Canon 5DM3 Dual Card Slots

[wideangle]

What's the maximum speed you can get from the SD Card slot when using one in a Canon 5DM3. From what I understand the 5DM3 isn't able to access the fast write speeds on new model SD cards so would be limited if shooting high burst rates as the card would buffer. So would it be a waste of money buying faster memory cards for the SD card slot, rather get a lower speed higher capacity card and save money as the speed isn't able to be fast speed of new SD cards isn't going to be accessed in camera anyway. The only benifit I could see is when it comes to downloading the images with a USB3 card reader onto a PC, then you could access fast speeds of the SD card?

[ameerat42]

Pretty well right, but...
Calculate how many burst mode shots to fill the buffer, and use that as a guide.

[wideangle]

Pretty well right, but...
Calculate how many burst mode shots to fill the buffer, and use that as a guide.

Thanks. I mainly shoot still images so don't belive its a worry with the limiting speed factor of the SD card. It's good to know though because it would be a waste of $$ getting a very fast card speed if the max speed it can be written to with the 5DM3 is around 20mb/sec! I take it the CF card slot accepts the latest speeds offered?

[ameerat42]

I use a 60MB/Sec CF card, mainly because of the fast download speed via the USB3 card reader. Its xfer is about 100MB/Sec.
Inside the camera I could get away with a 30.

[wideangle]

I use a 60MB/Sec CF card, mainly because of the fast download speed via the USB3 card reader. Its xfer is about 100MB/Sec.
Inside the camera I could get away with a 30.

Whats the fastest speed the 5DM3 can write at on a CF Card? Would it be able to write up to 160mb/sec cards?

[ameerat42]

AFAIK it can "use" these cards, but it may not match the max write speed of the card.
So the card will have time to twiddle it thumbs while being written to.

[I @ M]

This one pretty much tells the story ---- http://www.dpreview.com/reviews/cano...5d-mark-iii/13

[jev]

I just answer with a single URL: http://www.robgalbraith.com/camera_w...cid=6007-12452

[Warbler]

The SD slot in the 5D3 is woefully slow. What's worse is if you write to both cards simultaneously, the CF write speed slows to match the SD slot. It makes no difference to speed in mine if a use a Lexar 600X card or an old Sandisk 20mb/sec Extreme card. Hopefully the 5D4 will have dual CF slots like the 1DX.

[wideangle]

The SD slot in the 5D3 is woefully slow. What's worse is if you write to both cards simultaneously, the CF write speed slows to match the SD slot. It makes no difference to speed in mine if a use a Lexar 600X card or an old Sandisk 20mb/sec Extreme card. Hopefully the 5D4 will have dual CF slots like the 1DX.

So if you just use the SD card as a overflow card once the CF card is full, you still get the full speed of the CF right?

[Warbler]

Yes, when writing only to the CF card, speed is unaffected. Whenever you write to the SD card, things slow down markedly.

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In the table that Joost linked, I am using a Lexar 32gb 1000x Professional CF card and a Lexar 64gb 600x Professional SDHC card. I haven't timed it, but the figures in that table would be about right from what I've experienced, if I'm reading the right lines. The SD card is about 25% as fast as the CF card.

[wideangle]

Yes, when writing only to the CF card, speed is unaffected. Whenever you write to the SD card, things slow down markedly.

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In the table that Joost linked, I am using a Lexar 32gb 1000x Professional CF card and a Lexar 64gb 600x Professional SDHC card. I haven't timed it, but the figures in that table would be about right from what I've experienced, if I'm reading the right lines. The SD card is about 25% as fast as the CF card.

OK, thanks for that. I guess those shooting landscapes and architecture, aka still moving subjects and no need for large in camera buffer clearence then its not too bad.

[Warbler]

OK, thanks for that. I guess those shooting landscapes and architecture, aka still moving subjects and no need for large in camera buffer clearence then its not too bad.

No, it would be fine for that, but you'd still be wasting your money buying fast SD cards for the 5D3, no matter what you shoot.

[wideangle]

No, it would be fine for that, but you'd still be wasting your money buying fast SD cards for the 5D3, no matter what you shoot.

I guess a benift of a faster card would be the transfer speeds to a computer would be fast. Could be worth getting if say you have a 32GB card to take photos off.

