Brent Ramsey
Brent Ramsey

Brent Ramsey has spent over thirty years in the cinematography field where he has worked on television programs, films and commercials. He is currently a Canon Technical Advisor for our motion picture equipment.

Canon Cinema EOS C300 Service Upgrade Adds Dual Pixel CMOS AF Technology

February 24, 2014

A new optional feature upgrade, which activates Dual Pixel CMOS AF, will soon be available for the Cinema EOS C300. Beginning in May 2014, EOS C300 owners will have the option to upgrade to this new AF technology, which significantly improves the EOS C300’s focus search and acquisition performance. Dual Pixel CMOS AF was originally introduced in the EOS 70D DSLR in September 2013, and most recently offered as a feature upgrade for the EOS C100.

Although Canon’s Dual Pixel CMOS AF technology was not fully developed when the EOS C300 started shipping, it was identified as an opportunity to offer users enhanced functionality and added value at a later date. Canon has since developed the supporting technology to provide the benefits of Dual Pixel CMOS AF in a large sensor camcorder.

With the ability to make a subject stand out with a limited depth-of-field, comes a requirement to keep control over focus – especially when the main subject moves or the point of focus changes. Dual Pixel CMOS AF was developed so that control of focus during moviemaking is made easier and smoother. Dual Pixel CMOS AF especially expands shooting possibilities for lone users by providing smooth, accurate autofocus with a huge range of lenses.

Dual Pixel CMOS AF delivers more natural autofocus action for video, with less searching, by utilizing a combination of phase detection and contrast-based autofocus technologies. An added benefit of the new optional feature upgrade, when paired with Canon’s latest STM equipped EF lenses, is virtually silent lens drive, eliminating any audio interference while recording with a microphone attached to the camera body.

A modified EOS C300’s camera setup menu will have an “AF Mode” selection, offering the options of “One Shot” or “Continuous” autofocus modes. A new assignable button option will be added with this upgrade called “Focus Lock.” Programming Focus Lock to an external button will allow the operator to interrupt continuous auto focus, acquire a quick focus mark in the center of the frame and lock it in. By pushing the assigned Focus Lock button again, the focus mark will be released and a new Focus Lock point can be acquired with a smooth focus adjustment. Acquiring focus marks in this fashion should greatly enhance the quality of “live” focus transitions – excellent for nature and wildlife cinematography, news, sports or for venues like concerts, events and documentary work where an accurate – yet natural – focus transition is desired.

Additionally, One-Shot AF, added in the firmware release, will see huge improvements with this upgrade. Focus can be achieved about twice as fast as without Dual Pixel CMOS AF. Quick focus checks made with One-Shot AF can be counted on to look natural – without excessive adjustments and lens blurring as it searches for the correct direction to roll focus.

Also, Dual Pixel CMOS AF will work with every Canon EF lens that is autofocus-capable. For a service fee, an EOS C300 can be modified to activate Dual Pixel CMOS AF. This service upgrade will not replace the camera's original sensor and there are currently no plans to ship new EOS C300’s with this feature built in. Adding this feature upgrade will require that cameras be shipped to an authorized service center to have the work performed.

How does Dual Pixel CMOS AF work?

The individual pixels on the CMOS sensor in the EOS C300 are capable of both capturing light and performing phase-difference autofocus. Each pixel has two separate photodiodes to receive light. Image plane-phase detection requires signals from two locations.

Each signal is detected during AF and is used as a phase-difference detection AF sensor. During imaging, they are combined and output as one pixel.

What are the advantages of adding Dual Pixel CMOS AF to the EOS C300?
  • Continuous AF will now be available in the EOS C300 with all EF lenses – except for manual lenses, of course. An added AF LOCK function will allow users to change the framing while holding the desired focus point. This works really well for clean focus shifts (close to far, far to close). Continuous AF will only be available in the center of the frame.
  • AF is tuned for shooting video. This new feature places a high priority on image quality and natural, smooth focus movement that results in stable AF movement – essential for avoiding undesired blurring.
  • Improved One-Shot AF (supported by Canon STM lenses). Achieving sharp focus with the One-Shot feature will be about twice as fast with this upgrade and the focus will be natural without overshooting the focus point.
How will the EOS C300’s continuous AF work?

