C100: C100 Dual Pixel AF in practice

J

Josh Bass

Veteran
Hi. Much has been written about this all over the web, but I'm still having trouble finding the specific info I'm looking for.

So I know how the DPAF in the C100 works (M1 and M2 seem to be identical, except for the sometimes available face tracking on the M2), it's the center box only. So, I guess what I'm trying to figure out is, if you're NOT centering/screwing up all your compositions for the sake of being able to use the AF, how well does it work? If you turn it on, get your focus point, then recompose, how well does it still work?

Let's take a person as the subject, for instance. Seems that at certain focal lengths/camera distances/f stops the difference in distance between a person's face and their torso would not be much, so if you focus on the face and recompose so the center box is now on the torso somewhere, the AF might still work on a follow/slider shot, depending on circumstance.

For less taxing shots (subject to cam distance doesn't change), I would think it would work even better, although it seems the one shot AF mode would work fine here too.

I'm not really thinking of AF for narrative work, rather for ENG/run n'gun stuff where you're working alone and trying to get people as the move around at an event or maybe some slider b-roll stuff.

Thoughts?
 
For non-center frame shots, yeah, you compose, turn on auto-focus for .5 seconds, turn it off, recompose. Focuses faster than manually focusing 9 times out of 10. Doesn't matter how fast of a focus puller you are; it focuses quicker than a human can.

For run n gun work, getting each of your 400 shots you film in a day in-focus 1-2 seconds faster is a big deal.

And then for center composed shots, you can leave it on while tracking your center framed subject, which is useful in a variety of scenarios (slider, Steadicam, a person approaching camera, etc.).
 
In my c300 Mark I, I can use the centre point AF to acquire focus and then use the 7 button to lock the focus, then recompose or pan and shoot. So If I am panning from say subject at point A on my left to another subject at point B on my right, then if I just pan with DPAF on, then the camera can lock focus on the background when I move off the subject A on my left. So just program the button 7, then use the DPAF to acquire focus and lock it by pressing the button 7. Then pan and when reach the pont B press the button 7 again to reaquire focus. switching on and off the AF button is not easy with all the still lenses.
 
Can you not assign the focus to a button on the C100?

Is the DPAF any FASTER than the one-shot AF for non-continuous use? I.e. is there any reason you'd use the DPAF for the focus/recompose with focus off scenarios instead of the one-shot?
 
I don't see the point to the one-shot. The advantage of the continuous is that you can have the auto-focus on for exactly how long you want it on for. I don't know, maybe the one-shot means you only need to press the button once; I haven't actually tried it hardly at all. But now if you suddenly have a center framed shot and you want to track to subject, then you'd need to go with continuous.

The grip button is mapped as the auto-focus button. It's typically the quickest button to access as your thumb rests on it while gripping the handle.
 
Point of the one shot would be to quickly focus on a subject where neither they nor you were moving out of the focus plane. E.g., at some event shoot where someone's standing around doing something you want to shoot, and you're standing somewhere in place for your shot, you one shot AF on them to grab focus quicker than you could manually and start rolling. Same way you'd use it for a still.
 
There are two modes that are accessed through menu, you know that. There are two buttons for controlling those two modes. You can use either to handle the above situation. It all depends on what you choose as your "default" for focus. I chose AF Cont. to shoot with last week and hit the AF Lock button to avoid hunting. Subject was rocking side to side but always in the DOF so no problems. Week before shot a tech film where the equipment never moved but the technician did. In that case, used One Shot mode controlled by the One-shot AF button.
 
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I don't own the cam so I'm actually not super familiar with the menu structure etc. I don't think the M1 has face tracking, read the M2 has it with the STM lenses. I'm looking at the M1 to purchase.
 
M1 definitely does not have face tracking, wish it did. I use one shot every time I shoot, rarely continuous. I do use it much like I would use it on a still camera, plant cross hair on target, hit focus, recompose and shoot. Works well, it's really hard to tell if you have sharp focus on the C100's screen or even on my Blade screen in bright sunlight, even with a hood. DPAF is crucial to my work, I would have a lot more OOF shots if I were using a non DPAF camera. I can do MF fine in a studio or indoors but a lot of my BTS is in nuclear bright daylight (two weeks shooting in the Sahara Desert in June) and DPAF saves the day for me. It is now exceedingly rare for me to capture an OOF shot whereas in the past with the 5D MKIII, a significiant percentage of my shots were OOF.
 
pure drifting and others - thank you for describing how valuable AF can be for you. I get tired in some other forums and FaceBook groups of constantly hearing some variation of "If you're a pro you never use AF." As an amateur, I don't care and don't get offended, but it is a bit tiresome at times. So it is refreshing to see some true pros say that it makes them, I suppose, "better" pros by the judicious use of a good AF system when it is appropriate.
 
wait Im confused...you say you use one shot a lot, rarely continuous, but then say dpaf is crucial to your work. isnt dpaf what they call the upgrade? or does that term apply to one shot as well?
 
ddixon said:
... "If you're a pro you never use AF...
Click to expand...

AF, even DPAF, is not infallible. I'm a beginner of sorts compared to most on this forum. I still expect to make money when I go out on a shoot. OOF results don't benefit anyone unless they are intentional. As mentioned by others here, AF can save considerable time and/or make the difference in capturing a quality image. AF, running wild, can ruin a shot as well. Using unqualified AF on a C100/upgrade or C100/2 is not a smart operating mode IMO. I would rather go full manual and stay on the focus motor 100% of the time. Remapping button 11 helped me...
 
Ah ok. Then I'll stop calling it DPAF and just say "continuous" or "one shot". As for pros never using AF, once my colleagues who are top guys in town with 35+ years in the biz start advocating it, that advice just becomes silly.
 
The uniqueness in Canon's application of DPAF on the C100/upgrade, C100/2 is concentrating on the center of the frame for normal AF mode. Other Canon products utilize close to the full frame for phase-offset detection. Offering Face Tracking is of little value and coupling that with entry-level lenses is, well, Canonesque. I don't use face tracking hardly at all. Because of this, I didn't know that FACE ONLY tracking AF works only in ONE SHOT mode, not CONTINNOUS. One other thing about face detection is that it only works when the attached EF lens is in AF mode. There is some rubbish on the web that suggests the C100 works like a C300 in this respect, don't believe it.

All it takes is some spoiled clips for one to decide how much weight to put on AF. I was there just recently because I wasn't paying attention to the camera modes.
 
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