Metering
Canon introduced a new 63-zone Focus Colour Luminance (iFCL) metering system with the EOS 7D and this is also present in the EOS 550D. The new system uses two sensors to gather luminance and colour information, and this is claimed to make it more reliable by making it less influenced by red light. In its evaluative mode, the iFCL system also gathers information about the subject’s distance from the AF system.
In addition to evaluative mode, the EOS 550D has centreweighted, partial and spot metering, which can be useful, but occasionally I find the evaluative metering behaves in a similar way to centreweighted metering. As the iFCL system is linked to the selected AF point, it can make a difference where the AF point is positioned. I noticed that the exposure can change significantly depending upon the brightness of the subject beneath the AF point when the scene is the same.
Despite this issue, the evaluative metering is generally very good and using it usually results in the main subject being correctly exposed. It isn’t excessively distracted by bright or dark objects within the scene. However, as usual it pays to keep an eye on the histogram view, especially when shooting under overcast skies.
