EOS-1D X on film:
Pt. 3 - AE system explained

EOS-1D X on film

November 2011

The Canon EOS-1D X DSLR features an all-new AE system to deliver accurate exposures in every frame the camera shoots. The third of a series of six films about the capabilities of the 18.1 Megapixel EOS-1D X examines the camera’s AE system and explains how it operates.

In the film Canon Europe’s European Professional Imaging Communications Manager, Mike Owen, explains the features and benefits of the EOS-1D X’s AE system. He reveals: “It has a 100,000-pixel sensor that’s divided into 252 zones for metering – when you compare that to the 1D Mark IV, with its 63-zone metering system, you’ll notice a real difference in the images you’ll be able to get with this camera.”

The EOS-1D Mark IV's metering system used black and white metering sensors but the EOS-1D X’s sensor is an RGB colour sensor that is able to measure not only light levels, but it can also detect colour information and the presence of a face within the frame. Because the metering sensor captures RGB data, it is able to calculate the colour of the scene. Thus it can provide colour-tracking information to the AF system and face detection data both for AF and Auto Scene detection.

The sensor is especially aware of green and yellow as these colours can adversely affect the exposure reading and cause over- or under-exposure respectively. By using the colour data and information from the camera’s 61 AF points, the EOS-1D X is able to detect where in the frame the subject is and then bias the exposure accordingly to ensure the best exposure setting. This provides more stable and accurate exposures than have been seen before in a Canon EOS SLR.

Dedicated DIGIC 4 processor

The EOS-1D X’s metering system has a dedicated DIGIC 4 processor to cope with the vast amount of exposure data it is receiving and to ensure that this data is processed very quickly. The camera’s metering modes include evaluative, partial, spot and centre-weighted. Spot metering options are centre spot metering, AF point-linked spot metering, and multi spot metering.

Distance information is fed directly into the lens from the from the EOS-1D X’s metering system – this enables the camera to be able to look at where the subject is in the frame, and the distance it is away from the camera, to make sure that exposure is accurate in every frame.

The 252 metering zones are also used for flash metering, allowing for more precise subject location based on pre-flash readings. In low ambient light conditions, where some zones may receive little or no light which therefore could potentially lead to inconsistent exposure, the sensor enlarges each zone so that it meters from 35 zones.

The colour and face detection system is also used in the E-TTL II flash metering algorithm. By locating a face within the frame, the EOS-1D X can accurately adjust the flash output to ensure that the face is correctly exposed, while ignoring any reflective objects within the frame that may otherwise lead to inaccurate flash exposures.