3Custom Function Settings
C.Fn4: Display/Operation
Focusing Screen
You can change the focusing screen to an Ec-series focusing screen more suited for your shooting. If you change the focusing screen, change this setting to match the focusing screen type to obtain the correct exposure.
Std.: 
Ec-CV
Standard focusing screen.
: 
Ec-A, B, D, H, I, L
For Laser-matte screens.
Since the Ec-A/B/I/L focusing screens have a prism at the center, the correct exposure cannot be obtained with evaluative metering or center spot metering. Use either center-weighted average metering or AF point- linked spot metering (except the center AF point).
Since the Ec-A/B/I/L focusing screens have a prism in the center, AF based on the color and facial information of a subject at the center of the viewfinder may not be achieved, even if [Auto AF pt sel.: EOS iTR AF] is set to [Enable] (p.95).
Although an Ec-C/CII/CIII/CIV/N/R/S focusing screen can be installed in the camera, the correct exposure will not be obtained. Use a commercially-available light meter to set a manual exposure or set exposure compensation and shoot.
The Area AF frame displayed on the Ec-CIII/CIV/N/S focusing screens is different from this camera’s AF Area.
To change the focusing screen, refer to the instructions that come with the focusing screen.