5D Mark III and SD Card Speeds

[Sirpopealot]

Is there any truth to the claims in this link that the SD Card speeds are limited by the 5D Mark III to 133x?

Canon 5D Mark III and SD Cards

Thanks!

[ebiggs1]

I don't know but I use name brand cards.

Just don't want any problems! So far, so good!

[Richard]

Hi Sirpopealot,

We are unable to comment on information posted on third party websites. The information I am able to provide is based on information available on the Canon USA website at http://usa.canon.com.

That said, the memory cards in the SD slots do not slow down the camera unless the card is unable to accept input from the camera quickly enough.  In such cases, the buffer would become full which would result in an overflow error.

I hope this is helpful,

Richard

[zim]

No Richard, sorry not really helpful. It’s a simple question – Does the camera (5D3) default to the slowest card inserted which would be 133x?

If your going to answer questions by supplying links then there is no point to this forum.

[p4pictures]

EOS Mark III has a UDMA 7 capable CF slot and writes to those kinds of cards very quickly. If you put a UHS-1 type SD card in the camera then it's not so fast at writing since the camera doesn't provide the faster UHS-1 support. 

Also in my real world experience if you have an SD card and CF card in the camera then the SD card speed or camera controller speed becomes the limiting factor when writing the same content to both cards simultaneously. Regardless of the model or brand of SD card I have used in my 5D3 I cannot get the same write speeds as I get with a good fast CF card like the Sandik Extreme Pro cards.

Brian / p4pictures

[John]

With just a 400x CF card, my buffer size is 16 photos (full sized raw).  When I write to the CF and a 400x Lexar Pro SD card, the buffer drops to 13.  I'd go get a 600x SD card but the Internet tells me that will not change the drop in buffer size.

13 is sufficient but I never understood why camera manufacturers don't increase their memory buffer.  I suspect it is not a technical limitation but a product differentiation reason.

[dbltapp]

Why not just publish the write speeds for each type of card? That Canon doesn't do that suggests it's hiding something.

[Peter]

5DIII

Compact flash: 100MB/s.

SD: 20MB/s.

Together you can reach 120 MB/s for raw video. That is nice.

[dbltapp]

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@Peter wrote:

5DIII

Compact flash: 100MB/s.

SD: 20MB/s.

Together you can reach 120 MB/s for raw video. That is nice.

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I'm curious as to where you found those figures, as I've been (unsuccessfully) trying to find those specs for years.

[Peter]

You can try yourself with Magic Lantern and the benchmark function.