Canon 5D Mk IV dual raw pixel mode

The new Canon 5D MK IV has been announced and is available in Australia, the USA and elsewhere from September 8th, around 4 years since the 5D Mk III was released. Body only is US$3,500 or A$5,200.

The camera has

  • 30.4MP Full-Frame CMOS Sensor
  • DIGIC 6+ Image Processor
  • 3.2″ 1.62m-Dot Touchscreen LCD Monitor
  • DCI 4K Video at 30 fps; 8.8MP Still Grab (grabbing a still without upsetting the video recording)
  • FHD 60fps, and HD resolution 120 fps (720P)
  • 61-Point High Density Reticular AF
  • Native ISO 32000, Expanded to ISO 102400
  • Dual Pixel RAW; AF Area Select Button
  • Dual Pixel CMOS AF and Movie Servo AF
  • 7 fps Shooting; CF & SD Card Slots
  • Built-In GPS and Wi-Fi with NFC

The features that really grabbed us were the 4K 30fps, the Dual Pixel RAW modes and the built in GPS and Wi-Fi.  While many of the features are welcome, such as the camera can now take 7 RAW frames per second (up from 6), and has stronger low light capability, it is the dual mode and 4K Video that are particularly of interest.

Canon’s new Dual Pixel CMOS AF function is for phase-detection autofocus in live view or movie capture. The Dual Pixel Raw (DPR) allows you in post-production to do shift the apparent focus small amounts after a picture has been taken.

It does three things in post (and not at once)..

  • Minor focus adjustment (think: ‘from nose in focus to eyes’ for a portrait not ‘desk to window vista beyond’ level adjustment). It would be great for Macro work for example.
  • bokeh, or
  • ghosting reduction
Focus adjustment
Focus adjustment
bokeh adjustment
bokeh adjustment

See video below using Canon’s DPP software (beta).

The Canon 5D IV includes a touch-screen to help you get the most from this new feature. Where as the 1DX II had limited use of it’s touch-screen during movie capture, there are no such limitations on the 5D IV. Instead, you can use the touch-screen to specify your subject for autofocus either in movie mode or in live view shooting.

 

The new Raw mode is built on the Dual-Pixel CMOS AF technology seen in the 70D. This on-sensor phase-detection autofocus system has been a mainstay of its higher-end DSLRs since 2013. The split-pixel design means that every pixel on the image sensor has two halves, one looking left and the other looking right. This in turn means that every pixel can serve as a phase-detection pixel, potentially usable for autofocus.

DPR-canon-5d-mk-iv

Phase detection for autofocus is achieved by dividing the incoming light into pairs of images and comparing them. The system uses a beam splitter (implemented as a small semi-transparent area of the main reflex mirror, coupled with a small secondary mirror) to direct light to an AF sensor at the bottom of the camera. Two micro-lenses capture the light rays coming from the opposite sides of the lens and divert it to the AF sensor, creating a simple rangefinder with a base within the lens’s diameter. The two images are then analysed for similar light intensity patterns (peaks and valleys) and the separation error is calculated in order to find if the object is in front focus or back focus position. This gives the direction and an estimate of the required amount of focus ring movement.(See wikipedia for more).

 

diode


Canon has taken this technology and stored the additional data into the special RAW DPR files for use in adding more focus back in during RAW processing. Given how phase-detection in AF works, and that essentially every pixel on the 5D IV’s sensor has two halves, looking in opposite directions from each other, “it makes sense that the point of focus could be shifted slightly, with some fancy image processing” – Imaging Resource.

 

cmos

Downsides

On the down side, functionally, the camera is nearly identical to the previous model and this means same basic shape and weight. Many people have moved on the Canon 5D Mk III in terms of smaller cameras and so moving back to the bigger body and weight with L series glass comes as a bit of a shock. Personally I still shoot with both a smaller A7s and my 5D Mk III so it is not an issue, but I know people who used to have 5D MKII or III who are surprised when they go back to the older form factor.

The camera records DCI 4K video internally, but disappointingly this requires a huge 1.74x crop factor. Canon have done this using the central portion of the camera’s 30.4 megapixel CMOS sensor. To get full-frame video you need to shoot in HD. In DCI 4K it records using the Motion Jpeg format at approximately 500 Mbps in 8-bit 4:2:2, and 4K frame rates are 29.97, 25, 24 and 23.98 fps. The camera has a CF and an SD card slot, but you’ll need a new very fast record card to shoot in 4K. There is external recording but external it is only HD – (1920x 1080) uncompressed YCbCr 4:2:2 8-bit.

While some will be keen on the most obvious upgrade in the Mark IV which is the significantly higher 30.4MP sensor, (a big increase in resolution compared to the MkIIl’s 22.1MP), I question how often 22.1 MP has not been enough in all the years I have been shooting with the MkIII. I have blown up images to A2 size and not had issues, I have cropped and used the imagery in most ways a VFX artist would want, and noise not resolution is the wall I hit. I actually slightly worry about the bigger file sizes 30MP will mean and how that will translate to filling up my Mac’s Flash drive while traveling.

RAW file size

  • RAW: 6270 x 4480 about 36.8MB
  • DPRAW: 6270 x 4480 about 66.9MB
  • M-RAW: 5040 x 3360 about 27.7MB
  • S-RAW: 3360 x 2240 about 18.9MB

It gets worse. With the Dual Pixel Raw mode the raw files are twice the size of normal, a mighty 72+ MB each. And Canon has not explicitly stated that Canon will licenses the technology to Adobe for Lightroom and Photoshop.