C300: C300 MKII Face Detection in CLog2

ChristianMoriarty

ChristianMoriarty

Well-known member
We ran a job yesterday using: Canon Log 2, Cinema Gamut, and Production - Viewing LUT on the monitor out.
Face Detection was somewhat erratic and inconsistent. We attributed it to Clog2 being low contrast.
Lens was a Canon L 24-70 version 1.
In a sit down interview it would lock on but then have a mind of it's own - after a couple minutes - Cya - not a good idea.
In a B Roll set up with 3 actors in a scene FD could not identify all the faces and randomly find the center face - this set up was well lit at f4+.
Possibly could be the lens not being a 24-70 version 2.
 
I've had the same experience in Canon Log 2 but in my case with a Sigma 50mm F1.4. Quickly switched to Focus Assist.

Also found Autofocus producing unsettling effect when interviewing people outside. The face stays in focus but the out of focus background is constantly shifting as the head moves slightly. Solution is to shut down the aperture a bit
 
If it's a standard sit-down interview(the subject is just sitting there), why are you using auto-focus?
 
ChristianMoriarty said:
We ran a job yesterday using: Canon Log 2, Cinema Gamut, and Production - Viewing LUT on the monitor out.
Face Detection was somewhat erratic and inconsistent. We attributed it to Clog2 being low contrast.
Lens was a Canon L 24-70 version 1.
In a sit down interview it would lock on but then have a mind of it's own - after a couple minutes - Cya - not a good idea.
In a B Roll set up with 3 actors in a scene FD could not identify all the faces and randomly find the center face - this set up was well lit at f4+.
Possibly could be the lens not being a 24-70 version 2.
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AF ability to find and follow faces varies a lot with different glass. And strangely it's not always the newer glass that is 'better'.
Type of faces has a lot to do with it. The camera (C300mk2) simply won't recognize certain faces.
People wearing glasses makes it tricky, f.ex.
I mostly use One Shot AF + Manual Focus Assist. At least for now until Canon makes a better user interface. Continous AF will be very popular one day, but not yet.
 
Run&Gun said:
If it's a standard sit-down interview(the subject is just sitting there), why are you using auto-focus?
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Face recognition works in AF on the C300MKII. In a sit down interview the subject does not just sit there. They tend to move around, especially leaning forward and back. Like the above poster, I too user the Sigma 50mm 1.4 for interviews (incredible lens) so when wide at 1.4 which can look wonderful but also fraught with focus danger the AF/face recognition locks on to the face and follows the subjects movement no matter how subtle. No focus issues, at least I have not had any when shooting non log profiles.
 
Picture profile should not matter as the phase detect sensels are used to determine focus direction.
 
Run&Gun said:
If it's a standard sit-down interview(the subject is just sitting there), why are you using auto-focus?
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Good point Run&Gun but even when sitting down people move the top part of their body, lean forwards and backwards or nod emphatically. So if you are working with a shallow depth of field autofocus can be pretty useful. That's if it works well.

But I have to say you can take things too far, for instance if the nose is in focus and the ears are out of focus.
 
Jazzy Moire said:
Good point Run&Gun but even when sitting down people move the top part of their body, lean forwards and backwards or nod emphatically. So if you are working with a shallow depth of field autofocus can be pretty useful. That's if it works well.

But I have to say you can take things too far, for instance if the nose is in focus and the ears are out of focus.
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I guess I'm a little old fashion, but I would never use auto focus for a sit-down interview. Instead select an f-stop where that given movement will still be in focus. A smart phone app like pCAM is great for this type info on set.
 
The bulk of my work with s35 sensor cams is for network sit-downs and I'm usually using a CN-E 135 T2.2 or CN-E 85 T1.3 and sometimes a 70-200 f/2.8 for those. There are times we will have three cams on an interview: 1) reporter reversal, 2) medium-wide on the subject and 3) tight on the subject(collar bones up or tighter). I'm usually the tight shot and I can't think of any instances where AF would have "saved" me. I've had one or two interviews that did really keep me on my toes, but still do-able. Because really, once the interview starts, I have one responsibility and that's MY shot. I'm not worried about audio, I'm not worried about a second or third cam, I'm focused on my shot.

I'm with David, no auto-focus(not that I have a camera that does it anyway) on sit-downs. Too much to lose if it goes stupid in the middle of a great or emotional bite that can't be duplicated. Heck, I know of guys that used to turn their servos off on their zoom lenses during interviews so something crazy couldn't happen. You should be paying attention to your shot while you are shooting and be able to adjust and anticipate and adjust if the person is moving enough to cause focus issues. And if they are moving that erratically and constantly, say something to the subject. Most people will oblige.
 
