Ever since the 7D Mark II was announced, the big question on my mind has been "How does the 7D Mark II AF system compare to the best-ever-prior AF system found in the 1D X and 5D Mark III?"
The 1D X and 5D Mark III AF systems are easily the best I've ever used and my in-focus hit rate when using these cameras, especially with subjects in motion, has never been higher. Then the 7D Mark II was announced with even more focus points (including a higher number of cross-type AF points) and many of the same or even improved AF features found in the 1D X/5D Mark III.
In response to this question, Chuck Westfall (Advisor, Technical Information, Canon USA) was gracious enough to prepare a detailed technical comparison for us. Chuck's information is a must-read for anyone choosing between these three DSLRs:
EOS 7D Mark II vs. EOS-1D X and EOS 5D Mark III TTL-SIR (Through The Lens Secondary Image Registration) AF Systems Comparison
© 2014, Chuck Westfall/Canon U.S.A., Inc.
Now that the EOS 7D Mark II has been introduced, there is a great deal of interest in the comparison of its through-the-viewfinder autofocus (TTL-SIR AF) system performance versus the EOS-1D X and EOS 5D Mark III cameras. Although there are many similarities between all three cameras in terms of AF performance, there are also many differences. Please review this document for further information.
The 65-point AF system of the EOS 7D Mark II covers a much larger percentage of the picture area than the 61-point AF system of the EOS-1D X and EOS 5D Mark III. This is mostly due to the smaller image sensor of the EOS 7D Mark II, but the net result is that it’s possible to autofocus off-center subjects closer to the edges of the frame with the EOS 7D Mark II than the EOS-1D X or EOS 5D Mark III. Advantage: EOS 7D Mark II
Cross-Type AF Points and AF Precision
There are several differences between the AF systems of the EOS 7D Mark II and the EOS-1D X/EOS 5D Mark III in terms of cross-type AF points and AF precision.
AF Area Selection
The EOS 7D Mark II is similar to the EOS-1D X and EOS 5D Mark III in terms of the range of AF Areas that can be selected, such as Single Point Spot AF, Single Point AF, 4-point AF Point Expansion, 8-point AF Point Expansion, Zone AF, and Automatic AF Point Selection. However, the EOS 7D Mark II adds a new feature called Large Zone AF, and it also has a new control on the back of the camera called the AF Area Select Lever that makes it easier to change the AF Area without removing your eye from the viewfinder. Advantage: EOS 7D Mark II
The center AF point on the EOS 7D Mark II can function in light levels as low as EV - 3 in One-Shot AF, versus EV -2 for the EOS-1D X or EOS 5D Mark III. Advantage: EOS 7D Mark II
AI Servo AF Characteristics
All three cameras use the same AI Servo AF algorithms (i.e., AI Servo AF III), and all three use a similar system for setting AI Servo AF characteristics, based on a menu structure with 6 customizable “Case" scenarios. Each case can be customized in terms of AF Tracking Sensitivity, Acceleration/Deceleration Tracking, and AF Point Auto Switching. However, the EOS-1D X with current firmware (version 2.0.3 or later) offers a choice of 5 settings each for Acceleration/Deceleration Tracking and AI Servo 2nd Image Priority, versus 3 settings for these parameters on the EOS 7D Mark II and EOS 5D Mark III. Advantage: EOS-1D X
There are two distinct aspects to AF Speed that need to be compared individually: AF calculation vs. lens drive speed. Both of these parameters have a bearing on total system speed.
iTR AF (Intelligent Tracking & Recognition AF)
Canon introduced iTR AF with the EOS-1D X in 2011. This system takes advantage of the camera’s 100,000 pixel RGB metering sensor to supply face detection and color data to the AF processor. When the 1D X is set for either Zone AF or automatic AF point selection using all 61 AF points and the iTR AF system is engaged, the camera’s AF processor cross-references face detection and color data to the phase detection AF data. This enhances the camera’s ability to track subject movement within the active AF area. iTR AF is effective for both One-Shot AF and AI Servo AF.
iTR AF is unavailable with the EOS 5D Mark III because that camera uses a simpler 63-zone dual-layer metering sensor without face detection or RGB color detection. But the EOS 7D Mark II has a new 150,000 pixel RGB + IR Metering sensor, and uses it to provide iTR AF that is even more sophisticated than that of the EOS-1D X. Again, please note that iTR AF is only effective when multiple focusing points are active. Advantage: EOS 7D Mark II
AF Point Illumination in the Viewfinder
The EOS 7D Mark II and EOS-1D X are essentially equivalent in this comparison, but the EOS 5D Mark III does not illuminate the active AF point during AI Servo AF. Advantage: EOS-1DX and EOS 7D Mark II
Orientation-Linked AF Point Selection
All three cameras are the same in this area. Advantage: Draw
Spot Metering Linked to AF Point
Only the EOS-1D X offers this feature. Advantage: EOS-1D X
The new EOS 7D Mark II delivers several significant improvements compared to the EOS-1D X and EOS 5D Mark III, including a wider coverage area, more cross-type AF points, better low-light sensitivity, and easier AF Area selection while looking through the viewfinder. But the EOS-1D X and EOS 5D Mark III still rise above the EOS 7D Mark II in terms of the number of high-precision dual cross-type as well as high-precision conventional cross-type AF points. The EOS-1D X and EOS 7D Mark II are superior to the EOS 5D Mark III in terms of lens drive speed with current and recently discontinued EF super-telephoto lenses. The EOS-1D X is superior to both the EOS 7D Mark II and the EOS 5D Mark III in terms of the range of some AI Servo performance parameters, and the ability to link spot metering to the active AF point.
The relative value of each of these features will vary according to the type of photography being done as well as the lenses in use and the personal preferences of the photographer. Therefore, it’s not possible to state with certainty that the performance of any of these cameras is universally superior to the others, even when limiting the discussion to through-the-viewfinder AF systems (i.e., TTL-SIR AF).
Our best advice is to consider all of the options before coming to any conclusions.
Back to the Review
I would like to personally thank Chuck Westfall very much for the time and effort he put into preparing this information for us. I hope that any missing decision-making factors are now clarified in your mind.
Return to the Canon EOS 7D Mark II Review page for much more information.
1 The list of current EF super-telephoto lenses capable of enhanced drive speed with the EOS-1D X includes EF200mm f/2L IS USM, EF300mm f/2.8L IS USM, EF300mm f/2.8L IS II USM, EF 400mm f/2.8L IS USM, EF 400mm f/2.8L IS II USM, EF400mm f/4 DO IS USM, EF400mm f/4 DO IS II USM, EF500mm f/4L IS USM, EF500mm f/4L IS II USM, EF600mm f/4L IS USM, EF600mm f/4L IS II USM and EF800mm f/5.6L IS USM. Drive speed for other current EF lenses is the same for all three cameras (EOS-1D X, EOS 5D Mark III and EOS 7D Mark II).