Well, the brouhaha over the next generation 5D is significant, and relentless. Perhaps this shouldn’t be such surprise as the 5D has carried with it a badge of honor, of innovation, of capability from the first and second generations. It remains today the most common camera I come across when speaking to professional working photographers. Whether it is so deserved is another story, especially given the relative lack of scaled-improvement in the MK3, but since the MK IV ‘spec sheet’ has been leaked, there’s been mixed reception.

On the one hand it appears to be a ‘keeping up with the Jonses’ release – more market matching than surpassing. But that’s all being overshadowed by the main marketing tool, the Dual Pixel Raw. Except, we don’t quite know what that is, nor what it does.


The info seemed to have been leaked on the site Nokishita, and numerous people have done rough translations of it to come up with the following:

Pixel RAW Dual: record both of one of the normal to the RAW file of the image and the parallax information (parallax information). Digital Photo Professional of the “Dual Pixel RAW Optimizer” in the can: three of image processing
Image Micro-adjustment: by using the depth information, to fine-tune the maximum position of the sharpness and resolution (original: micro-adjusts the position of maximum sharpness and resolution)
Bokeh Shift: to change the position of the previous blur of viewpoint (original: repositions the viewpoint of foreground bokeh for a more pleasing result)
Ghosting Reduction: reduce the incidence of ghost and flare
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

Now, this isn’t the first time, nor the second, nor the third that Canon has dabbled with dual pixel tech, as the 70D, 80D, and 1DX MK II all have dual pixel Autofocus, which is essentially a phase-difference detection AF on the image sensor plane. In this scenario each pixel is made of two different photodiodes that can capture light independently of the other. Each detects the signal seperately which allows them to be combined and used together. When the image is shot they output the signal as a single pixel. The variance between the two signals is calculated and that drives how much the lens moves. This, however, doesn’t seem to be how the new dual pixel raw will function.


*See this Canon PDF on Dual Pixel AF

Just from the leak information it would appear that rather than just processing the signals and measuring the difference, perhaps both photodiode readings would be recorded? The DPRAW size above hints at that anyway. And of course all of this harks back to the Lytro cameras, which did have multiple photosites behind each micro lens, but this seems to be to a much smaller extent. If that is the scenario, it would appear that what this might enable a user to do is adjust focus a minute amount by mapping the depth of the image a bit.

A minute amount, however, could mean a lot to some people. Wedding photographers who may want to pull a member of a group shot into the focal plane if they’re just outside of it, and any studio photographers who shoot shallow know so many great shots are unusable because the focus is just off on the face, and this could potentially save that; maybe bring back into focus an eye that’s just off. How incredible would that be?

[REWIND: The Canon 5D MK IV Has Been Leaked & This Seems To Be It]

Of course, the leak even suggested this was to be done in post, and that may be where the biggest issue with all of this currently lays. Something quite so complex and perhaps proprietary suggests it would likely only be able to be used with special software that would likely be Canon-specific. That means there would be significant waiting periods before the bigger names like Photoshop, Lightroom, Capture One and so on manage to re-work their applications to allow for this feature – IF they do it at all, because they’d likely want to see it proven valuable first.

Again, this is all speculation, but what fun is a market if you can’t make an educated but wildly-reaching hypothesis? Either way, we’ll likely find out very soon as the MK IV marches ever close to the precipice of its release.

Sources: Nikishita, CanonWatch, Canon Technical