Camera Memory Speed
Memory Card Comparison & Performance Tests for Digital Cameras
Canon 5D Mark IV with SD / CF memory cards and door open

Canon 5D Mark IV SD & CF Card Write Speed Comparison

The Canon EOS 5D Mark IV is the latest update in the venerable 5D series. A new 30.4MP full-frame sensor and Digic 6+ processor are combined with the advanced autofocus features from the 1D X Mark II. Its video capabilities are expanded to include 4K recording at 24 and 30p. The Mark IV provides up to 7fps continuous shooting. The camera features one CompactFlash and one Secure Digital card slot and supports UDMA7 in the CF slot and and SD/SDHC/SDXC cards and supports UHS-I.

The Canon 5D Mark IV camera was tested with 112 memory cards: 87 SD cards and 25 CF cards. The cards are evaluated for write speed for continuous shooting of RAW images as well as the number of shots taken in 30 seconds of continuous shooting for RAW+JPEG, RAW and JPEG image modes. An analysis provides additional information observed in the tests. The fastest SD and CF cards for the 5D Mark IV are drawn from the test results.

Camera Details and Settings

The 5D Mark IV test uses a manual lens and manual settings. The camera is mounted on a tripod and activated using a remote timer. The subject is a detailed test scene illuminated with controlled lighting.

Write speed is calculated using the buffer full condition during extended continuous shooting; the total amount of data written to the card divided by the write time. This calculation provides a more accurate result than the card access light because the the light turns on when the shutter is first activated rather than when the image has been processed and begins writing to the card. Write speed is in megabytes per second MB/s (1 MB = 1,048,576 bytes).

Canon 5D Mark IV Write Speed Comparison

Canon 5D Mark IV Continuous Shooting

The following table shows the number of shots taken in 30 seconds of continuous shooting using the 5D Mark IV. The time does not include the buffer clearing or write time. The test is repeated for three image modes: RAW+JPEG, RAW, and JPEG. The JPEG setting is large, high quality. The camera is set to continuous high release drive mode. Average RAW file size is 38.5 MB. Average JPEG file size is 14.0 MB.


The Canon 5D Mark IV provides UHS-I support including SDR104 for high write speed. The CF card slot supports up to UDMA 7. The camera does not does not support UHS-II, but UHS-II cards can be used in the camera because the cards revert to UHS-I mode. UHS-II cards offer no speed benefit in the camera compared with fast UHS-I cards, but do provide the ability to download images faster when used in a UHS-II card reader.

The fastest card type for the 5D Mark IV is CompactFlash. In this camera, CF cards perform faster than SD cards when shooting RAW. In RAW, the fastest CF cards averaged up to 112 MB/s, while SD cards provided up to about 81MB/s average speed during continuous shooting. These are not a peak write speeds, but the average during extended shooting, including internal delays and processing in the camera.

When buffer capacity is provided in number of shots, its meaning is often misunderstood. It is not a static number because it changes with camera settings, cards write speed (the buffer may be clearing while the camera is still shooting) and image subject. Comparing buffer capacity using the detailed scene in these tests, all cards provided essentially the same number of RAW+JPEG at high frame rate before slowing. Using the most strict method this would be 11 shots, however the delay between shots 12, 13 and 14 only included a few extra hundredths of a second delay, so it might be considered to be 14 shots. The number of shots in RAW mode varied with different speed cards, from 15-18 shots, with faster cards providing more shots because they allow more images to be cleared from the buffer. Again, the last few shots may have had a few extra hundredths of a second separating. In JPEG mode the buffer capacity ranged from 19-31 shots. The number of shots, especially when shooting JPEG, can vary significantly with different image subjects and camera settings. A less detailed subject and/or lower quality JPEG setting can result in more shots. Indeed, shooting at 1/8,000 shutter speed with the lens cap can provide essentially unlimited JPEG shots at full frame rate when using a fast card.

Buffer capacity might also be considered in terms of total size in bytes. For RAW images in these tests, it would be estimated around 1GB using the amount of data cleared after the last shot of a buffer-full continuous shooting burst. This is not actually the internal memory of the camera, which would be larger to accommodate data as it comes off the sensor before it has been processed. This is apparent when looking at JPEG buffer capacity, which indicates a much smaller buffer, or RAW+JPEG which indicates a larger buffer. However, it may be useful to consider this capacity when comparing buffer capacity to other cameras.

In terms of memory card performance, perhaps the most interesting number to consider is the frame rate that can be sustained with the buffer full. This rate depends on card write speed, in fact itcan be calculated by dividing the average write speed by the file size. The rate in fps varies with image subject because the amount of detail affects file size. Using the detailed test scene in these tests, shooting RAW+JPG with the buffer full, the fastest cards provide up to 1fps while slow cards straggled to maintain 0.1 fps (101.5 MB of data for each shot writing at 10 MB/s), meaning up to 10 second average shot interval when the buffer is full! Shooting RAW, the rate varied from 1.3 fps for fast cards down to 0.15 fps for the slowest. In JPEG mode the rate ranged from 3 fps for fast cards down to 0.4 fps for slow cards. The shot interval with the buffer full was not constant, two shots would often be taken in fast succession followed by a delay.

