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Old May 23, 2015, 9:35 PM   #1
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Default card rdr won't read sd card

I have a Lexar CF/SD card reader. It works on the compact flash just fine. I've used it for several years. I recently got a camera with dual card slots, CF and SD.
The CF card is read by the card reader as normal, but when I put the SD card in, I get a message to the effect of "the card must be formatted before you can use it"

Its a full 64 G card, there are more than 3,000 raw shots on it. I'm using a built in card reader on another PC to download them at the moment.

I have tried 2 different 64 G SD cards and get the same message with the card reader, but there *are* photos on the SD card.
Canon 7D Mark II
Sigma 18-200, and Canon 70-200 f 2.8L , plus a bunch of other stuff
Kalispell, MT
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Old May 24, 2015, 6:19 AM   #2
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Does your card reader support SDHC format or just the older SD format which topped out at 2GB?
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Old May 26, 2015, 2:48 PM   #3
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64GB, huh?

Cards in the Secure Digital form factor come 3 different ways. SD (for cards 1MB to 2GB in size), SDHC (for cards 4GB to 32GB in size), and SDXC for cards that are 64GB to 2TB in size.

See more about the differences here:


Your 64GB card falls into the SDXC category. Those cards are formatted using the exFAT file system from their manufacturers, which has some benefits over FAT32 (as used by 32GB and smaller SDHC cards). More about exFAT here:


But, your card reader and Operating System (OS X, Windows XP, Vista, etc. will both need to be designed to work with SDXC Cards and the exFAT file system.

What Operating System are you using? If you look at the adoption section on this wikipedia page about the exFAT file system, it contains footnotes with things like updates and service oacks needed for older versions of Windows in order to read files from exFAT. With Windows 7 or 8.x, support is already built in. With OS X, you'll need to be using 10.65 or later for exFAT support.


With Linux, a FUSE driver is available for exFAT support. But, there is also a native exFAT driver that some Linux distros are starting to include with their kernels.

But, again, your card reader will also need to support SDXC Cards. If you're using a reader that's a few years old, it may not work with them.
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Old Jul 29, 2015, 4:03 PM   #4
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...or buy for $ 5 an USB3 cardreader for SD/microSD ...

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