The need for speed

I offered to shoot the local park run a couple of weekends back and the core take away from doing that was the speed of writing the the photos to the card.  When the race starts you need to snap away at ten to the dozen.  Obviously it's a good idea not to shoot in RAW (which i'd forgotten to turn off).  The best quality JPG will be fine.  That aside it got me thinking.  How to best get the best throughput on the camera?

I shoot with a Canon 5D III.  So, what's the throughput on that?

There are two slots available; SD Card and CompactFlash.  If both are full then it writes to the slowest card first.  Go figure.  I'm sure there's a reason but eludes me.

The SD slot will never write faster than 133x.  The CompactFlash (CF) slot can use the UDMA7 protocol, whereas the SD slot cannot use the equivalent (UHS – for Ultra High Speed).

Okay, so if i'm shooting fast then leave the SD slot alone.

First - let's try this out in real life.

• Empty 8Gb SDHC card in
• Format the card
• Change the image type to Highest Quality JPG
• Put camera on High Speed Continuous
• Put the lens on manual so it's not focussing
• Hold done the button and see how many shots it takes

My old SDHC card managed 16 images in fifteen seconds.  Obviously this doesn't equate to 4*16 images in a minute as it was still emptying the buffer after the fifteen second had ended.

My 30mb/s card managed 20 images in fifteen seconds.

I'll borrow a fast CF card and see how fast that is in comparison.