Published: October 25, 2018
The Canon EOS R is a 30.3 megapixel mirrorless full-frame digital camera. The EOS R uses Canon's Dual Pixel AF with over 5,000 selectable focus points. A new 54mm diameter internal flange mount was developed for the mirrorless camera and three adapters are available to mount EF and EF-S lenses that support all lens functions. An electronic OLED viewfinder provides 100% coverage and 0.76x magnification, while a 3.15-inch articulating LCD screen allows unlimited shooting angles. The EOS R uses the latest DIGIC 8 processor and is capable of up to 8 fps continuous shooting.
The EOS R has a single card slot that supports UHS-II SD cards and also works with UHS-I and standard SD cards. A total of 113 SD cards were tested in the EOS R to evaluate write speed. Maximum write speed for continuous shooting was calculated using each card. More information about the camera's performance and buffer capacity is detailed in the analysis, or you can skip right to the fastest SD cards recommended for the Canon EOS R based on the test results.
The Canon EOS R is mounted on a stable tripod and actuated by a remote release timer. The image subject is a detailed test scene illuminated by controlled lighting. A manual lens is mounted on the EOS R using the Canon Mount Adapter EF-EOS R and all manual settings are used to provide shot-to-shot consistency.
Write speed is determined using the buffer full condition. This begins when the buffer has reached capacity and the camera is unable to sustain the full continuous frame rate. In this condition shooting is limited to the rate at which the buffer is emptied. During the buffer full condition the total data written is known in addition to the time between shots. This method eliminates the need to use the card access light. Because the interval between shots is not constant for this camera, an extended test time of one minute is used for each card. A regular pattern in the shot intervals is observed and the first and last shots are chosen according to the repeating pattern. This minimizes the effect of arbitrary start and end times given the irregular intervals. The total bytes written during the selected interval divided by the time gives an average write speed. The fastest 30 cards were tested twice and the results averaged. Results are in megabytes per second, where 1MB = 1,048,576 bytes.
The Canon EOS R supports UHS-II SD cards which theoretically operate up to 312 MB/s. The highest average write speed during continuous shooting was 182.7 MB/s. The camera is also compatible with UHS-I cards and supports SDR104 (up to 104 MB/s). The fastest UHS-I cards averaged up to 75.6 MB/s write speed in the EOS R.
Card | Buffer Capacity in shots vs file size (different image subjects) | ||
---|---|---|---|
27.0 MB RAW | 37.1 MB RAW | 50.0 MB RAW | |
Adata Premier One UHS-II 64GB | 61 | 46 | 28 |
The EOS R has a generous buffer. Using the fastest UHS-II cards and a detailed image subject that produced 50 MB RAW files the camera could capture between 28-30 images at full frame rate. The full frame rate of the EOS R was just under 8 fps. Slower UHS-II cards such as the Lexar 1000x, ProGrade 200 MB/s and Sony M Series cards dropped the number of shots to 21 at full frame rate. Using UHS-I cards the buffer capacity was between 19-21 shots. These numbers are for a rather large 50 MB RAW file size which the highest average write speed of up to 182 MB/s.
Using a different test scene that produced 37 MB RAW images, the buffer capacity was up to 46 shots with the fastest UHS-II cards and between 26-30 shots with UHS-I cards. With this file size the highest average write speed was up to 161 MB/s. Changing the image subject to one with less detail and large out of focus areas produced 27 MB RAW files and resulted in a 61 shot buffer capacity with the fastest UHS-II cards. Different image subjects and levels of detail create different file sizes and has an impact on buffer capacity. The camera is writing during continuous shooting and the buffer capacity varies with card write speed: faster cards allow the buffer to clear faster and increase the number of shots at full frame rate.
Card | Shots at full fps | Shots in 30 seconds | ||||
---|---|---|---|---|---|---|
RAW+JPEG 56.6 MB | RAW 38.9 MB | JPEG 17.7 MB | RAW+JPEG 56.6 MB | RAW 38.9 MB | JPEG 17.7 MB | |
Lexar Professional 2000x UHS-II Rev E 64GB | 35 | 44 | 70 | 111 | 146 | 162 |
ProGrade 250MB/s UHS-II V90 64GB | 35 | 44 | 70 | 109 | 146 | 162 |
SanDisk Extreme Pro 300MB/s UHS-II 64GB | 35 | 41 | 70 | 109 | 146 | 161 |
ProGrade 200MB/s UHS-II V60 64GB | 28 | 29 | 70 | 69 | 91 | 162 |
SanDisk Extreme Pro 95MB/s U3 V30 64GB | 28 | 28 | 70 | 60 | 77 | 153 |
SanDisk Extreme 90MB/s U3 V30 64GB | 27 | 28 | 58 | 44 | 58 | 119 |
SanDisk Ultra 80MB/s 64GB | 28 | 25 | 58 | 35 | 35 | 77 |
Continuous shooting JPEG performance was worse than expected given the high RAW write speed of the EOS-R. The table above shows performance of various speed cards using different image modes. For this comparison the test scene produced 38.9 MB RAW files and 17.7 MB JPEG files (large, high quality). It should be noted that JPEG write speed was limited considerably by camera processing and the difference between memory cards was most apparent using cards with lower write speed.
The fastest cards in the Canon EOS R are Lexar 2000x UHS-II and ProGrade 250MB/s UHS-II V90 cards. These fast UHS-II cards provide the highest average write speed during extended continuous shooting. UHS-II cards provide a notable improvement over slower UHS-I cards but also cost significantly more. The Lexar and ProGrade cards averaged around 182 MB/s write speed during continuous shooting, providing 30 to 60 RAW shots at full frame rate, depending on the image subject. Additional high performing UHS-II cards include the Adata Premier One UHS-II V90, Sony SF-G UHS-II, Delkin Power UHS-II, SanDisk Extreme Pro 300MB/s UHS-II, Verbatim Pro II Plus V90 UHS-II and Integral UltimaProX2 UHS-II V90. All of the aforementioned cards are recommended for maximum continuous shooting performance with the EOS R.
UHS-I cards can provide decent performance in the EOS R for short bursts of photos, up to around 20 shots in RAW. After that the buffer may cause shooting to slow down and be limited by the write speed of the memory card. The EOS R also has an irregular shot interval when the buffer is full, capturing a few consecutive shots followed by a pause. The EOS R maintained up to around 75MB/s write speed using the faster UHS-I cards. Recommended UHS-I cards for the EOS R include various sizes and formats of the SanDisk Extreme Pro 95MB/s UHS-I cards.
The Canon EOS R has a USB Type-C port that can be used to transfer images from the camera to a computer. Canon states this USB-C port is equivalent to SuperSpeed USB (USB 3.1 Gen 1), which is technically equivalent to USB 3.0, and theoretically could provide up to 625 MB/s transfer speed. To test the transfer speed using the USB-C port on the EOS R, a Lexar 2000x UHS-II Rev E 64GB SDXC card was used in the camera. The card contained 200 RAW images totaling 10GB. Downloading the images using a USB 3.1 cable from the camera to a computer with SSD drive took 132 seconds and averaged 76.0 MB/s. Similar transfers using external UHS-II USB card readers averaged over 250MB/s. For maximum transfer speed a separate card reader should be used. Card reader tests are available in the Card Reader Reviews.