My Canon 7d is about 2 months old. I used it for a shoot in DC, and it just isn't behaving as expected. When I try to focus, I get little black boxes in the focus frame. They used to be black, with the focal area in a red box. I let my girlfriend use the camera for a few hours, and I can't figure out what she's changed. Do I need to reset to factory settings? Or does anyone have an idea of how to tun my focus squares back to red, and to make them selectable?
What shows up in the viewfinder and when it shows up there is based on the cumulative results of several menu and custom settings on the 7D. Which mode you are shooting in, which AF mode, and which AF Area Selection you are using will all affect this. (To further complicate matters, there are two versions of the 7D instruction manual: The original 276 page version and a 292 page version released with firmware version 2.0.0. Since your 7D is only two months old we'll assume you have the newer version. It is also available for download here.)
Under Custom Function menu III: Autofocus/Drive (p.225ff) there are several settings you should check (these will affect the P/Tv/Av/M/B modes - Auto modes decide all the AF settings for you):
Which AF Area Selection mode (p.91) you are shooting in will determine which focus points are displayed in the viewfinder. If C.Fn III-9 is set to Disable only active focus points or zones will be displayed (p.229). The following is for One-Shot AF mode (p.89)(and AI Focus AF mode with Servo not active):
In AI Servo AF mode (p.89)(and AI Focus AF mode when Servo is active) the display is similar to the above:
Additionally, when Servo is active the green focus confirmation light at the far right of the viewfinder status information (p.19) will not confirm focus (p.89). As with One-shot AF mode, it will blink when no active focus points are in focus (p.89). Unlike One-shot AF mode, the focus confirmation light will not remain lit when any active focus points are in focus since in AI Servo AF mode the focus is not locked but continuously updated until the shutter is actuated.
Unlike previous Canon bodies such as the 50D or the 5D mark II, the 7D and newer Canon bodies do not have the focus points inscribed on the view screen with red dots that light up to indicate active focus points. If you think your 7D once did this, you are remembering using an older Canon body. Instead, the newer bodies use an LCD to superimpose the information onto the area covered by the view screen.