if compact flash card (CF) is better than SD card, then why canon 60D replacer slot with SD card slo

Started Dec 3, 2012 | Questions thread
Doug Pardee
Doug Pardee Veteran Member • Posts: 8,905
CF (qua CF) has reached the end of the line

The CF specification, as defined by the CompactFlash Association, has reached its limit. The CF specification allows for up to 64GB of memory with a maximum access speed (with UDMA 6) of 900x (133 MBytes/sec). That's all that can be handled in a fully-compatible way.

The CompactFlash Association has essentially frozen the CF specification and moved on to CFast for industrial uses and XQD for consumer usage. Those cards and slots aren't compatible in any way with CF (or each other). To my knowledge, no digital camera uses CFast and the only one that takes XQD is the Nikon D4.

Lexar, in conjunction with Canon and Nikon, has created its own extension of the CF specification with larger capacities and higher speeds (using UDMA 7). This is a one-way compatible technology: a camera built for Lexar-extended CF can use regular CF cards, but a camera built for regular CF cards can't use Lexar-extended CF. The Nikon D4 supports Lexar's CF in addition to XQD. Canon seems to have thrown its lot in with Lexar, ignoring XQD but supporting Lexar's CF in the 1D-X and 5DmkIII, and — with firmware updates — the 1DmkIV, 5DmkII, 7D, and 50D. To my knowledge, Lexar is the only manufacturer of these extended CF cards.

The SD technology, in contrast, has much more room to grow: SDXC allows up to 2048GB and, with UHS-II (which isn't yet available), speeds up to 2000x.

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