Published: June 7, 2017
The Canon Rebel T7i (800D) camera is an update to the Rebel T6i/T6s. The T7i has a 24.2MP megapixel APS-C sensor with a new AF system that incorporates 45 cross-type sensors for auto focus using the optical viewfinder, while on-sensor Dual Pixel using phase detection enables fast and accurate focusing in Live View and video. The T7i uses the latest DIGIC 7 image processor captures accurate images with ISO range from 100 to 25,600. The T7i offers up to 6 frames per second continuous shooting, up from 5 frames per second in the T6i/T6s. A single SD card slot supports UHS-I cards.
The T7i was tested with 125 SD cards. Results are provided in average write speed for continuous shooting RAW images. Additionally, continuous shooting results show the number of images captured in 30 seconds for RAW+JPEG, RAW and JPEG images. An analysis follows with information observed from testing. Recommended SD cards for the T7i reveal the fastest and best value memory cards for the camera.
The tests were conducted with the T7i secured on a tripod using a remote release timer to actuate the shutter. The timer provides consistent 30 second intervals. A detailed test scene with controlled lighting is used.
Write speed is determined during the buffer full condition which begins when the buffer has reached capacity and is unable to sustain the full frame rate. The interval between shots is limited by the rate at which the buffer is emptied which is determined by the write speed of the card. The total bytes written divided by the total time gives the average write speed. Results are presented in megabytes per second, where 1MB = 1,048,576 bytes.
The continuous shooting results show the number of pictures taken in 30 seconds not including the buffer clearing time. The modes include RAW+JPEG, RAW, and JPEG. The JPEG setting is large, high quality. The T7i is set to continuous high drive mode. The detailed test scene produces 34.0 MB RAW files and 12.8 MB JPEG files.
The Canon T7i supports UHS-I SD cards. It is capable of SDR104 mode that can reach up to 104MB/s bus speed. While UHS-II cards are included in this test, the cards only work in UHS-I mode and offer little benefit over a fast UHS-I card in the camera. In devices that support UHS-II, the cards have an advantage in speed and offer up to three times the transfer rate of UHS-I cards.
The T7i has an increased buffer size over the T6i/T6s. Its buffer and write speed are practically identical to the 77D. With the detailed test scene, the T7i captured up to 26 shots in RAW mode at full frame rate before the camera was limited by the write speed of the memory card. Using a slower card resulted in fewer shots at full frame rate, and the slowest cards only reached 18 RAW shots before slowing. The frame rate with the buffer full varied between cards. The fastest card could sustain 2.4 fps with the buffer full while the slowest card could maintain less than 0.4 fps. The image size affects these numbers with less detailed subjects creating smaller files and higher effective frame rates with the buffer full.
Shooting RAW+JPEG, the T7i captured between 17 and 22 shots at full frame rate before the frame rate was reduced. With the buffer full the camera continued to shoot at 0.1 fps with the slowest card up to 1.7 fps with the fastest. When set to JPG image mode the T7i was not limited when using with fast cards, while slower cards began to limit the number of shots. The slowest card captured 29 JPEG images at full frame rate, after which the camera was limited to 1.1 fps. These numbers change with file size, but you should expect at least as good performance when shooting images that have an average amount of detail.
The fastest cards for the Canon T7i are Sony SF-G 300MB/s UHS-II and Lexar Professional 2000x UHS-II cards. While these are UHS-II cards, the T7i only supports UHS-I and the cards revert to UHS-I mode in the camera. The advantage of UHS-II cards is fast transfers from the card to a computer, offering up to 300MB/s read speeds. However, the performance of the fastest UHS-II cards comes at a price. There are UHS-II cards with lower write speeds that still exceed the maximum speed the 7Ti can support. For example, the Sony M Series UHS-II cards offer all the speed necessary for the T7i as well as the faster read speeds enabled by UHS-II for quick downloads to a computer.
When cost is a factor, fast UHS-I cards like the SanDisk Extreme Pro 95MB/s UHS-I cards offer nearly the same performance in the T7i at a much lower cost. An alternative to the SanDisk card is the Kingston U3 90/80 MB/s UHS-I that has good performance at a slightly lower price.
The T7i includes a USB 2.0 port on the camera that can be used to download images. Using the SanDisk Extreme Pro 64GB SDXC card and copying 3GB of RAW images from the camera to a computer with a SSD drive, the transfer averaged around 31MB/s. This is good performance for USB 2.0, but well short of what can be achieved with a USB 3.0 card reader. In a separate USB 3.0 card reader, UHS-I cards such as the SanDisk Extreme Pro 95MB/s provide actual download speeds of about 90 MB/s. UHS-II cards like the Lexar Professional 2000x UHS-II can reach around 250 MB/s when copying actual RAW files. Further card reader tests and benchmarks can be found in the Card Reader Reviews.