One might question whether using two cards would allow more shots during continuous shooting. To test this, the Lexar Professional 1066X 128GB and Lexar 2000x UHS-II 32GB cards were used in the same test setup as in the 30 second continuous shooting test. Shooting RAW+JPEG with the RAW going to the CF card and JPEG to the SD card, the result was the same number of shots as shooting with all images writing to the CF card: 41. Switching to RAW on the SD card and JPEG on the CF, the result was 36 shots. This was more shots than the SD card alone could take, but still less than using the other configuration or the CF card alone. Writing both RAW and JPEG to both cards resulted in 32 shots, the same as when shooting both to the SD card only. Shooting RAW only and writing to both cards resuled in 40 shots, also limited to the same number as the SD card alone would provide. Shooting JPEG to both resulted in 101 shots, practically the same as shooting to only one card. Backup modes appear to have no speed penalty compared to only writing to the SD card, but writing RAW+JPEG to different cards provided no speed benefit.

Fastest CF Cards for the Canon 5Ds

Fastest CF card:
101.6 MB/s write (RAW)
Lexar Professional 1066x CF Card
Lexar Professional 1066x 32GB CF Card
Fastest CF card:
101.6 MB/s write (RAW)
Komputerbay 1066X 128GB CF Card
Komputerbay 1066x 128GB CF Card

The fastest cards for the Canon 5Ds are CompactFlash cards. CF cards allow the highest write speed during continuous shooting (RAW and RAW+JPEG). The Lexar Professional 1066x 32GB CF Card provided the highest write speed of 101.6MB/s average when shooting RAW and edged out the other cards in number of shots in 30 seconds RAW+JPEG shooting (42 vs 41 or lower). The difference between this card and the competition was slight, but repeated in multiple tests. Also performing at 101.6 average speed was the Komputerbay 1066x 128GB CF card. Komputerbay is a lesser-known brand but offers a good value in fast, large capacity fast CF cards. The fastest CF cards from most brands provide the essentially same level of performance in the 5Ds, the small differences seen here could be attributed to sample variation; the write speed appears to be limited to around 100MB/s (average) by the camera rather than the maximum write speed of the card.

Fastest SD Cards for the Canon 5Ds

Fastest UHS-II card:
71.8 MB/s write (RAW)
Lexar Professional 2000x UHS-II SD Card
Lexar Professional 2000x UHS-II SD Card
Fastest UHS-I card:
71.7 MB/s write (RAW)
SanDisk Extreme Pro 95MB/s UHS-I SD Card
SanDisk Extreme Pro 95MB/s UHS-I SD Card

The fastest SD cards for the Canon 5Ds are the Lexar Professional 2000x UHS-II and SanDisk Extreme Pro 95MB/s UHS-I cards. The Lexar is a UHS-II card, but operates at UHS-I speed in the 5Ds. It does have an advantage if download speed is important. In a UHS-II card reader, this card can sustain transfer speeds above 250MB/s. However, the 5Ds the card operates at UHS-I speed, making the UHS-II card subject to the same limit as the SanDisk Extreme Pro UHS-I card. (The SanDisk Extreme Pro UHS-II card did not perform as well because it does not support SDR104 UHS-I bus mode.) In terms of price, the SanDisk Extreme Pro 95MB/s UHS-I card is the better value.

In general, SD cards are a good value choice. They are less expensive for a given capacity compared with CF cards. Only the fastest and most expensive CF cards provided the write speed advantage. Many devices have built-in SD card readers, making SD cards more convenient. Some may eschew SD cards for their small size or durability concerns. However in the 5Ds, continuous shooting performance for JPEG was essentially equal between the fastest CF and SD cards. Some SD cards to consider include the Samsung PRO SD cards, Lexar Professional 633x cards and for large capacity, the SanDisk Extreme 80MB/s 128GB and 256GB cards.

Canon 5D Mark IV with USB 3.0 cable port door open

Transferring images from the Canon 5D Mark IV

The 5Ds has a USB 3.0 port that can be used to download images to a computer. Using fast CF and SD cards in the camera, the average speed was calculated transferring 5GB of images from the camera to a SSD drive on a computer. Using the Lexar 1066x 64 GB CF card, the transfer averaged 53.4 MB/s, while the SanDisk Extreme Pro 95MB/s 64GB UHS-I card averaged 65.4 MB/s. These speeds are well above USB 2.0, but far below what is possible using a separate USB 3.0 card reader. Download speeds up to 90 MB/s are possible for UHS-I cards, and 250 MB/s for UHS-II cards. CompactFlash cards can provide up to 140MB/s copying actual RAW files using a USB 3.0 card reader. Additional card reader speed tests are available in the Card Reader Reviews.