Camera Memory Speed has completed their comparison of which memory cards have the fastest write speed with the EOS 5DS. Needless to say, 50mp RAW files are enormous in size and having the fastest card you can inside the camera is important. Also not surprising, is SD cards (*note: Canon doesn't support UHS-II. thanks m8547) cannot come close to the write speed of a CompactFlash card, as the fastest card was the Lexar Professional 2000x UHS-II 32GB at only 71.8 MB/s.
How they test:
The 5Ds is mounted on a tripod and a remote timer is used for 30 second shooting intervals. A manual lens is used and focused using live view at maximum magnification. The subject is a static test scene under controlled lighting.
A comparison of different test subjects was conducted with the the Canon 5Ds. Using the Lexar Professional 1066x 128GB CF card, the most detailed scene resulted in 101.4 MB/s average write speed (75.6 MB average RAW file size), while a scene with moderate amount of detailed averaged 84.0 MB/s (55.7 MB file size), and with lens cap on 84.0MB/s (45.8 MB file size). The most detailed scene is used for this card comparison test. Read the rest of the article
Below are the 10 fastest cards from their tests.
- Lexar Professional 1066x 32GB CF 101.6 MB/s
- Komputerbay 1066x 128GB CF 101.6 MB/s
- Lexar Professional 1066x 64GB CF 101.5 MB/s
- Lexar Professional 1066x 128GB CF 101.4 MB/s
- PixelFlash SuperSport 1000X-PRO 128GB CF 101.3 MB/s
- SanDisk Extreme Pro 160MB/s 64GB CF 99.9 MB/s
- SanDisk Extreme Pro 160MB/s 32GB CF 99.8 MB/s
- Toshiba Exceria Pro 1066x 32GB CF 99.6 MB/s
- Transcend 1000x 128GB CF 99.5 MB/s
- Toshiba Exceria Pro 1066x 64GB CF 99.5MB/s
I found it interesting that a SanDisk card didn't make the top 5. However, we can't comment on how reliable the cards in this test are going to be. Although, we've only ever had a handful of memory cards fail and found Lexar and SanDisk to perform the same in that regard.