"Of the entirely new 61-point array, 41 points are cross-type AF sensors"
The EOS-1D X and EOS 5D Mark III share arguably the world’s most sophisticated AF system, with an entirely new 61-point array, and a host of configuration options that tailor it for nearly any professional photographer's needs. There are many new aspects of this terrific new AF system, so we'll discuss them in separate articles here on Canon's Digital Learning Center starting with the camera's AF points and area selection options.
Basic design goals of this new AF system are improved low-light AF performance, superior AF accuracy, and ability to achieve true high-precision AF with pro-grade f/4 lenses, such as the 24-105mm f/4L IS, 500mm f/4L IS and 600mm f/4L IS.
Number of points, and area covered:
The two cameras indeed have 61 AF points, the most ever in a Canon EOS SLR camera. But the new 61-point High Density Reticular AF is impressive not only for the sheer number of AF points, but for the way they’re laid-out, and the ways they can be used.
Side-to-side, the AF point array of these full-frame cameras covers a noticeably wider area of the viewfinder – nearly 53% of the horizontal width of the full-frame imaging area (vs. about 41% coverage on cameras like the EOS-1Ds Mark III and EOS 5D Mark II). The spread points is a full 19mm of the traditional full-frame 36mm image width. This added coverage makes it even easier to use outer AF points to focus upon off-center subjects. Top-to-bottom coverage remains at 8mm, the same as on the previous EOS-1Ds Mark III camera.
Much like the EOS 7D camera, the AF points are displayed in the viewfinder using a transparent LCD overlay. This allows great flexibility in what is displayed at any given time to the photographer. While details of this sophisticated viewfinder display will be explained in depth in a separate article, the important take-away here is that it opens the door to the tremendous range of options available in terms of how those 61 AF points are ultimately used.
Of the 61 AF points, 41 points are cross-type AF sensors (all the points in the taller center area, and the central ten, running vertically, in the shorter left and right point clusters). This surpasses the AF layout of competitive-brand SLRs with 51-point AF systems, where only the central 15 points offer cross-type design. Again, the characteristics of cross-type AF points will be covered in greater detail in a separate Digital Learning Center article.
Finally, with 61 densely-packed AF points, photographers who prefer to use a single AF point will find less likelihood than ever that there's no AF point right at their desired location. This can be especially significant to users who prefer to shoot with a tripod from time to time.
AF Area options:
It’s here that users really can experience the power of the 61-point High Density Reticular AF system in the EOS-1D X and EOS 5D Mark III. Like the previous EOS 7D camera, you're not limited to simply using a single AF point, or alternatively letting the camera automatically select the point for you. The size of the actual AF area used for focusing can be changed at any time, as follows:
- Single-point AF (manual selection)
This is the type of AF operation familiar to most serious shooters. Pick any one AF point, keep it upon your subject, and the camera uses that AF point – alone – to continue to read subject detail and focus upon it.
- Spot AF (manual selection)
First seen in the EOS 7D, you now take any one AF point, and reduce its size even further. This can be useful when the photographer really wants to pin-point the sharpest focus on a tiny part of a large subject, or shoot through foreground objects (such as tree branches and leaves, for instance).
- AF Point Expansion – 4 points (manual selection)
The opposite of Spot AF: instead of making a single AF area smaller, you now expand its size by adding four additional surrounding points (normally, the points above, below and to the left/right of the primary point you've selected). This gives a larger, moveable cluster of active AF points, and is especially useful if the primary, central point in the cluster suddenly sees a part of the subject with little detail or contrast.
New: AF Point Expansion – 8 points (manual selection)
An even larger, moveable cluster of AF points. A 3x3 square-shaped group of AF points, with eight points surrounding the primary user-selected point. Can be manually moved anywhere around the AF area, from center to any of its edges. Again, potentially very useful for subjects that may move unpredictably, or for instances where the primary AF point may occasionally pick-up plain, non-detailed areas of subjects.
