Camera Memory SpeedMemory Card Comparison & Performance Tests for Digital Cameras
Canon 70D SD Card Comparison
Published: January 6, 2015
The Canon 70D offers a 20.2 MP APS-C sensor in a versatile DSLR format. The 70D uses a DIGIC 5+ processor and can provide up to 7 fps continuous shooting. Its unique dual-pixel AF system and articulating screen add versatility.
To compare memory card performance in the in the 70D, 32 different SD cards were tested. The 70D supports UHS-I SD cards. All cards tested support UHS-I (the UHS-II cards are backwards compatible and operate in UHS-I mode in the 70D). Results are presented in the following tables. The first table shows write speed and is the most direct way to compare card performance. The second chart compares continuous shooting results, a measurement of how many shots can be taken in 30 seconds with different image settings. A brief analysis follows and fastest and best value SD cards for the 70D are recommended at the end.
Canon 70D Card Speed Test Details
- Camera: Canon EOS 70D
- Test date: December 18, 2014
- Firmware version: 1.1.1
- Image file size in tests:
- RAW: 30.9 MB
- JPEG (Large, Fine): 12.4 MB
- Each card formatted using "low-level format" in camera
- Camera settings:
- ISO 100
- manual exposure
- 1/60 shutter speed
- custom white balance
- standard picture style
- auto lighting optimizer disabled
- long exp. noise reduction off
- high ISO speed NR off
- highlight tone priority off
- image review off
- lens aberration correction disabled
- continuous shooting drive mode
- WiFi disabled
The tests are conducted with the 70D on a tripod, aimed at a detailed scene under controlled lighting. Focus is set manually using Live View at 10X magnification. A remote release timer is used to provide 30 second intervals for continuous shooting. A video recording is made of the card access light and reviewed to determine the exact write time. The total size (in bytes) of images written to the card divided by the actual write time (in seconds) provides the average write speed in bytes per second. Results are provided in megabytes per seconds (MB/s) where 1 MB = 1,048,576 bytes. The write speeds below are for RAW image mode (RAW+JPEG and JPEG modes provide lower write speeds).
Write Speed
36.4Continuous Shooting
The continuous shooting results show the number of pictures the 70D can take in 30 seconds. The test is conducted in three image modes: RAW+JPEG, RAW, and JPEG. JPEG mode is Large, Fine. When the test beings, the camera is able to shoot at full frame rate while it buffers the initial images. The camera begins to write to the card almost immediately, however the rate of data from images being taken is greater than the speed it is able to write to the card. At some point the buffer reaches capacity and the camera prevents further shooting until the buffer has cleared enough space for more images. Slower memory cards can cause the buffer to fill sooner and cause a significant drop in frame rate after the buffer has reached capacity.
Camera settings affect the rate and number of images that will fit in the buffer, however the image subject also affects the results. Detailed subjects create larger files. Large files require more time to write to the card and decrease the number of images that can be taken in the 30 second interval. A consistent setup is required to assure accuracy. A detailed test scene is used for this test to show the difference between cards, rather than a test that aims to find some maximum number of images possible (such as taking a burst of images with the lens cap on).
70D Performance Analysis
Although the Canon 70D supports UHS-I cards, it does not support SDR104 mode (104 MB/s bus speed) and is limited to 50 MB/s bus mode. Protocol overhead, writing separate files and limitations in the 70D reduce the measured write speed, resulting in a 36.4MB/s maximum average write speed. While many SD cards are capable of higher write speed, the 70D is the major limiting factor. Some cards perform better than others, but several measured around the 33-35MB/s write speed range in the 70D. Spending more for a card capable of 80-90MB/s write speed yields little benefit in the 70D.
In the continuous shooting test, the 70D took the first 7 RAW+JPEG shots before the frame rate dropped. The frame rate after the buffer filled varied between 0.5 and 0.9 frames per second in this test; faster cards provided a higher frame rate after the buffer filled. In RAW mode the camera would capture 12 to 13 shots before the frame rate dropped to between 0.5 to 1.2 frames per second. In JPEG mode the 70D got between 20 and 27 shots at full frame rate before dropping to between 1.2 to 2.9 frames per second for the remainder of the 30 seconds. Faster cards were able to capture more shots and shoot at a higher frame rate after the buffer filled. In continuous shooting the number of shots and the frame rate depend on many factors: camera settings, card speed and image subject. The detailed test scene used in this test produced 30.9MB RAW files and 12.4MB JPEG files.
Similar to the Canon 6D, certain cards tended to provide better results in the 70D. SanDisk and Kingston cards generally provided the best performance in this camera, while the Samsung PRO and Toshiba Exceria Type 2 cards performed well below what one might expect given their excellent performance in other cameras. Samsung PRO cards provided below average results in JPEG burst shooting in the 70D, similar to the their lackluster performance in the Canon 6D.
Recommended SD Cards for the Canon 70D
SanDisk Extreme 60MB/s Card
The fastest card for the Canon 70D is the SanDisk Extreme Pro 95MB/s UHS-I. This card has been faster than every other card in nearly every camera it has been tested, although in the 70D the margin between it and the next dozen or so cards is narrow.
When cost is taken into consideration, SanDisk Extreme 60MB/s SD cards provide nearly the best performance in the 70D at a lower cost. Earlier (now discontinued) SanDisk Extreme 45MB/s cards provide similar performance in the 70D, but the updated 60MB/s version supports faster read and write speeds. The Kingston Class 10 UHS-I 64GB SDXC card provides excellent performance at a low cost, as well as an ultra-fast read speed (up to 97MB/s sequential read in benchmark tests).
Transferring images from the Canon 70D
The USB 2.0 port in the 70D can be used to transfer images directly from the camera. USB 2.0 typically provides up to 35MB/s transfer speed, but the actual USB transfer speed of the 70D measured only 25 MB/s. Transfers were performed by copying RAW files from the fastest card in the 70D, the SanDisk Extreme Pro 95MB/s UHS-I.
When the same files were copied from the card using an external USB 3.0 card reader, the actual measured transfer rate was 90 MB/s. Further memory card reader information and tests can be found in the Card Reader Reviews.