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CF card speed?

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by Alexandre Vaz on Sun May 23, 2010 6:16 am

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Hi all!

I'm just another stills photographer who's also taking the plunge into the video footage thing.
I'm no action photographer and I never felt the need for the fastest CF cards. Recently O got myself a 8GB UDMA 60MB/s SanDisc card that I've been using for some video footage experiments, but I will obviously need more and bigger cards. As you know fast cards are way more expensive then relatively slower ones. I can live with slower transfer speed to the computer, so the question is, how slow can I go before I start having dropped frames and other problems? Is it a 30MB/s card to slow for video footage?

Thanks in advance.

Alex

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by liquidstone on Sun May 23, 2010 7:36 am

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30 MB/s (200x) is fast enough for the 1080p video of current EOS DSLRs. I've used a Sandisk Extreme 16 GB 30 MB/s for over a year now and it works well (I'm using a 5D2 and 7D).

Romy Ocon
[url=http://www.romyocon.net/][b]Wild Birds of the Philippines[/b][/url]

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by Alexandre Vaz on Sun May 23, 2010 9:00 am

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Thanks Romy.

Does the 200x means that it can record/playback 200 times faster than real time? What is the relation between 00x and MB/s?

Thanks

a

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by Kin Lau on Sun May 23, 2010 7:27 pm

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200X means 200 times faster than 150K (yes Kilobytes) which is the old CDROM speed. So 200x basically is 30MB/s.

Many users have reported success with the Kingston 133x series. I have a 32gig AData with no speed markings (less than $100-) that works just fine for video. Any UDMA card will work, I have the Sandisk Extreme III 30MB/s, AData UDMA and Patriot UDMA.

You won't get drop frames or any such wierdness if the card is too slow. You'll simply see the buffer filling up, and then video will just stop.

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by liquidstone on Mon May 24, 2010 3:37 am

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Agree with Kin, 1x = 0.15 MB/s. Some card manufacturers put on the label either the 00 MB/s or 00x rating. Knowing the conversion factor helps in determining whether a card has fast enough write speed to take a 1080p video. IIRC, the 1080p *.mov of EOS HDV is about 44-45 mbits/s, or roughly 5.5 - 5.6 MB/s. You probably need some extra headroom, so 20 MB/s or 133x should be fast enough.

Romy Ocon
[url=http://www.romyocon.net/][b]Wild Birds of the Philippines[/b][/url]

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by Alexandre Vaz on Mon May 24, 2010 4:06 am

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Thanks, after filling my faster card I just used an old 15MB/s SanDisk card and apparently it worked fine, but I only made small clips with rarely over a minute. Maybe I could have problems if I were shooting longer clips.

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