Canon announced the 5D Mark IV in August 2016 as the replacement to the popular Canon 5D Mark III, which dates from March 2012. The nearly four and half year gap between the two cameras meant that there were quite a few changes that were made to bring the new model up to speed and make it attractive to experienced photographers, but there was also a new and intriguing feature called Dual Pixel Raw.
What is Dual Pixel Raw?
Like the Canon 80D and Canon 1Dx Mark II, the 5D Mark IV’s CMOS sensor has a dual pixel arrangement. This means that each pixel site on the sensor is made up of two photodiodes which are slightly off-set.
Each of these diodes generates a signal which can be used to drive the phase detection autofocus system that operates in live view and video mode.
In the 5D Mark IV this dual pixel construction also enables new shooting mode called Dual Pixel Raw. When this mode is selected via the menu, rather than combining the signals from each photodiode pair, the 5D Mark IV records two images, each with 30.4 million pixels.
What’s different about Canon 5D Mark IV Dual Pixel raw files?
If you open a Dual Pixel Raw file in Adobe Camera Raw it looks just like any other raw file from the camera although it’s likely to be around 60+MB in size rather than the standard 35+MB.
However, when browsing images in Canon’s Digital Photo Professional (DPP) which is supplied with the 5D Mark IV, raw images shot in Dual Pixel Raw mode have DPR in the bottom left corner. If simultaneously captured raw and jpeg files are grouped together you see D+J.
More significantly, it’s possible to open the controls under Tools > Start Dual Pixel RAW Optimizer. This gives rises to three new types of adjustment, Image Microadjustment, Bokeh Shift and Ghosting Reduction. Only one of these adjustments can be applied to any image.
Image Microadjustment allows you to shift the position of maximum sharpness forwards and backwards along a scale running from Back 5 to Forward 5. It draws upon the fact the two images are shot from slightly different positions.
The results vary depending upon the lens and settings that you use, but the change is most obvious with longer lenses and wide apertures as depth of field is more restricted. It can be hard to see much difference as you make adjustments in DPP.
Bokeh Shift moves out-of-focus highlights horizontally. Again it can be hard to predict the impact, but it can be effective and make important parts of an image look sharper than they did originally. With some images I found using Bokeh Shift had more dramatic results than Image Microadjustment.
Ghosting Reduction is an ‘on’ or ‘off’ setting that’s worth trying if your image suffers from flare, but don’t expect dramatic results.
SEE MORE: Hands-on Canon 5D Mark IV review
Is Canon 5D Mark IV Dual Pixel Raw mode effective?
I shot a couple of autofocus calibration targets with the Canon 70-200mm f/2.8L IS II at f/2.8 and ran the image through DPP and Dual Pixel RAW Optimizer changing the Image Microadjustment settings a couple times. The first time I set the adjustment to Back 5 and the second Forward 5, both at the highest strength (10). Although the sharp area seems to move, it’s by a very tiny amount and there’s a more noticeable difference in some out of focus areas.
I’ve uploaded these images along with some real world shots to a Flickr gallery so you can download them and take a closer look at 100% if you like.
I also experimented with Image Microadjustment with several real world images, but was unable to detect any beneficial effect. In many cases applying an adjustment softened the subject at the focus point but it didn’t seem to sharpen anywhere either side. When making adjustments one step at a time, there sometimes doesn’t seem to be an effect and then when the next step is made, the sharpness seemed to drop quite noticeably.
In some cases using Bokeh Shift, however, had a noticeable impact on my shots. For example in a shot of a mushroom it’s made the image look a little sharper by addressing some of the blur around the white spots.
To answer the question, is Dual Pixel Raw mode effective, our experience suggests that in many cases, no. But don’t rule it out.
Canon 5D Mark IV Dual Pixel Raw mode summary
It’s clear that the impact of Canon’s Dual Pixel Raw mode is variable depending upon the subject, lens, exposure settings and shooting distance. However, we haven’t seen a significant benefit to using it in real world shooting situations.
Using it also eats up space on your memory card and decreases Canon 5D Mark IV’s maximum frame rate so for many people its not going to be worthwhile. If you’re shooting portraits with a very wide aperture it’s worth activating it and experimenting with it, but don’t expect dramatic results.