Mike Jacks0n Offline Upload & Sell: Off
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p.1 #2 · p.1 #2 · Did Canon ever explain why they went from 1Dx2's CFast to 1Dx3's CFexpress card? | |
CFast just didn't have the bandwidth to move forward. Even some of the 4k 120p data needs would stress the peak speeds of CFast.
In Canon's 8k RAW recording they require somewhere in the neighborhood of 400 MB/s sustained and the CFast cards could barely offer peak theoretical speed in that range.
Then if you consider the photo only bandwidth, moving 25 mega pixel images around 30 FPS in Canon's base compression (not its high compression CRAW), it puts you over the peak theoretical speeds of CFast as well. Luckily this is mostly written to a high speed internal camera buffer first, so a CFast card could work here, but it would still require significantly more time to clear the buffer, and has no chance of extending the buffer as CF Express can.
Quite simply, CFast wasn't fast enough for the processing that was on the horizon. Additionally, the good news is, CF Express is still in a stage where there is still a reasonable amount of headroom to push the card speeds up even further. I believe CF Express 2.0 is capable of 4000 MB/s on an older PCI e bus (PCIe 3.0 vs PCIe 4.0 or soon to be 5.0). For reference, generally each of the PCIe generations offer a 2x speed improvement. So there is tons of headroom if the market continues to develop along PCIe and CF Express. BTW, that last thing isn't guaranteed, XQD was also on a PCIe bus but when CF Express showed the higher promise, XQD was dropped like a bad habit.
As far as why they didn't offer the CFast cards in cameras like the 7D2 or 5D4, I'd assume it was based on the cost of the format. CFast cards were very expensive when the 1DX II was brought out, I can't imagine the cost a generation earlier. Also, those cameras would only have benefited from the extra speed in the buffer clearing, so I'd assume that would have been a tough sell.
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