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Occasional Contributor
Posts: 7
Registered: ‎01-07-2020

Re: 16-35 f2.8 focus issue on video

I think you’re mistaken. The T6i is capable of servo AF in movie mode and I have the choice to turn it on or off. I can watch the AF work. It’s just slow on this lens.
VIP
Posts: 8,870
Registered: ‎08-13-2015

Re: 16-35 f2.8 focus issue on video


@Project wrote:
I think you’re mistaken. The T6i is capable of servo AF in movie mode and I have the choice to turn it on or off. I can watch the AF work. It’s just slow on this lens.

I beg to differ.  KV was correct,  as always. Your camera does not really track subjects. 

 

"Movie Servo AF" is exclusive to cameras with Dual Pixel AF sensors.  That camera has a Hybrid CMOS AF III sensor.  Read the description very carefully.  No where does it mention "tracking", just faster focusing.   I have that same sensor in my M3, and it does not track in Movie Mode. 

 

EOS_T6i_Hybrid_CMOS_AF_III.JPG

 

EOS_T6i_19-Point_AF_System.JPG

 

You must tell it where to focus, and hopefully your subject is under one of the AF points.  Also, with a wide angle lens your subject may be a little to far away for the camera to pick up out of the background.  Subjects almost need to fill the frame.

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"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
Esteemed Contributor
Posts: 3,612
Registered: ‎02-17-2016

Re: 16-35 f2.8 focus issue on video

Actually, the T6S does not have dual pixel either, just a slightly improved method for object tracking.

 

The T6i only has contrast detection focusing in video mode. This is inherently slower than phase detect focus. It can track, but not very well.

Esteemed Contributor
Posts: 3,612
Registered: ‎02-17-2016

Re: 16-35 f2.8 focus issue on video

From Adorama from an article comparing the T6S to the T6i :

"TheCanon T6salso comes with some notable shooting features including Canon’s SERVOAF in live view, allowing for some of the fastest refocusing and tracking capabilities in aCanon Rebel camera. If you’re an aspiring wildlife photographer or want to capture all theaction at a sporting event, SERVO AF will help keep the action tack sharp. Lastly, althoughboth the Canon T6s and Canon T6i can shoot 30 frames-­per-­second 1080P full HD video, theT6s includes an in­camera HDR­movie mode."

 

https://www.adorama.com/alc/0015165/article/Canon-T6i-T6s-Comparison-An-Enthusiast-DSLR-That-Meets-t...

Honored Contributor
Posts: 5,164
Registered: ‎06-25-2014

Re: 16-35 f2.8 focus issue on video


@kvbarkley wrote:

From Adorama from an article comparing the T6S to the T6i :

"TheCanon T6salso comes with some notable shooting features including Canon’s SERVOAF in live view, allowing for some of the fastest refocusing and tracking capabilities in aCanon Rebel camera. If you’re an aspiring wildlife photographer or want to capture all theaction at a sporting event, SERVO AF will help keep the action tack sharp. Lastly, althoughboth the Canon T6s and Canon T6i can shoot 30 frames-­per-­second 1080P full HD video, theT6s includes an in­camera HDR­movie mode."

 

https://www.adorama.com/alc/0015165/article/Canon-T6i-T6s-Comparison-An-Enthusiast-DSLR-That-Meets-t...


Notwithstanding all that blather, the bottom line is what it's always been: If you need to shoot video well, get a video camera.

Bob
Philadelphia, Pennsylvania USA
VIP
Posts: 11,902
Registered: ‎12-07-2012

Re: 16-35 f2.8 focus issue on video

"If you need to shoot video well, get a video camera."

 

Seems reasonable doesn't it?  I guess not.

EOS 1DX and 1D Mk IV and several lenses!
VIP
Posts: 8,870
Registered: ‎08-13-2015

Re: 16-35 f2.8 focus issue on video


@Project wrote:
I think you’re mistaken. The T6i is capable of servo AF in movie mode and I have the choice to turn it on or off. I can watch the AF work. It’s just slow on this lens.

There is a crucial and subtle difference between the AF systems.  Apparently, the T6i performs continuous AF by using contrasting colors.  It is not capable of actual subject tracking and face tracking around the viewfinder, in either movie or stills modes. 

 

You seem to be expecting face/subject tracking. By focusing on the closest contrasting colors, the camera may seem like it is tracking your subject.  But, it is not really tracking the subjects.  Subject tracking usually puts a moving AF square on the subject, as the subject moves around the viewfinder.

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"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
Occasional Contributor
Posts: 7
Registered: ‎01-07-2020

Re: 16-35 f2.8 focus issue on video

I may be totally wrong and maybe it’s a gimmick from canon but there is a Servo AF function in video mode that I can turn on or off. If it’s turned on, I can touch the screen on the subject I want to track and it will put a little white box on the subject and follow it around the screen as long as it’s within the field of view.
VIP
Posts: 8,870
Registered: ‎08-13-2015

Re: 16-35 f2.8 focus issue on video


@Project wrote:
I may be totally wrong and maybe it’s a gimmick from canon but there is a Servo AF function in video mode that I can turn on or off. If it’s turned on, I can touch the screen on the subject I want to track and it will put a little white box on the subject and follow it around the screen as long as it’s within the field of view.

Yup.  My M3 does the same thing.  It probably works just like your T6i does in both Live View and Movie Mode.  The "tracking" leans a little toward the gimmick side, though.  As long as what you're tracking is the closest thing to the camera, it mostly works, albeit slowly.

 

Try this.  Switch to Live View, and keep the camera stil..  Use AI Servo focusing..  If you can still Touch AF, then do it, and keep the subject still.  Now half press the shutter, and the camera locks focus.  How could you tell it locked focus?  The box changed color.

 

When you touch AF, the white box appears on the subject, and stays on the subject as the subject moves around the screen.  Now try half pressing the shutter as the subject moves around the screen. The focus box stays on the subject.  What happens when the subject suddenly stops moving?  The camera locks focus, right?  How could you tell it locked focus?  The box changed color.

 

In both tests, the focus did not lock until the subject was still.  The camera is not maintaining focus as it tracks a subject.  The focus lags behind the tracking.  The subject must come to a near stop for the AF to get a lock.

 

Now, if you try that same test on a camera body equipped with a Dual Pixel AF sensor, the camera maintains near perfect focus while the subject is moving.  It does not have to wait for the subject to stop moving before it can get an accurate focus lock.  Half pressing the shutter maintains a focus lock at all times.  

 

THAT is the performance difference between CMOS AF III sensors and Dual Pixel AF sensors.

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"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
Occasional Contributor
Posts: 7
Registered: ‎01-07-2020

Re: 16-35 f2.8 focus issue on video

Awesome explanation. Thank you very much!!
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