. Looking over the footage when I got home, any focus hunting was subtle enough that it wasn't a problem

I understand some of the new Sony cams have a sort of hybrid phase/contrast detection autofocus that knows if something is getting closer or further away when it moves. My little RX100ii might even have it.

Anyway, I'll have no problem just using continuous auto-focus on the face on my next interview. I feel pretty confident after seeing last night's results.
farss wrote on 4/4/2014, 8:05 PM
[I]"I understand some of the new Sony cams have a sort of hybrid phase/contrast detection autofocus that knows if something is getting closer or further away when it moves. My little RX100ii might even have it"[/I]

For sure a number of the newer and small Sony cameras have tracking focus systems that do seem to work quite well.

You're also spot on about some autofocus systems doing horrid things when they lose it. My EX1 seems to rack right out and then in to find focus and typically it's onto the nearest object in the frame. I guess the only positive I can say is it looks the same as what a real focus puller would do, yeah right :(

Assisted manual focus on the EX1 can be very handy as can peaking OR NOT :(

Glad you've finally found a good solution, this kind of thing drives me nuts as a one man band trying to shoot talking heads. I had a reasonable paying gig doing this for a while and to be honest this and everything else meant I was quite relieved when the client and I parted company.

Laurence wrote on 4/4/2014, 8:28 PM
What will typically happen is that I'll be shooting a testimonial for a 12 step program or something like that and the person I'm interviewing will lean forward a bit and start to tell me something really personal and interesting. I will (as nicely as I can) say something like "hold on for a second" and go and adjust the camera. When I turn around again the moment is gone. What do you do? Ask them to hold their position leaning forward while you focus and then have them start again with the same intensity in the same position? These aren't actors. The continuous focus on faces last night made it so easy. I set up the framing and the shot and then we forgot about the camera and just talked. Footage looked sharp and in focus throughout. If there was a separate interviewer and camera person it wouldn't be such a big deal, but there isn't and it is.
videoITguy wrote on 4/4/2014, 11:54 PM
i don't do dslr or hybrid - but in a silly question of sorts - I wonder why you are using focal length of 45mm?? - that seems just to wide and unnatural for portraiture to me. If I were using say a 35mm slr lens on a Canon ASP-C sensor - I would use at least a 60mm and more likely an 85mm which is going to give me an effective focal length of almost 100mm.
On video camcorder shoots this is where I am doing an equivalent shoot for talking head in a well lighted scene (3 point soft umbrella) with camera set to autofocus with little to no creep.
Laurence wrote on 4/5/2014, 12:16 AM
With the micro-4/3 sensor, that is the equivalent of about a full frame 90mm. I am going for head and shoulders and the camera is about 10 feet back from the subject to do this. I end up sitting to the side of the camera instead of behind it with the viewscreen tilted sideways towards me. Any longer lens and I would be shouting my part of the conversation from a distance. Any wider and it wouldn't be as pretty.

Interview framing looks like this:

I also used that lens on the closups in this short ad:
Byron K wrote on 4/6/2014, 11:25 PM
Thanks for sharing Laurence.
Wow! The video quality of the subject interviewed are great! The DOF background is really nice!

The one thing I did notice was, some of the interviewees were different sizes in the frame. Was this on purpose? It didn't take anything away from the messages they were presenting though. (:
ushere wrote on 4/7/2014, 12:32 AM
interestingly enough i often resort to rack focus as a fx in vegas - my z5 (with proper lighting) holds manual focus and fidgety talent really well so the odd 'pull focus' livens the interview up a bit ;-)

fldave wrote on 4/8/2014, 8:11 AM
I understand the autofocus on the GH3 is one of the best out there, and the GH4 is even better.
rmack350 wrote on 4/8/2014, 1:45 PM
That looks very good. It helps to have a nice big space that's good looking and runs deep. Good locations are a big deal!

I've never seriously shot video with my GH1 (aside from random clips) but I've always been impressed by the way it can track faces for focus. It helps not to be shooting a crowd of people, of course.

You've probably discussed audio in other threads but could you recap your setup?

Laurence wrote on 4/8/2014, 10:47 PM
Good locations are incredibly important. There was a guy I worked with several years ago ago who would spend forty minutes or so looking for the ideal location before shooting an interview. I was like "there's a quiet wall over there, why not just shoot there?" Then that evening I saw the footage and I've been doing my best to imitate him ever since. The talking head is the main event, but the setting is every bit as important.

Everything is natural light augmented by two little Z96 LEDs. I don't like LEDs for complete lighting, but for augmenting natural light they rock.

The audio is very simple. A Rode short shotgun just below the camera frame pointing up going into a Beachtek before going into the camera. I monitor off the camera. You would think that would give you a lot of ambient room noise and it does. I squash this with the Waves NS1 one fader noise reduction plugin. I LOVE that plugin! I used to export the audio to Sound Forge and use the Sony NR, or iZotope RX. NS1 works so well that I rarely bother now. I also used to use a lav a lot because it was closer and thus picked up less room noise. The noise reduction images the room noise such a non issue that I just use the shotgun. Plus, I think the shotgun sounds more natural.

The beauty shop voiceover was done by I pick out the voice from their online demos then send them a script and pay and get a flac VO emailed to me. I do my own voice first until the client is happy with the exact wording, then replace it with the pro VO after that. They have a lower non-broadcast rate for stuff like my theater ads.
Duncan H wrote on 4/9/2014, 2:44 AM
Thanks Laurence, I always like looking at your footage, the way you set up interviews really appeals to me and I think I continue to learn alot from your material. I also appreciate your description above, very helpful. I'm about to pin back my ears and buy a GH4 in the next few months, largely on the basis of your work.

Much appreciated, thanks.

Laurence wrote on 4/9/2014, 6:47 AM
The stills from the GH3 are really good as well. You should be "walking six inches off the ground" happy with the GH4.
Laurence wrote on 4/14/2014, 8:16 PM
This was all shot using the continuous auto focus on faces setting on my GH3. I framed it and let the lens focus itself. If they moved, the focus followed by itself. So nice when you are also the one doing the interviews.