Canon T4i Performance

Generally good performance for a consumer SLR these days.

The Canon Rebel T4i turned in a reasonably fast startup time of well under a second, though shutdown was sluggish. (Automatic sensor cleaning which runs at power-up and power-down was enabled, by default.) The Canon Rebel T4i's buffer clearing times were quick with a fast UHS-I card.

The Canon T4i's mode switching times were quite fast; no complaints here.

The Canon Rebel T4i's full autofocus shutter response was a touch slower than average these days when using our standard single-point AF test, at 0.269 second. Interestingly, switching to Auto Selection AF and allowing the camera to choose the focus point reduced shutter lag to 0.112 second, which is very fast for a consumer SLR. As expected, enabling the built-in flash increased full AF lag, to 0.280 second. (The camera emits flash metering pulses and analyses the results before taking the final flash exposure.) In Continuous AF mode, shutter lag was a fast 0.111 second, though the subject may be out of focus in this mode. Shutter lag with Manual focus was very good, at 0.094 second. "Prefocusing" the camera by half-pressing and holding down the shutter button before the final exposure resulted in a lag time of only 0.074 second, which is very good for a consumer SLR.

The Canon Rebel T4i's AF lag time in Live View mode was quite a bit longer than using the optical viewfinder (as expected). We measured 1.07 seconds using "Quick Mode" (phase-detect AF) with Auto Selection. The T4i's new Hybrid AF in Auto Selection mode was noticeably slower than "Quick Mode" at 1.42 seconds, but switching to single point mode sped it up considerably to 0.833 second, though that's still pretty slow compared to using the optical viewfinder. Prefocused shutter lag in Live View mode was surprisingly fast at only 0.062 second, probably because the mirror is already up and out of the way in Live View mode.

To minimize the effect of different lens' focusing speed, we test AF-active shutter lag with the lens already set to the correct focal distance.

Since the type of lens used for focusing in Live View Hybrid AF mode makes a big difference to full autofocus shutter lag, we tested the Rebel T4i with a number of Canon lenses. As you can see, the new STM lenses are faster than some older lenses we tested, but these results are still much slower than most Compact System Cameras using only contrast detection, and also much slower than Sony's SLT cameras with full-time phase detection.

Shot-to-shot cycle times in the Canon T4i's single-shot mode were quite good for a consumer SLR, at 0.37 second for large/fine JPEGs, 0.34 second for RAW mode and 0.37 second for RAW + large/fine JPEGs.

Continuous mode speeds were also good for a consumer model, at about 4.8 frames-per-second for large/fine JPEGs, 5.1 fps for RAWs, and 5.6 fps for RAW + large/fine JPEGs. It's interesting that the camera was a little faster when RAW files were present.

Measured buffer depths in continuous mode were fair for large/fine JPEGs frames at 19 frames, but quite shallow when RAW files were included. We were only able to capture 6 RAW frames or 3 RAW + large/fine JPEGs before the frame rate slowed. (Note that in our cycle time testing we shoot a target consisting of a fine-grained digital noise pattern, designed to be very hard to compress. This gives us worst-case buffer capacity numbers for compressed files: You're likely to see greater buffer capacity when shooting more normal subjects.)

The Canon Rebel T4i's flash took an average of 3.3 seconds to recharge after a full-power discharge, which is pretty good.

Connected to a computer or printer with USB 2.0, the Canon Rebel T4i's download speeds were very fast.

Bottom line, the Canon Rebel T4i offers generally good performance for a consumer model. Buffer depth is quite shallow when shooting with RAW files, though, and the new Live View Hybrid AF system isn't nearly as fast as most CSC or SLT cameras.

Battery Life
Below average battery life for a lithium-ion SLR design.

The Canon T4i uses a custom rechargeable lithium-ion battery for power, and ships with a charger. Battery life is below average when using the optical viewfinder even for a consumer SLR, and of course Live View mode draws more power reducing battery life. We recommend you pick up a spare battery and keep it freshly charged and on-hand for extended outings.

The Canon T4i is however compatible with an optional BG-E8 battery grip, which can double capacity with two rechargeable lithium-ion battery packs. The grip also accepts AA batteries.

The table above shows the number of shots the Canon Rebel T4i is capable of (on a fully-charged rechargeable battery), based on CIPA battery-life and/or manufacturer standard test conditions.

(Interested readers can find an English translation of the CIPA DC-002 standards document here. (180K PDF document))