The continuous AF portion of the shot will be located in the center of the frame and will represent 20% of the overall frame vertically and 25% horizontally.

The new AF LOCK function will allow the operator to set the focus point and lock it, making it possible to change the framing while maintaining the same focus position. When a new focus mark is desired, another press of the button will allow the focus to gently roll to a new mark acquired in the center of the frame.

AF is tuned for shooting video. This new feature places a high priority on image quality with natural, smooth focus movement and results in stable AF movement – essential for avoiding undesired blurring.

How does this change the functionality of the EOS C300?

The EOS C300’s camera setup menu had an “AF Mode” selection available with a recent firmware upgrade. This offered the options of “One-Shot” or “Continuous” autofocus.

A new AF LOCK function will now be a new option for the EOS C300’s assignable buttons. While filming, users will push the assigned AF LOCK button to stop the Continuous AF from changing, and then push the button again to re-enable the Continuous AF feature’s functionality. Visually, the AF Frame transitions from gray to white when this done.

How does the EOS C300 avoid blurring while focusing?

Because the current One-Shot AF mode uses only Contrast AF, the focus movements when using it can be jerky with overshoot anomalies. By using the signal of Contrast AF as a supplementary addition to the Dual Pixel CMOS AF available through this upgrade, users will avoid major blurring that may be caused by the Dual Pixel CMOS Auto Focus’ inability to detect the direction the focus must move to achieve proper focus.

Without the supplementary addition of Contrast AF to Dual Pixel CMOS AF, the focus could move in the wrong direction, only to hit the end of its range and then change direction to find the correct focus point. Contrast AF can detect the correct direction, eliminating a random search for focus.

How has One-Shot AF been improved in the EOS C300?

By changing the EOS C300’s One-Shot AF feature from using Contrast AF to using One-Shot AF by Dual Pixel CMOS AF, the EOS C300’s focusing will be twice as fast than it is currently. Focus will be more natural and without overshooting or blurring while the camera performs an autofocus adjustment.

As Contrast AF can now detect the correct focusing direction, thereby eliminating a random search, a modified (upgraded) EOS C300 will focus twice as fast as an unmodified camera and with a more natural look and no overshoot. Quick focus checks made with One-Shot AF look natural, as if someone was pulling focus, without excessive adjustments and lens blurring as it searches for the correct direction to roll focus. In other words, editors will no longer have to cut around focus acquisitions made using One-Shot AF.

Who will benefit from these upgrades?

Anyone that already owns or regularly uses Canon EF lenses will certainly be excited by this upgrade. Dual Pixel CMOS AF provides continuous autofocus with any EF lens (except manual focus lenses, of course) spanning EF and EF-S, fixed focal length, wide-angle and telephoto lenses. 104 different EF lenses support One-Shot AF operation. The system marks a significant advancement with greatly improved AF speeds.

With these service upgrade improvements, operators should see a vast improvement in the ease of obtaining fast and reliable focus marks, while confidently making smooth, natural focus transitions within the scene. The factory-installed upgrade for the EOS C300 camera is targeted at users who regularly shoot moving subjects or who want a smoother, more natural-looking autofocus feature. Specific markets include documentary filmmakers, electronic newsgathering, sports productions, weddings and similar special events, nature and wildlife, and many others.

How do you get it?

This will be a factory-installed upgrade for the EOS C300 Digital Cinema Camera. Cameras must be shipped to an authorized service center and an upgrade fee of $500 will be charged.

The CDLC contributors are compensated spokespersons and actual users of the Canon products that they promote.

© 2018 Canon U.S.A., Inc. All Rights Reserved. Reproduction in whole or in part without permission is prohibited.