Run&Gun said:
The bulk of my work with s35 sensor cams is for network sit-downs and I'm usually using a CN-E 135 T2.2 or CN-E 85 T1.3 and sometimes a 70-200 f/2.8 for those. There are times we will have three cams on an interview: 1) reporter reversal, 2) medium-wide on the subject and 3) tight on the subject(collar bones up or tighter). I'm usually the tight shot and I can't think of any instances where AF would have "saved" me. I've had one or two interviews that did really keep me on my toes, but still do-able. Because really, once the interview starts, I have one responsibility and that's MY shot. I'm not worried about audio, I'm not worried about a second or third cam, I'm focused on my shot.

I'm with David, no auto-focus(not that I have a camera that does it anyway) on sit-downs. Too much to lose if it goes stupid in the middle of a great or emotional bite that can't be duplicated. Heck, I know of guys that used to turn their servos off on their zoom lenses during interviews so something crazy couldn't happen. You should be paying attention to your shot while you are shooting and be able to adjust and anticipate and adjust if the person is moving enough to cause focus issues. And if they are moving that erratically and constantly, say something to the subject. Most people will oblige.[/QUOTE

Just to be clear we never shoot auto focus ever, especially in sit down - At a f2.8 I turned DPAF on to experience the technology.
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I've had this issue too. Turn on the LUT and that will make your auto-focus work as well when shooting with a non-log profile. That's been my experience.


For sit down interviews I don't use auto-focus. Well, I think I did once or twice. One time it caused an issue and the shot went slightly out of focus for a few seconds. The other time it worked pretty well. I just don't find it reliable enough though to use in a controlled situation where I can very precisely set the focus manually. I shoot tights around f/4 typically, so that gives me enough depth of field to handle slight movements of the subject. If I was say on an 85mm at f/1.2 with a subject that moves a lot, then I'd consider using auto-focus. I feel like auto-focus works better when the depth of field is shallower, but maybe that's just because manual focus (in general) doesn't work as well when the depth of field is very shallow.

I do use auto-focus for run-n-gun interviews sometimes, though I typically don't leave it on. I use it more as a one-shot AF, though I don't actually use the one-shot AF feature as I like how using the continuous AF as a one-shot allows me to choose exactly how long I want it on and off for. Most of how I use the AF in general is as a one-shot; makes getting the shot in-focus much quicker. You focus manually, it takes 1-2 seconds (sometimes longer, depending, such as if I'm on Steadicam, it can take 2-5 seconds due to ergonomics); auto-focus takes .25-.5 seconds.
 
I use AF all the time in interview type situations, when people are talking to camera or any other situation where the Face Detection will easily hold the face. Back when we did sit-downs with 2/3" chip cameras I used to be able to listen to what the subject said and change frame accordingly. With the transition to S35 or full frame sensor size and bad focus tools I stopped hearing anything the subject said. All my attention was transferred to riding the focus. (If it's one of those jobs where I pull my own focus...) With the focus tools of the C300mk2 I can finally start to listen to the subject (again) and adjust accordingly. Creative interaction with Director & Producer and others on the team is also significantly improved with the C300mk2 since I can turn off my focus tunnel vision.
 
Run&Gun said:
The bulk of my work with s35 sensor cams is for network sit-downs and I'm usually using a CN-E 135 T2.2 or CN-E 85 T1.3 and sometimes a 70-200 f/2.8 for those. There are times we will have three cams on an interview: 1) reporter reversal, 2) medium-wide on the subject and 3) tight on the subject(collar bones up or tighter). I'm usually the tight shot and I can't think of any instances where AF would have "saved" me. I've had one or two interviews that did really keep me on my toes, but still do-able. Because really, once the interview starts, I have one responsibility and that's MY shot. I'm not worried about audio, I'm not worried about a second or third cam, I'm focused on my shot.

I'm with David, no auto-focus(not that I have a camera that does it anyway) on sit-downs. Too much to lose if it goes stupid in the middle of a great or emotional bite that can't be duplicated. Heck, I know of guys that used to turn their servos off on their zoom lenses during interviews so something crazy couldn't happen. You should be paying attention to your shot while you are shooting and be able to adjust and anticipate and adjust if the person is moving enough to cause focus issues. And if they are moving that erratically and constantly, say something to the subject. Most people will oblige.
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All great advice.

I am fortunate enough to use a camera with face recognition technology that works. Auto focus is just another tool to help get the job done and is a technology that Canon have advanced considerably starting with the C100's continuous auto focus/focus lock. Auto focus still appears to be a dirty word to some when in reality it just keeps getting better and better. It works for me and I use it every day, there is no right or wrong way if the end result is a positive one. Happy Producer, happy client, that is my end goal. If there was a problem or if AF/face recognition sucked I would soon be told so by a highly critical collective of people I work for.
 
Plexi Head said:
All great advice.

