Canon T3i Live View

Canon EOS Rebel T3i Live View

Like most SLRs these days, the Canon T3i features a Live View mode for its rear-panel LCD monitor. The Live View mode lets you use the LCD monitor as a large viewfinder, and offers an exposure simulation function which attempts to display the expected outcome of your chosen exposure settings. A dedicated Movie / Live View button is used to activate or disable Live View mode on the Rebel T3i, and the function is available in all still image shooting modes. (In Movie mode, the live view feed cannot be disabled, and the same button instead acts to start or stop movie recording.)

The Canon T3i's Live View mode feature set is comprehensive, and the display offers a lot of information such as current settings, exposure, and composition aids (see illustration below, courtesy of Canon USA). As compared to the T2i's overlay, the T3i offers much the same information, with the only addition being an Eye-Fi card transmission status indicator. Some indications have been rearranged, however.

The Canon T3i groups settings related to Live View shooting in Record Menu 4, a much more logical location that that used by older Rebel-series models such as the T2i, which hid these options in a separate Live View / Movie menu accessed through Setup Menu 2. There's still a little possibility of confusion though, since several options are duplicates of those in the Movie menus, and so if they're changed in one menu, the equivalent variable will have changed on return to the other menu. The Live View mode also includes a greatly abbreviated equivalent of the Quick Control menu screen that's available when shooting using the viewfinder, accessed using the rear-panel Quick Control button. Instead of filling the screen, it is shown as a single column of icons at the left of the LCD display, and allows adjustment of AF mode, Drive mode, White Balance, Picture Style, Auto Lighting Optimizer, Image Quality / Size, and Built-in Flash Function settings, as well as selection of the active AF point if using Quick mode autofocus.

A nice feature of Canon's Live View mode is that it doesn't immediately stop the live view feed when you enter the camera's menu system, or switch between operating modes. Some rival cameras will immediately terminate the live view stream and drop the camera's mirror in either instance, causing unnecessary wear and tear on the mirror and shutter mechanisms if you were intending to immediately continue live view shooting.

The T3i's Live View mode offers three autofocus modes, selected through the Live View function settings screen or Quick Control menu: "Quick mode," which employs the camera's dedicated phase-detection sensor, as it would when using the optical viewfinder, plus two contrast-detection autofocus types--"Live mode" and "Face Detection Live mode"--which both operate on data streamed from the image sensor itself. Face Detection Live mode can detect multiple faces in the frame, but only selects (and indicates) one face on which the camera will set focus and exposure. The selected face can be changed by pressing the left and right arrow keys to jump through the detected faces in either direction. The contrast detection modes are slower than phase-detection focusing, but don't require the mirror briefly drop to redirect light to the phase-detection AF sensor, which interrupts the live view display in Quick mode. The contrast detection modes can also be more accurate, and allow the AF point to be positioned anywhere within the image frame (except for the extreme edges), rather than being limited to the T3i's nine fixed AF points. On the flip side, Quick mode AF can be noticeably faster, even when taking account of the time to cycle the mirror, especially when shooting in low-light or with low-contrast subjects. Quick mode is also better suited to moving subjects, which can make it challenging to achieve a focus lock using contrast detection AF.

The point(s) at which a focus lock was achieved in Quick mode AF are indicated on the live view feed with a green focus point indication immediately after the live view feed resumes, since the feed must be briefly interrupted during focusing. Alternatively, you can bring your eye to the viewfinder during the AF operation. Even though you're framing images using the LCD display, the viewfinder becomes visible with the mirror dropped for focusing, and the active AF point(s) are still indicated for the brief time that the optical view is available, perhaps letting you judge whether to trip the shutter just slightly earlier. Manual focus is also supported in live view mode, and includes either 5x or 10x image magnification to assist.

In Live View mode, evaluative metering is always used to determine correct exposure, though exposure compensation is available. The Exposure Simulation function will attempt to recreate the exposure level that would be obtained with your current settings on the LCD display. This may raise noise levels of the live view feed beyond what could be expected in the final image, since it must operate with a fast enough shutter speed to achieve its required refresh rate. The aperture also remains open by default, and so the exposure simulation doesn't indicate the areas in focus unless you configure the Set button to provide depth-of-field preview, and then hold it down during live view. Exposure Simulation will attempt to continue even with depth of field preview active, though this may raise the live view noise levels even further. If you pass outside the range where the live view feed can simulate your exposure, the "Exp. Sim" icon near the bottom right of the LCD will blink, as a warning. Unlike in more sophisticated Canon SLRs, you can't disable exposure simulation, and so there's no way to obtain a clear live view feed with which to judge focus and framing, without being shown the effect of your exposure variable choices.

You can enable one of two different overlays, which divides the screen with either a 2x2 grid, or a 5x3 grid, useful for precise image framing. You can also select one of four different aspect ratio settings for JPEG still images through the menu. (Raw images are also tagged with the aspect ratio, but the original aspect can be accessed if desired, and not all software will necessarily recognize the aspect ratio tag.) Available aspects include the native 3:2, plus 4:3, 16:9, and 1:1. Blue lines on the LCD specify the edges of the crop area, but the full live view feed is shown, so you can use this area to assist in framing your image.

You can also specify how long the camera's metering system should remain active without user interaction, within a six-step range from four seconds to thirty minutes. It's overruled by the Auto Power Off function, so whichever timer is shorter will apply. Also, Live View shooting can be disabled altogether if you don't use it, preventing the mode being accidentally triggered by bumping the Movie / Live View button.

The EOS Utility software (included with the camera) allows you to shoot remotely via USB connection while viewing the Live View image on your computer. You can also display the Live View image on an HDTV with an optional HDMI cable, or on standard-def displays via the included composite video output cable.

The Canon T3i comes equipped with a temperature sensor, and if the internal temperature exceeds an undisclosed threshold, Live View will be disabled to protect internal circuitry from overheating. A high temperature icon is displayed on the LCD monitor to warn the user that image degradation may be occurring, and that the camera may disable Live View until normal operating temperature is restored.

Like a larger version of the optical viewfinder display, the Live View display reports the exposure information along the bottom of the screen, with additional settings and information overlaid to the left and right, as well as the selected focus area(s). The amount of information displayed can be varied by pressing the INFO button, toggling through four display modes -- image only, image plus basic exposure information, image plus detailed exposure information, and finally image plus detailed exposure information alongside either an RGB or luminance histogram.