[arthurking83]

I guess a benift of a faster card would be the transfer speeds to a computer would be fast. Could be worth getting if say you have a 32GB card to take photos off.

This is the only reason I got a reasonably fast card for my D800.
Writing to the card is pretty slow on the D800 too, but not slow as in the internal specs are simply slow .. the files are huge so it seems slow.
But once you have 32-ish Gig's of files .. even with a speedy USB3 reader and speedy card it's still feels slow when transferring everything .. again not because the hardware is slow .. it's just that on average the D800's files are 90-100Mb .. so it seems slow.

If I use the same cards in the D300, everything is transferred in a fraction of the time, D300 has 20-25ish Mb files, as opposed to 90-100Mb files.

Another benefit of getting a faster card, apart from quicker read rates, is that if at some point in the future you get a new camera with faster write speeds, you already have the card hardware for it to make use of that benefit.

I suppose it's a balance between how much you want to spend vs how quickly you want to get things going .. vs how much data you want to store .. etc, etc.

[Warbler]

Whilst I don't disagree with the argument about faster cards reading faster, if you don't already have a USB3 card reader, than your money would be better spent getting one of those. Also, if you buy a fast card in the expectation of putting it in your new camera that you may buy in future, you may find that when that time comes, you're putting a relatively slower card into it than is (then) available, cheaper. Still, that is a decision for you to make. The speed of cards is increasing, and the cost decreasing.

I'm still pi$$ed with Canon putting such a slow SD slot in the 5D3. I'm also annoyed that I didn't read anything telling what Canon had done before I spent my money. Surely it couldn't have been because of expense. Funny how Canon is fixated on competing in the video market with its DSLRs and most of us never use video. Might be a POLL there somewhere. Yet, Canon gives us video and skimps on wiFi, GPS, write speed etc.

[ameerat42]

That's right, Warbs. But you need to have USB3 ports on your computer as well. At 1st, I tried a PCIe to USB3 card. No change!!! Just lost a slot.
On the new Asus laptop with 3 x USB3 ports - lightning!

[wideangle]

Whilst I don't disagree with the argument about faster cards reading faster, if you don't already have a USB3 card reader, than your money would be better spent getting one of those. Also, if you buy a fast card in the expectation of putting it in your new camera that you may buy in future, you may find that when that time comes, you're putting a relatively slower card into it than is (then) available, cheaper. Still, that is a decision for you to make. The speed of cards is increasing, and the cost decreasing.

I'm still pi$$ed with Canon putting such a slow SD slot in the 5D3. I'm also annoyed that I didn't read anything telling what Canon had done before I spent my money. Surely it couldn't have been because of expense. Funny how Canon is fixated on competing in the video market with its DSLRs and most of us never use video. Might be a POLL there somewhere. Yet, Canon gives us video and skimps on wiFi, GPS, write speed etc.

Good point regarding memory card speeds increasing all of the time. Just a few years ago the top card speeds were around 45mb/sec. Now the same card can be brought with 150mb/sec speeds! It makes a big difference when transfering large files from USB to computer. On average a 32GB card on a card that reads at 45mb/sec would take about 16 minutes. The card that reads at around 150mb/sec would only take 4 minutes! If you only have USB 2 pins on your computer your bottlneck is USB2 speeds regardless of how fast the memory card is. You only get around 15-20mb/sec transfer speed via USB 2 transfer. That same 32GB card would take around 37 minutes to transfer to computer!

[Tommo224]

I read online that the 5D3 SD slot is 45mb/ps max. The CF is full high speed though! I can't reach buffer if I try. Unsure why they skimped on that, but my 550D had high speed?

I had 96mb/ps cards for my 550D, and was shocked when I used them on my newly purchased 5D3 to find that the photos were really slow and I was smashing the buffer.

I changed to CF cards, just a basic one off a friend and I wasn't reaching the buffer as quickly! So when I purchased new ones, I went with the Lexar 1000x Professional. 2 years later, one died (probably due to temperature elements when in Alaska). I'll purchase two more of the newer 1100x ones from Adorama soon! They are great cards though, but really unsure what happened to the one that died

[wideangle]

I take it that with the the 5DM3 dual card slots it doesn't matter if you have say a 32GB in the CF slot and a 8GB in the SD card slot? ie - they don't have to be identical?