I am fortunate enough to use a camera with face recognition technology that works. Auto focus is just another tool to help get the job done and is a technology that Canon have advanced considerably starting with the C100's continuous auto focus/focus lock. Auto focus still appears to be a dirty word to some when in reality it just keeps getting better and better. It works for me and I use it every day, there is no right or wrong way if the end result is a positive one. Happy Producer, happy client, that is my end goal. If there was a problem or if AF/face recognition sucked I would soon be told so by a highly critical collective of people I work for.
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Well said.
 
I would go so far as to say that I couldn't do a lot of my work without auto-focus. I used to shoot a lot of these projects with the 5D MKIII so coming from a FF sensor, trying to ride focus while running around the controlled chaos of a working TV or feature set, while staying out of the way of crew, out of talent's eyeline while still "getting the shot" is quite a challenge. Even with a hood and a good monitor, it is very difficult to see if something is in sharp focus when doing run and gun in intensely bright sunlight (I just got back from two weeks of shooting in 125F heat in the Sahara Desert, it was quite bright, requiring about ten stops of ND to hold ISO 850 and a 5.6 average aperture). When you are literally running and gunning, trying to track a director or star through layers of other crew, C-stands, jib arms, etc. the C100s DPAF in combination with the 18-135 STM IS and the 70-200 2.8 IS II when the light falls to dusk and night, is a Godsend. I have not yet shot with the C300 MKII but I am realy looking forward to using the face detection, it will be even better for a lot of my work. Back in the day, nailing focus with my Betacam in SD or even with the old Varicam in 720p used to be really easy but once we went to S35 imagers at 1080 and 4k, achieving consistently sharp focus on moving subjects where I am handheld and they are moving, I will take all of the assistance I can get. In the end, all that matters is me in the edit bay with the client and editor and seeing nicely exposed, razor sharp focused images. My clients don't care how I get it, they just care about the end result. I am constantly zooming to frame up shots and riding the AF button with my left hand, while riding iris and starting and stopping recording with the my right, DPAF makes life simpler for my work.

I will use the AF for sit down interviews just to get a good starting point but then I go to manual and track them as they move back and forth in Z axis space. I shoot a ton of green screen interviews and I typically use my 85mm 1.8 at F 2.2 to 2.8, I don't have powerful enough portable ighting kit to go for F4 or 5.6 unless I want to gain up, which I dislike doing for green screen composites. 2.2 to 2.8 on the 85mm at 8-10' tp subject with a S35 sensor gives me enough DOF where I don't need to tweak it too much unless they lean in and out a lot. Few of my subjects do that. I am looking forward to moving up to the C300 MKII within the next six months.
 
I find it insulting to infer that us camera ops' manual focus skills are so poor we need a machine, a robot, auto-focus, to do a better job than us. I was on a shoot a few weeks ago where we had a 24 foot Jimmy jib, with no wireless follow focus, shooting with a 5D at f/1.0 on a 50mm. So we put a 30 lb three year old child on the end of the jib and he rode the manual focus like a champ. Not everything was in-focus, but we were shooting 5D; that art is not supposed to be in focus all the time. Better to have some organic imperfections of the child's AC work than a sterile and perfectly in-focus shot that a machine could be capable of. The kid had a blast too, until he fell.
 
Parrot said:
I use AF all the time in interview type situations, when people are talking to camera or any other situation where the Face Detection will easily hold the face. Back when we did sit-downs with 2/3" chip cameras I used to be able to listen to what the subject said and change frame accordingly. With the transition to S35 or full frame sensor size and bad focus tools I stopped hearing anything the subject said. All my attention was transferred to riding the focus. (If it's one of those jobs where I pull my own focus...) With the focus tools of the C300mk2 I can finally start to listen to the subject (again) and adjust accordingly. Creative interaction with Director & Producer and others on the team is also significantly improved with the C300mk2 since I can turn off my focus tunnel vision.
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Yep. And imagine taking it one step further and trying to ride focus and conduct the interview at the same time. I do this for about 90% of interviews I shoot. I would venture to say there are next to no people on this board that can do that effectively. It's all about using the tools for the specific job and situation. If you need AF and it works better than the alternative. USE IT!

And suggesting someone sit still during an interview is a terrible idea. It makes the person too self-conscious, and stiff.
 
There are some super sharp guys in hollywood who can nail focus all the time- outliers. Rest all are mortals who often mess up their focus. If the focus plane doesn't pass through the desired place for eg eyes of the subject then it is mostly no good for me. I do kind of pixel peeping to see if I nailed critical focus. Despite people in this and many other forums talking about how good they are in manual focus, I see a lot of mis-focused shots. DPAF is very good and the next iteration will be even better. One has to understand the limitations of DPAF as of today and use it accordingly.

I wish the LCD of the C300 Mark II had the 1DX II like touch screen.
 
I have used mine from time to time in sit down interviews, however I like the Box method alot better than face detection. I have noticed that face tracking is not always on the mark.
 
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