UDMA cards for 7D?

Boz

Boz

Well-known member
I keep hearing conflicting reports as to whether UDMA cards are needed for 5Dii/7D when shooting video. Even Canon rep Tim Smith said at Digtial Cinema Society to use UDMA when shooting video. So, what's the word? I guess to be safe I should return my Extreme III's for IV's, but I'd hate to spend the extra $$$ if it's not necessary.

By the way, the talk Tim gave was very informative. He goes into detail as to why the 5Dii had video, what Canon's response was to the demand, and even answers some questions regarding 5Dii and 24P. I highly recommend for those who haven't seen it: http://www.digitalcinemasociety.org/content.php?page=Lighting Workshop (second group of videos down)
 
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I'd take the Canon reps word. Definitely pricier but I'd err on the side of overkill. 8 gig UDMA's are selling for about 100 bucks. When compared to the price of P2 the UDMA's are pretty affordable.
 
from what i can understand, udma is needed for being able to efficiently snap a still while recording video, or to achieve high fps when shooting stills. from the user manual of the 7d you need cards with at least 5mb/s. which those extreme III's are more than enough. i just bought some kingston 16gb 133x cards to shoot with the 7d, which is the extreme III equivalent.
 
Yeah, I'm getting the same sense. Better safe than sorry. I guess I'll call Adorama to arrange an exchange.
 
Here's the quote from Tim (in July of this year):

"Is everybody here using UDMA cards, specifically UDMA cards when they get their compact flash cards? If you're not we're running into some real technical issues. It's showing some artifacting and some things that are not our fault. Stick with the UDMAs. A lot of the banding issues we were seeing on a lot of the shoots only showed up with the non-UDMA cards... ...What we think what happens is with the non-UDMA cards the camera can sense the speed of the card and it kind of dumbs down the data into the card which is causing some issues. It's our best guess at this point. But with UDMAs it's not an issue."

So it seems that slower cards will work. But quality may suffer with less than a UDMA card.
 
Its seems odd to me that a card with a maximum write speed 3x the maximum write rate of the camera would perform better than one with 2x the maximum write rate...I wonder how that works?
 
Hmmm... after further investigation there are in fact TWO kinds of SanDisk extreme IV cards! 'Regular' IVs have 40MB/s rate, while UDMA's have 45MB/s rate. Guess which ones I accidentally ordered? Yep, now I have to return two different sets of cards. Cripes. Buyer beware!
 
Before we believe exactly what Canon is saying we should definitely find someone with a UDMA card willing to do a test.

The need for UDMA cards doesn't quite add up in my mind. Theoretically anything pushing 10 MB/s should be more than enough, unless the camera is doing some sort of buffer situation. I have been using the kingston 32GB 133x since I got my 5d and haven't had problems yet. My friend has a 4gig sandisk IV and the only difference is that his can take photos without stopping video.
 
i just saw that video tom guillete posted with his insane arsenal of rented 5d's and other various lenses and equipment. all of the CF cards he rented were the extreme III's. i'm going to test one of my 16gb 133x cards extensively when i get my 7d and see how it goes. i've read a lot of users having no problems with non udma cards.
 
I may get a 16GB Sandisk III UDMA but I'm going to hang on to the Kingston 32GB 133X for the 640x480 29:59 work...that's four hours of SD recording. Also, realizing I don't know what I don't know, I still doubt the camera can sense how fast the card is writing and degrade the codec to match (I would sure like to read an explanation of that one). And the Kingston is twice as fast as it needs to be. I can't imagine that I'd ever be trying to snap stills while I'm recording video anyway...
 
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