- Zone AF (manual selection of zone location)
Select one of 9 available fixed clusters of AF points, with either 9 or 12 points grouped together, depending on whether it's centered or off-center in the 61-point array. Within that zone of active points, the camera will automatically focus upon the nearest detected subject, as long as it has adequate detail. This is different than AF point expansion, which relies on the user picking one primary point, and adding additional assist points surrounding it. Zone AF can be especially useful when there are a group of moving subjects, and you know you want to have sharpest focus on the closest one.
Automatic selection (all 61 points active)
Camera automatically chooses the active AF point(s), with all 61 points available. In One-shot AF mode (stationary subjects), camera will focus on nearest subject with adequate detail, similar to all previous EOS models with multiple AF points.
In AI Servo AF, as with the EOS 7D, user manually picks any one point as the starting point to track a moving subject; it can be centered or off-center. Once subject is being tracked, if it moves away from the starting point, other points will actively continue to track subject, and the viewfinder continually updates to show which AF points are active (this can be turned off if the shooter finds it distracting).
Memorize and instantly return to a pre-determined AF point
Navigate to any AF point (can also be Spot AF point, or an Expanded AF point), "register" (memorize) it, and then move to any other AF point or points and continue shooting. Press a configurable button, and the EOS-1D X or 5D Mark III instantly returns you to the memorized AF point.
The process is pretty simple: to memorize an AF point, be sure the camera's not set for Zone AF mode or Automatic AF point selection. Move the active AF point(s) to wherever you'd like to memorize, and press and hold down the rear AF point select button, and simultaneously press the ISO button button (EOS-1D X) or top panel illuminator button (EOS 5D Mark III). "HP" (Home Position) appears briefly in the finder, and the point is now memorized. Repeat the procedure to memorize a different point. (Only one location at a time can be memorized.)
To jump back to a memorized point, any of the buttons listed immediately below can be configured to switch to the registered AF point, using the camera's Custom Controls menu. Enter the Custom Control menu for any of these buttons, highlight an AF option, and you'll see "INFO - Detail set" on-screen. Press the INFO button, and in the resulting new menu screen, highlight the icon with "HP" and press SET to lock it in – you've now set that particular control to instantly return you to the memorized AF point.
- AF Start button
- AE Lock button
- Depth-of-field preview button
- Lens AF stop button (buttons on select Canon EF super-tele lenses only)
- Multi-function button 2 (EOS-1D X only)
Once you've configured any one of these controls to return you to your registered AF point, you're free to move to any other AF point and start shooting. Whenever you want to jump back to the AF point previously memorized, just press the appropriate button.
Automatic AF Area switching for horizontal and vertical shots
This was introduced in the EOS 7D camera, and carries over to the EOS-1D X and 5D Mark III. It's called "Orientation Linked AF", and it's activated via a setting in the fourth AF menu screen.
Once activated, you can select any of the 61 AF points (or any of the available AF Area options) with the camera held horizontally. Then, turn it vertically, and you can select a different AF point, or even a different AF Area mode (such as Zone AF for vertical shots, and Spot AF for horizontals).
Now, whenever the either camera is held horizontally, the point or AF Area you selected for horizontals will be active. And, when turned vertically, the camera will instantly change and select the point or AF Area you've pre-set for vertical shots. You don't need to press or turn anything (aside from the camera!).
This feature is ideal for users who quickly have to change compositions from horizontal to vertical, particularly for those users who want to go beyond simply using the center AF point all the time.
The EOS 5D Mark III and EOS-1D X are a lot more than just cameras with 61 AF points. Their innovative AF system allows photographers to begin to tailor it to their needs by managing those 61 focus points, changing not only the location but also the size of the active AF area. Whether the user wants to sample just a small area of a subject for precise focus, or use a wide area to accommodate unexpected subject movement, there are choices available to get the job done.
The AF points themselves cover a wider area of the picture than on any previous full-frame digital SLR camera, making it easier than ever to compose on subjects to the left or right of center.
While there’s certainly more to this AF system than its AF points, any understanding of the power of these two cameras has to begin with an appreciation of the options available to not only pick the point you want, but perhaps more significantly, quickly move to another point. From here, we can examine other important aspects of this stunning new professional AF system.