EOS-1D X on film:
Pt. 1 – Autofocus explained

EOS-1D X on film

November 2011

The Canon EOS-1D X DSLR features a completely new 61-point autofocus system to provide consistent focusing performance, no matter what the subject is or how bad the lighting conditions may be. The first of a series of six films about the capabilities of the EOS-1D X takes a closer look at the camera’s AF system – the most advanced autofocus system ever seen in an EOS DSLR.

In the film, European Professional Imaging Communications Manager Mike Owen explains some of the key features and benefits of the EOS-1D X’s 61-point Area AF system that includes 41 cross-type sensors and five dual-cross type AF points for extra precision. The film features Canon Ambassador, and top motorsport photographer, Frits van Eldik giving his first thoughts on the AF capabilities of the camera. He commented: "The 61-point system on the EOS-1D X is so quick and accurate, and has AF points spread over a wide field, that it allows you to focus very accurately."

The benefits of the new AF system include finer precision and increased AF tracking speed, increased low-light sensitivity down to EV -2 (the equivalent of shooting under the light of a full moon), faster predictive focus measurements, and the ability to adjust for any potential chromatic aberrations within the AF optics particularly when shooting under artificial lighting.

Autofocus modes are One-shot AF and AI Servo AF whilst for easier menu navigation and setting, all of the AF and AF Custom Function settings are now grouped into one dedicated AF menu tab. There are also six AF point selection modes in the camera – Automatic, Single Point AF, Single Point Spot AF (available with all lenses), Zone AF, and two AF point expansion settings.

The EOS-1D X’s AF system works in tandem with the camera’s autoexposure system that deploys a 100,000-pixel RGB metering sensor and a new metering algorithm. The sensor is used to detect a subject’s brightness, colour and face and, based on this, evaluative metering or evaluative flash metering is executed. This data is communicated to the AF system to assist with subject tracking.

An advantage of the increased focus sensitivity is the ability to detect extreme defocus and correct accordingly. By using the whole AF sensor, where every point is vertical line sensitive at f/5.6 or greater, the lens can be refocused much more quickly than before. The increased sensitivity of the focus system has also allowed for faster predictive focus measurements so that the EOS-1D X can begin predictive tracking as soon as a subject begins to move.

Six preset Case studies

There are six AF ‘Case studies’ preset within the EOS-1D X with an icon and example usage within the menu display to allow for optimisation of AF options.

Case 1 is for general purpose shooting that provides accurate and fast focus across a wide range of shooting situations.
Case 2 is designed for situations where the subject may move away from the AF point momentarily.
Case 3 allows you to instantly focus on subjects that enter the AF point area.
Case 4 is designed for subjects that change speed or direction rapidly.
Case 5 is designed for use with automatic AF point selection, Zone AF and AF Point expansion and subjects that move erratically, up and down or left and right.
Case 6 is for subjects that change speed abruptly and move erratically. Like ‘Case 5’ it is used with Automatic AF point selection, Zone AF and AF Point Expansion.