The Canon 5D Mark III has dual memory card slots that hold one CF (CompactFlash) format memory card and one SD (Secure Digital) format memory card. CF cards are faster than SD cards and perform better for video, making a CF card the most logical choice for your primary memory card. The dual slots on the Canon 5D Mark III also allow you to use the two cards simultaneously for a number of functions, including recording JPEG and RAW images on separate cards and recording the same data on both cards for backup.

 

Compact Flash (CF) Memory Cards

SanDisk Extreme Pro CF memory cardSanDisk Extreme Pro ($85 for 32 GB)

Min. Write Speed: 65 MB/s (Class 65)
Max. Write Speed: 150 MB/s
Max. Read Speed: 160 MB/s

Both SanDisk and Lexar make professional Compact Flash memory cards, and both companies upped the ante in 2014 with faster and cheaper models. The SanDisk Extreme Pro is a superb CF card: it has a write speed of up to 150 MB per second and an impressive sustained read speed of 65 MB per second. It also offers the Video Performance Guarantee (VPG-65) for recording at high frame rates including Full HD and 4K. And the Extreme Pro can handle the elements well and is rated for extreme temperatures from -13 to 185 degrees Fahrenheit. Considering that this card currently is slightly cheaper than the Lexar Professional below, we give it the nod (the latter only has 5 MB per second more maximum write speed and that’s it). 
See the SanDisk Extreme Pro

 

Lexar Professional CF memory cardLexar Professional ($87 for 32 GB)

Min. Write Speed: 65 MB/s (Class 65)
Max. Write Speed: 155 MB/s
Max. Read Speed: 160 MB/s

Lexar makes top-shelf CF format memory cards and the Lexar Professional 1066x has some the fastest write and read speeds on the market. This card replaced the older 1000x Lexar cards, boosting the minimum write speed from Class 20 all the way up to Class 65 (and the new version is cheaper). You also get the Video Performance Guarantee (known as VPG-65) for professional-quality recording at the highest resolutions. All things considered, there is a lot to like about this memory card, and it’s really a toss up between it and the SanDisk Pro. Given the nearly identical specs, we recommend getting whichever model is cheaper at the time of purchase.
See the Lexar Pro

 

SanDisk Extreme CF memory cardSanDisk Extreme ($55 for 32GB)

Min. Write Speed: 20 MB/s (Class 20)
Max. Write Speed: 60 MB/s
Max. Read Speed: 120 MB/s

If you’re not shooting extremely fast bursts or tons of video, the SanDisk Extreme is a viable option for a Compact Flash memory card. This card has similar technical specs as the previous generation of “professional” CF memory cards, including a very respectable Class 20 rating for video, which will perform well in most scenarios. Like the Extreme Pro, this card is rated for temperatures from -13 to 185 degrees Fahrenheit, and stands up to shock and vibration well. If you’re not a sports or action photographer and don’t usually shoot ultra-high resolution video, the SanDisk Extreme is a great way to save on Compact Flash.
See the SanDisk Extreme

 

Secure Digital (SD) Memory Cards

SanDisk Extreme Pro SD memory cardSanDisk Extreme Pro ($45 for 32GB)

Min. Write Speed: 10 MB/s (Class 10)
Max. Write Speed: 90 MB/s
Max. Read Speed: 95 MB/s

SD memory cards are inherently slower than their CF siblings, but are a nice option for still photos and as a backup. If you frequently shoot HD video, high-speed bursts, or transfer large volumes of files, the best professional SD memory card for the Canon 5D Mark II is the SanDisk Extreme Pro. With the fastest write speeds of up to 90 MB per second, it’s the leading SD memory card on the market today. Like the regular Extreme series below, the Extreme Pro features a durable design that is waterproof, shockproof, X-ray proof, and rated for extreme temperatures. It’s also U3 rated for high-resolution video. 
See the SanDisk Extreme Pro

 

Lexar Professional SD memory cardLexar Professional ($22 for 32GB)

Min. Write Speed: 10 MB/s (Class 10)
Max. Write Speed: 45 MB/s
Max. Read Speed: 90 MB/s

For still photography, the Lexar Professional gets the jobs done for about half the price of the SanDisk Extreme Pro above. If you’re shooting high-resolution video or fast bursts for sports or action photography, you likely will want the faster write speed of the Extreme Pro. But for the majority of still photographers, the Lexar Professional is fast enough on the Canon 5D Mark II to handle large photos relatively quickly. More, the maximum read speeds are nearly the same (a difference of only 5 MB/s), so you’ll be able to get photos off the card expeditiously. 
See the Lexar Pro

 

SanDisk Extreme SD memory cardSanDisk Extreme ($26 for 32GB)

Min. Write Speed: 10 MB/s (Class 10)
Max. Write Speed: 40 MB/s
Max. Read Speed: 60 MB/s

The most notable difference between the SanDisk Extreme and Lexar Professional above is that the former offers Class 3 U3 recording speeds for 4K video. The Canon 5D Mark III shoots Full HD video but not 4K (for that, try the Canon EOS 1D), so it’s debatable whether the extra few bucks are worth it (keep in mind that the SanDisk Extreme also has a slower maximum write speed by 30 MB/s). U3 ratings aside, the SanDisk Extreme offers write speeds of up to 40 MB per second and read speeds of up to 60 MB per second, and it can operate in extreme temperatures from -13 to 185 degrees Fahrenheit. If you’re video shooter using an SD card as a backup, we recommend the SanDisk Extreme.
See the SanDisk Extreme



Lenses for the Canon 5D Mark III

If you are still looking for the right glass, see our guide to the best lenses for the Canon 5D Mark III for great options from wide-angle to telephoto zoom. 

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