Write Speed of a 5D Mk III?

I am looking at stocking up on flash cards, and I am wondering where the bottleneck is on data write. Does anyone know how to find out the max write speed of a 5D Mk III? No point in buying a 510 MB/s rated card if the fastest the camera can write is less than that.

Rad

Here is a good site showing the write speeds of various cards.

http://www.robgalbrait​h.com …e7de5.html?cid=​6007-12452

Even thought the 5D3 may only max out at write speeds of about 60-80MB/s, you will see that those speeds are only attained with cards that are rated for much faster speeds. You really don't need all that speed as the 5D3 has a very good buffer and faster cards just clear the buffer more quickly. This would come into play when shooting RAW at 6fps.

I would just get a suitably sized Brand name card of at least 300x or 45MB/s

Sadly, the RG Card database is no longer what it was in the past, never updated, and all the historic data removed.

That said, one of the key points illustrated in this 2012 snapshot is that the 5D3 was doing 80MBs on the fastest CF fully 4 times faster than the SD cards of the time.

what we can;t see is that newer and MUCH faster SD cards are still slow in the 5D3 as compared to CF cards.

CyberDyneSystems wrote in post #17531129
what we can;t see is that newer and MUCH faster SD cards are still slow in the 5D3 as compared to CF cards.

I believe this is because 5D3 does not take advantage of UHS-1 even when standard was available at the time. Same as 7D2 does support UHS-1 but not U3. Canon for weird reason does not support latest card standard even in the 1D series when compared to Nikon. Although this is kinda moot point when looking at most recent cameras as they are "fast enough". But that also dued to the fact that we have not grown much in term of data throughput. pixel counts and color bits have not change much over the recent years.

OK, so for EXACTLY the same price ($59.95 usd) Amazon has the following Lexar UDMA 7 CF cards:

64G at 800x or 32G at 1066x

Using the chart above as a rough guide, it seem as though the burst will be measured in the dozens of frames regardless of which I choose. Is that correct?

So it's a matter of how many dozen shots I need in a burst? Right?

Rad

Also, if you want the best write speeds, use a fast CF card and NO SD card at all.

If you write RAW to both cards simultaneously then your write speed will be limited by the SD card, the upper limit of which is around 45MB/s I believe, due to the lack of UHS-1 compatibility.

You might think you could write RAW to the fast CF card and JPG to the slower SD but unfortunately this also seems to slow performance right down.

Basically if maximum sustained burst speed is important you need a good CF card and leave the SD slot empty.

Thanks for the heads up.

I ended up buying a couple of 64g 800x Lexar cards for 60 bucks each.

Kind of hard to believe that my first digial camera (a kodak point and shoot) used a 32 meg card. So this has 2000 x the capacity! Crazy.

Rad

I wish the 5D3 is UHS-1 compatible. I just brought the 7D2 which is U1 compatible and holy crap shooting RAW 10fps on that can still clear the buffer very fast. It is way more efficient than 5D3 in that regard even comparing Samsung U1 SDXC in 7D2 to Lexar 1066x card in 5D3. BTW it is kinda cheating cuz that Samsumg card is even faster than Lexar pro U3 and Sandisk Extreme U1 card.

Vertigo1 wrote in post #17533418
Also, if you want the best write speeds, use a fast CF card and NO SD card at all.

If you write RAW to both cards simultaneously then your write speed will be limited by the SD card, the upper limit of which is around 45MB/s I believe, due to the lack of UHS-1 compatibility.

You might think you could write RAW to the fast CF card and JPG to the slower SD but unfortunately this also seems to slow performance right down.

Basically if maximum sustained burst speed is important you need a good CF card and leave the SD slot empty.

Are you saying it's no faster to write JPG to the SD instead of RAW to the SD? (Assume in both that RAW to CF). I'm planning to get a 5dIII sooner or later but mainly for weddings and not so much sports or action.

I just bought that 64gb CF Lexar 1066x and planned to leave it in there the whole wedding and change out SD cards periodically.

Silver-Halide wrote in post #17535314
Are you saying it's no faster to write JPG to the SD instead of RAW to the SD? (Assume in both that RAW to CF). I'm planning to get a 5dIII sooner or later but mainly for weddings and not so much sports or action.

I just bought that 64gb CF Lexar 1066x and planned to leave it in there the whole wedding and change out SD cards periodically.

Not safer, but rather slower. Meaning if you put fast SD card in the slot, you can write RAW to both card, but if you have one card write RAW the other write JPG then it slow down even more. If you don't care about 2nd copy in the camera then you can use just the CF for best performance(fastest write speed). But if you care about having a 2nd copy in camera then that speed will have to sacrifice, but you still better off writing RAW to both cards. Unless you are one of those that need RAW for yourself and JPG for whomever right at the event, then you screw the performance to the worse case 5D could perform.

I generally shoot to the CF card with the SD card being used as backup only if the CF should fill up. Set up this way I see no slow down in write speed. However, on those occasions when I shoot to both the CF and SD simultaneously I do notice a down in write speed. Write speed is also slower if I shoot to the SD card only.

One thing that frustrates me about the 5DIII is if you remove the CF card and close the cover then reinsert the CF card the camera defaults to the SD card. The first time that happened to me I thought something was wrong with the camera because it slowed down noticeably. Anytime the SD card is used to record, the write speed will slow down compared to writing to the CF card only.

Thanks a bunch for your insight. I'm going to do RAW to both. Along with the better autofocus, the fuel card slots are the main reason I want to use the camera for weddings. Color me snoody but I like RAW over JPG.

Do you know if it is possible to put an SD card in, but not turn it on? Yesterday, I drove for an hour to get to my place, and found that the CF card was still in the reader connected to the computer at the hotel.

It would be nice to have that as a safety, for when the old (Jesus...Im only 56!) brain does this s*** again!

But would the mere presence of the SD slow down the CF, even if I am not writing to the SD?

(I would look it up, but I don't have the manual with me, so thanks to anyone who knows!)

Rad

you could always carry a spare card in your wallet...

Sparky98 wrote in post #17535779
I generally shoot to the CF card with the SD card being used as backup only if the CF should fill up. Set up this way I see no slow down in write speed. However, on those occasions when I shoot to both the CF and SD simultaneously I do notice a down in write speed. Write speed is also slower if I shoot to the SD card only.

One thing that frustrates me about the 5DIII is if you remove the CF card and close the cover then reinsert the CF card the camera defaults to the SD card. The first time that happened to me I thought something was wrong with the camera because it slowed down noticeably. Anytime the SD card is used to record, the write speed will slow down compared to writing to the CF card only.

I see this too, and even though I always try and remember to hit Q and set it back to the CF card, every now and then I forget.