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How fast of a CF card do I need to buy for my 7D?


Anna Clara Casapollo

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I've used the Lexar Professional 300x cards in a 5D, which were fine, but really the data rates involved aren't that huge - a 40 megabit h.264 stream (assuming the 7D is similar to the 5D) is only barely 8 megs a second, and 300x on a CF card equates to about 40.

 

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In the interest of full disclosure, I'm a PR rep for Lexar. Congratulations on purchasing a 7D. The 7D is UDMA-6 CompactFlash compatible, meaning it can take advantage of UDMA memory cards, which provide faster transfer speeds, both in the camera and when moving images to your host computer for editing (if used with a UDMA-compatible card reader).

 

Lexar offers a number of UDMA CF cards you could consider, including the Lexar Professional 600x CF (available in 8GB. 16GB and 32GB capacities), the Lexar Professional 300x CF card (4GB, 8GB and 16GB capacities), and the Lexar Professional 233x CF (available in 8GB).

 

You should also consider a UDMA-compatible card reader. Both the Lexar Professional FireWire 800 CF reader and the Lexar Professional USB Dual-Slot reader are UDMA compatible.

 

Good luck on your purchase!

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Not to derail the thread, but while we have a Lexar guy here.

 

I did a two-day shoot on a 5D with Lexar "Professional UDMA" 300x 4GB CF cards. We had quite a high incidence of both single-bit and clustered errors in files we offloaded on a USB card reader. Now, we have to be clear that this is probably not a fault in the cards, as we eventually ended up downloading all this stuff twice and the glitches were different each time, but even doing that we did end up with a few shots that had to be spliced together out of various un-corrupted bits of several files.

 

I guess your solution is probably just to buy one of the really high end Lexar-branded card readers, but do you do any sort of testing on this? You probably should; it'd be a selling point for all the CF cameras that are currently out there.

 

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I use the Lexar 8GB 300x UDMA cards which work great. It's a bonus that they work with the Red camera too. I don't see any reason to get the faster ones, though larger capacity would be a good thing. The 8GB cards don't hold that much footage. I've also worked with the 32GB 233x Sandisk cards, which were ok on the 7D too.

 

I use the Lexar FW800 UDMA CF reader, as well as a Sandisk FW800 UDMA CF reader, both of which work fine (and I don't work for Lexar, FWIW :)).

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Yeah, I'm assuming it was probably the nasty little USB card reader we had. We were using an Eee-PC as an intermediary between the CF reader and a couple of USB hard disks. Fantastically portable low-power solution but I'd certainly have invested in a FW card reader if it had been more than a couple of days' tests.

 

If it were me, though, I'd still copy everything off the card twice and CRC it. What sort of precautions do you do?

 

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If it were me, though, I'd still copy everything off the card twice and CRC it. What sort of precautions do you do?

So far, just drag and drop, then visually verify each clip. I guess I should do checksums to be safe, hope someone writes a program like R3D Data Manager for 5D/7D soon.

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I think the 30Mbs (200x) are the minimum that you want to get, but I have read a couple of people who compared cards and thought that 30Mb/s did seem to be pushing it slightly. The 45Mbs (300x) is probably the minimum I would get if I were buying a new card. I have heard that the 90Mb/s (600x) is not noticeable enough to justify the cost vs the 60Mb/s, though.

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