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With 1d x coming out ... soon, I'm curious on what would be the best memory to use with it, if price is no object.

Photo size of this camera should be somewhere in range of 20-30 mb, and with 12 frames per second that sums up to need to write down 300mb/s, or if we consider that the camera has dual card slot, this would amount to 150 mb/s per card (does this work this way?).

Is there anything on market that would sustain such a write speed?

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Canon 1D X Photo size of this camera should be somewhere in range of 20-30 mb, and with 12 frames per second that sums up to need to write down 300mb/s, or if we consider that the camera has dual card slot, this would amount to 150 mb/s per card (does this work this way?).

Is there anything on market that would sustain such a write speed?

Short: Almost

Longer:

The EOS 1D X has dual CF cards.

Maximum defined CF data transfer rate so far is covered by Revision 6 of the CF standard which was in November 2010 - this added UDMA mode 7 which is rated at 167 MB/s.

What the 1D X will and won't do is still something of a movable feast, but it seems likely that it will offer one or both of dual simultaneous write and interleaved file write options.
IF a CF card capable of maximum UDMA mode 7 was available and IF the camera is able to keep up with dual cards at full speed in interleaved mode, it could write 334 MB/s.
At 12 frames per second that would allow about 334 / 12 = 28+ MB / photo.

MY APSC Sony A77 with 24 megapixels writes 25 megabyte RAW files.

I recall seeing 100 MB/s CF cards announced within the last year. MAY have been LEXAR.
... Gargoyles ...
Yes. Lexar Professional1000X CF - 150 megabytes/second. Available in 16/32/64/128 GB capacities. Hidden in the fine print it says

  • Minimum 150MB/s read transfer, write speeds lower.

That is "naughty". I consider that a card,s write speed is it's fair rated speed - that's what the camera cares about when it matters. Looking elsewhere, apparently write speed is 145 MB/s - tolearable :-).

Wikipedia - Compact Flash

Compact Flash Association - surprisingly low in solid information

XQD:

The Nikon D4 offers dual memory - 1 x CF & 1 x XQD format cards.
Maximum XQD rate so far is 125 MB/s but the card is based on PCIe technology and PCIe 2X and 4X extensions support 250 and 500 MB/s transfers.

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  • \$\begingroup\$ The frame rate of a modern DSLR is less dependent upon the CF card speed and more dependent upon the speed of the in-camera buffer memory. The 1D X is actually capable of 14fps with mirror lockup, which at 30mb/photo would be a throughput rate of 420mb/s. The speed of the CF card is ultimately what determines your buffer-full time and post-full-buffer rate. A high speed CF card supports writing out images fast enough that the first shots are fully written out before you fill up the buffer. A slower CF card would limit the number of photos in a full buffer, and reduce post-full rate. \$\endgroup\$
    – jrista
    Jul 15, 2012 at 2:20
  • \$\begingroup\$ @Jrista - The question is explicitly & specifically about the ability of any memory card to keep up with the 1Dx, and if any would sustain the required write speed. Your buffer related comment and downvote are related to a question that was not asked. As an electronic designer I'm well enough aware of the interactions between data arrival rate, buffer size and data channel speed. To have discussed those aspects in this context would have complicated the answer and been irrelevant to what was actually asked. I have already addressed those points in other answers when relevant. \$\endgroup\$
    – Russell McMahon
    Jul 15, 2012 at 12:24
  • \$\begingroup\$ Your answer seems to indicate that the CF card affects frame rate, which it does not. It affects frame count before the maximum frame rate drops. I don't think the answer is invalid without an explanation of how frame rate and buffer depth are related to the CF card and card speed. It may complicate the answer, but its necessary information...it doesn't really matter how fast your CF card is...you'll still get 12fps or 14fps with mirror lockup regardless...however your post buffer-full rate will be more affected with slower cards. \$\endgroup\$
    – jrista
    Jul 15, 2012 at 16:11
  • \$\begingroup\$ @jrista - We each read my English differently. Odds are this is unfixable :-). HE stated target frame rate and target data rate and asked 3 questions (2 with question marks). (1) What is best memory with price no object? (2) Does it work this way? [ie do dual slots halve per card data rate](= maybe)(3) Is there anything on the market that would sustain such a write speed? || I seem and seemed to have answered his actual question. | Relevantly: SUSTAINED mean frame rate, which he asked about, IS set by card write speed if lower than camera max data generation rate (as we both agree). \$\endgroup\$
    – Russell McMahon
    Jul 15, 2012 at 22:44
  • \$\begingroup\$ The 1D X's write modes are either backup mode (write the same shot to both cards) or failover mode (write to the first card until full, then write to the second card). Interleaved writes, which I assume you mean to be writing two separate images to two cards simultaneously, is not an option (it wouldn't really make sense from a practical standpoint.) The maximum sustained write speed is 167mb/s with UDMA7, so it stands to reason there is no direct connection between achieving 14fps @ 30mb/s (420mb/s rate) and the speed of the CF card. \$\endgroup\$
    – jrista
    Jul 16, 2012 at 5:14
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As with just about any camera, a buffer will be used to hold a number of shots which are written to the card. Once the buffer fills, the frame rate slows. Even with the fastest cards today, previous generation cameras can't offload their buffer fast enough to sustain a high FPS indefinitely. So, this isn't a new problem to the 1D X or D4, though the speed they would require to do it is higher than ever before.

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