Using An SD Card In The Canon 5DMkIII Brings The Camera’s Speed To Its Knees

Edit SD in 5DMarkIII 25pct no sd

Relax -- don't do it. Photo illustration Jeff Cable

Got a super-fast Canon 5D MkIII? Love that you can just pop out the SD card and slide it straight into your Retina iPad via the camera connection kit? Not so fast – literally. Photographer Jeff Cable has done the math and found that the camera’s SD slot is slow, slow slow compared the the CF slot, and then it actually gets worse.

Well…after some testing I have determined that, if you care at all about high speed shooting or clearing you buffer quickly, YOU DO NOT want to put a card in the SD slot.

Why? Because, for some reason unbeknownst to me, Canon decided to build the 5D Mark III with one very fast CF slot which supports the newer UDMA7 protocol and a standard SD card slot which does NOT support the high speed standard.

This, says Jeff, means that the maximum in-camera write speed for even a 600x SD card is 133x. Worse, the camera defaults to the maximum speed of the slowest card you put in there. Thus, you can put in a 1000x CF card and you’ll be fine, but if you put any SD card into the other slot, the whole lot is slowed down to 133x.

Ouch.

This reminds me of wireless networks, which are slowed to accommodate the worst device on the network. Modern routers like Apple’s AirPort Extreme and Time Capsule get around this by using two radios working at different frequencies. It’s hard to see why Canon didn’t come up with a similar solution, although I have a feeling it might have something to do with the DIGIC processors having some trouble with the mixed bandwidths (although this is just speculation). Either way, it looks like using the second, slower card slot in any camera is a bad idea.

(And finally, a terrible pun: If Jeff shot portraits and asked the models to sign a model release form, would it be called a Jeff Cable Release?)

Related
  • Tallest_Skil

    This is CultOfMac, not CultOfRandomTechNonsense.

    Passing references to Apple do not a valid article make.

  • joewaylo

    This is CultOfMac, not CultOfRandomTechNonsense.

    Passing references to Apple do not a valid article make.

    Actually it is in reference to Mac. If you read it again, the owner of the “Canon MDMkIII” pulled out his SD Card and placed it in the “iPad” card reader which downloads your photos into the iPad. Then swapped it back and it made his camera very slow.

    The iPad is developed by Apple. Hence a COM article relation.

  • Tallest_Skil

    Actually it is in reference to Mac. If you read it again, the owner of the “Canon MDMkIII” pulled out his SD Card and placed it in the “iPad” card reader which downloads your photos into the iPad. Then swapped it back and it made his camera very slow.
    The iPad is developed by Apple. Hence a COM article relation.

    Thanks for making the same point that I’m making. Passing. Reference. The article had nothing to do with it being a Mac. It’s the author complaining about a deficiency in the Canon hardware. This article has nothing at all to do with anything of Apple’s.

  • macmaniac

    Blame the SD Card, not the camera and please know some basic how a ultra fast camera processor works.

    I use 5D every weekend and no problem with my SD card, You know why ?
    You need a 60MB speed card which will cost you a lot.
    I remember paying close to 500 for my 60 MB card.

About the author

Charlie Sorrel Charlie Sorrel is the Reviews Editor here on Cult of Mac. Follow Charlie  on Twitter at @mistercharlie.

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