Comment And Question On the New Dual Card Slots In The Fuji X-Pro 2

Dual Cascades (click to enlarge)
Fuji X-T1, 18-55mm lens @ 18mm; 1.5 sec. @ f/11; ISO 200

One of the new features Fujifilm included in their new X-Pro 2 camera body is dual SD card slots.  I have had this feature in my last two Nikon digital SLRs and am a fan of it. This feature allows the photographer to use one slot or the other, write simultaneous duplicate files to each card, giving us an automatic backup file, write sequentially (overflow) from card 1 to card 2 so you double the number of images you can take before changing cards, have RAW files written to one and JPEGs to the other as well as some other options.

The Slot #1 in the X-Pro 2 is the one with the latest technology, taking the fastest SDXC cards available, such as the Toshiba Excercia Pro, the Lexar Professional 2000X and the Sandisk 280mbs cards which are all UHS II/U3 cards.  The second slot is a more traditional slot which will not allow the benefit of the fastest available cards (UHS I).

In my Nikon D800E and now my D810, Nikon has also given us dual card slots with largely the same options.  The main difference being in the Nikon one slot takes a CF card and the other a SDXC card.  Neither of these, however, can take advantage of the fastest cards mentioned in the previous paragraph.  So, I have some familiarity with this feature and, in fact, use it whenever I use my Nikon gear.

The problem with the Nikon, and I have not heard anyone address it with the X-Pro 2, is that if you, for example, are writing simultaneous files to both cards in the "automatic backup" mode, the camera's read/write speed is only as fast as the slower of the two cards.  In my D810, if I have a 1000X CF card in one slot and a 333X SDXC card in the second slot, effectively my camera's read/write speeds will only be as fast as that 333X slower card.  The buffer clears at the rate of the slower card.  I found that out early on and replaced all of my cards, both CF and SDXC, with the fastest cards available at the time.  In both slots, the same read/write speed cards are used.

This would apply writing dual files as well as RAW files on one card and JPEG on the other.  The speed of the cards in the Nikon govern overall speed.  I wonder about this in regards to the X-Pro 2.  Does the speed of the second slot in the X-Pro 2 artificially slow down the advanced speed of the card in slot 1 if you have a card in the second slot and are using any mode other than "overflow?"

As I said, I have not heard nor read anyone comment on this but it needs to be explored and examined so all owners can be aware.  

It would be a nasty surprise if an X-Pro 2 user bought some very expensive really fast cards but that extra money spent to gain the extra read/write speed was for naught since the second slot didn't allow the faster times before clearing the buffer.

One remedy some Nikon users took was to not use a secondary card at all, therefore not worrying about slowing down the camera under circumstances which demanded the absolute fastest read/write speeds.

If this issue has been addressed, I've missed it.  Please let me know if you have heard or read anything about it.  I suspect when Fuji introduces the X-T2, the same card arrangement will be included so it may affect future users as well.

Thanks for looking. Enjoy! 

Dennis A. Mook 

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