Canon EOS C100 Dual Pixel CMOS AF Problem with stm

[iisaicontest]

I just upgrade my C100 firmware "DUAL PIXEL CMOS AF UPGRADE" from canon service centre, and the focus speed really fast, but somtimes it take Several times to found the focus point.(re-focus)  with my stm lens. it work fine using firmware 1.0.3.1.00.

sample 1: https://www.youtube.com/watch?v=scQN0...
sample 2: https://www.youtube.com/watch?v=rv_iv...
sample 3: https://www.youtube.com/watch?v=Vmqlp...
sample 4 : http://youtu.be/dSdxix2cDWI

Before upgrade : c100 firmware ver. 1.0.3.1.00
After upgrade : C100 Firmware ver. 2.0.3.1.00
Lens Firmware ver. 1.5.0
test Lens : Canon EF-S 18-135 F/3.5-5.6 is stm
Focus Length 135mm
ISO 1600 Shutter 1/50 F5.6 AF_on IS_on

[jefbak]

Are you focusing in the AF focus area box (pretty small area I've noticed)?

I have the 24-105mm EF lens but I am thinking aobut getting the new 10-18mm EF-S STM lens so I am curious about dual pixel AF support and performance.

I really increased the funcitonality of the new AF by setting button 7 (usually the magnify button) to AF Lock and the that make it much easier to use autofocus AND reframe the picture (so the subject does not always have to be right in the center). That tip came from Phillip Bloom, who has a video on Canon about it: http://www.usa.canon.com/cusa/professional/standard_display/eos_c100_feature_upgrade