Live View displays and operation

Live view mode on the Canon EOS 5D Mark III works in a very similar way to the EOS 7D. There are separate live view and movie modes, selected using a switch next to the viewfinder. Once in Live View mode you can choose from a variety of views and AF methods. You can opt to use either the conventional phase-detection AF sensor (AF Quick) or the slower contrast detection method that uses the main imaging sensor. This second, 'AF Live' method is potentially more accurate and flexible (not being constrained to the 61 points of the AF sensor); it also has a face-detection option.

While the 'AF Live' and 'AF Live Face detection' AF modes are still significantly slower than the phase detect system in 'viewfinder mode' considerable improvements have been made over previous implementations of the system. You still get a lot of focus hunting but the system is definitely not prohibitively slow anymore and good to use at least in situations when focus speed is non-critical. The performance of the face detection system has improved as well. It's better now at detecting faces with glasses and from an angle. In out testing it reliably detected faces from almost a 90 degree angle.

But even if the improved live view AF performance cannot convince you, 'Live View only' features such as the on-screen magnification for fine-focusing, or exposure simulation to help judge image brightness, are genuinely useful and make Live View an invaluable tool for certain photographic application such as macro shooting or studio work.

Live View function settings

The most useful live view parameters such as exposure simulation, grid display and AF mode can be accessed and modified in the Live View tab of the shooting menu.

The Live View tab of the shooting menu

Live View display modes

Pressing the INFO button while in Live View toggles between the available display modes, each with differing levels of overlaid information. You can also enable optional gridlines.

No overlay Shooting settings
Full information Exposure information + histograms (luminance or RGB can be chosen in the playback menu)
A choice of three grids can also be overlaid on the live view image. These are selected using a menu option in the live view/movie tab of the record menu. Pressing the 'Q' button allows you to change the Auto Lighting Optimizer setting and the image size/quality.
All other settings can still be changed via direct-access buttons with full settings screens being overlaid on the live view image.  

Live View magnification and Digital Level Gauge

Just as in playback mode you can magnify live view by pressing the enlarge button to reach 5 or 10x magnification. While magnified you can use the multi-controller to move around the live image. Unfortunately as on previous Canon DSLRs you cannot magnify right out to the extreme corners.

The EOS 5D Mark III also has two accelerometers to offer a level gauge that shows pitch (up/down tilt) as well as roll (left/right tilt), overlaid onto live view image.

5x and 10x Live View magnification Digital Level Gauge

Exposure simulation

In the shooting menu you can optionally enable Live View exposure simulation mode where the Live View display will attempt to simulate the brightness of the final exposure. In this mode changes to exposure compensation or exposure (in manual mode) are simulated. If enabled you can also view the live histogram.

The 'During DOF preview' option is new on the EOS 5D Mark III. It allows you to 'switch on' exposure simulation while the DOF button is pressed. This is useful for quickly switching between standardized brightness for composition and exposure simulation for preview. Exposure simulation in combination with DOF preview is also the closest thing you get to a WYSIWYG preview of your shot.

Exposure simulation can be set in the Live View tab of the shooting menu and simulates the effects of exposure compensation or manual exposure on the LCD screen.