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Old Feb 23, 2008, 1:01 PM   #1
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Hey guys, I'm new here and I basically registered for one question, although I know I will be back often to learn. Here it is : I'm planning on purchasing a Canon TX1 very soon (for a major trip to Europe), and I'm not sure which SDHC card to buy. On Canon's web site, they recommend a card with a nominal writing speed of 20mb/sec., but I can't seem to find that info anywhere for any of the cards I look at on web stores. For instance, would a Transcend 16gb SDHC Class 6 be fast enough? Or should I go with a Sandisk Extreme III? What about the Patriot?

I'm mostly interested in 16gb cards because recording in 720p requires a lot of space and I also need to take pics so I'll need LOTS of space. I'll probably end up buying 2 or 3 16GB cards, but I want to make the right choice (speed- andreliability-wise).

Thanks a bunch for your help!

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Old Feb 23, 2008, 9:23 PM   #2
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The PowerShot TX1 Camera User Guide Advanced says that it can record continuous video onto a "Super high speed SDC-512MSH memory card".

Unfortunately, only Canon knows what "Super high speed" means. I didn't see a reference to "20mb/sec." anywhere, but that doesn't help. First, the lower case 'm' is wrong. A lower case 'm' is 'milli' which means one thousandth (1/1,000), where as an upper case 'M' is 'mega' which means one million (1,000,000). So I'm certain that it should be an upper case 'M'. But the 'b' could be either a 'b' meaning'bit',or a 'B' meaning byte. That would make the specification either 20Mb/sec, or 20MB/sec which is 8 times greater, since there are 8 bits in a byte. The 'X' values we often see associated with flash memory card speeds are borrowed from CD-ROM drives, where a standard music CD drive transfers information at a rate of 150,000 bytes per second (150KB/sec) A 20MB/sec card would be 20,000KB/150KB, or a 133X card. I don't know how fast Canon thinks a "Super high speed SDC-512MSH memory card" is, but 133X is pretty fast. On the other hand, if the specification is actually for a 20Mb/sec (20 megabits per second), that would be 2,500KB/150KB, or a 16.7X card, which is actually pretty slow.

As to the Transcend 16GB SDHC Class 6 card, Class 6 cards can transfer data at up to 6MB/sec. which would make it a 40X Card, a moderately fast card. Definately faster than 20Mb/sec, but not as fast as 20MB/sec.
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Old Feb 23, 2008, 9:32 PM   #3
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OK thanks a lot for that specific info. I'll have to dig deeper into this because I really don't want to buy cards that won't be fast enough for the TX1.

Thanks again!
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Old Feb 23, 2008, 9:48 PM   #4
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One thing you may want to also consider is if you know you'll want to take a ton photos while in Europe is that you may want to invest and carry a Wolverine (or other manufactor)memory card/hard disc storage device. They allow you to upload the contens of your memory card to it and then reuse your memory. They come in 40 - 160GB models.

I own the Wolverine 60GB model and used it twice so far for trips and it has worked out very well for me.It always stays in my camera bag and the camera bag goes everywhere with me. I was able to carry the AC adpator for it which allowed me to use it without worrying about the battery dying on me. Since you'll be uploading 16GB cards to ther device you should make it a point to cary the AC power cord in your suitecase and use it when you use the deviceso the battery doesn't die in the middle of a large transfer. Iwould shootall day and then off load and erase the cards at night. At the time I only had a 2GB and a 4GB card. I now have a 16GB card added to the mix.

I got this device for a trip I was taking to Baltimore (staying in hotel) and didn't feel safe taking my laptop with me and having it in the turn off my car or the hotel room when I was not around.

check bhphotovideo and newegg.com for this device and way the cost of one against getting those extra 16GB cards which you may or maynot use once the trip is over.

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Old Feb 23, 2008, 10:57 PM   #5
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TCav wrote:
Quote:
As to the Transcend 16GB SDHC Class 6 card, Class 6 cards can transfer data at up to 6MB/sec. which would make it a 40X Card, a moderately fast card. Definately faster than 20Mb/sec, but not as fast as 20MB/sec.
The SD Association defined three classes of cards under SDHC, to help eliminate some of the confusion.

Class 2: Minimum Sustained Data Transfer Speed of 2MB/Second
Class 4: Minimum Sustained Data Transfer Speed of 4MB/Second
Class 6: Minimum Sustained Data Transfer Speed of 6MB/Second


A Class 6 card may be much faster than 6MB/Second. Class 6 is just the highest rating under the new SDHC standards.

For example, a Sandisk Extreme III SDHC card is a Class 6 Card. Yet, these cards can support write speeds of up to 20MB/Second.

See the Performance section on this Sandisk Page for an example. Note the Class 6 rating.

Sandisk Extreme III SDHC Card
  • Capacities available: 2GB to 8GB[/*]
  • SD and SDHC Card: Minimum 20MB/ sec sequential read/write speeds*[/*]
  • 4GB and 8GB SDHC cards includes a bonus MicroMate Reader[/*]
  • Speed performance rating: Class 6 (based on SD 2.0 specification)[/*]
As for the Transcend Class 6 16GB SDHC Card, I haven't seen any benchmarks of that one yet. But, the Transcend 8GB Class 6 SDHC Card looks like it can do around 18MB/Second according to one bechmark. Another I see shows around 14MB/Second write speed and 19MB/Second read speed with larger block sizes. It tested a little faster than the A-Data 16GB Class 6 SDHC card. I don't know if the Transcend 16GB would be as fast or not. See the screen captures of the benchmarks on this page:

http://www.notebookreview.com/assets/30998.jpg

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Old Feb 24, 2008, 7:17 AM   #6
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JimC wrote:
Quote:
TCav wrote:
Quote:
As to the Transcend 16GB SDHC Class 6 card, Class 6 cards can transfer data at up to 6MB/sec. which would make it a 40X Card, a moderately fast card. Definately faster than 20Mb/sec, but not as fast as 20MB/sec.
The SD Association defined three classes of cards under SDHC, to help eliminate some of the confusion.

Class 2: Minimum Sustained Data Transfer Speed of 2MB/Second
Class 4: Minimum Sustained Data Transfer Speed of 4MB/Second
Class 6: Minimum Sustained Data Transfer Speed of 6MB/Second


A Class 6 card may be much faster than 6MB/Second. Class 6 is just the highest rating under the new SDHC standards.
Yes. You're right. Thank you. I should have said that a Class 6 card can transfer data at 6MB/Sec minimum.
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Old Feb 24, 2008, 8:34 AM   #7
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Thanks everyone for the replies. Looks like Sandisk would be the way to go. Unfortunately, there are no 16GB Class 6 available from them (yet). Hopefully they will come out with one in the next 2 months, I'm leaving for Europe at the end of May.
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Old Feb 24, 2008, 9:03 AM   #8
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Take a Picture wrote:
Quote:
Thanks everyone for the replies. Looks like Sandisk would be the way to go. Unfortunately, there are no 16GB Class 6 available from them (yet).
Any card that can transfer data at a minimum of 6MB/sec is a Class 6 card. Most SanDisk cards fall into that category. The 16GB SanDisk Ultra II can transfer data at 15MB/sec. That's Class 6 and then some.

ANd the specification for SD Card Classes lists the minimum speed of a newly formatted card. Once a card has some files on it, especially a lot of very small files, the performance degrades slightly, so having a card with alittle extra performance is a good idea, especially as the cards get larger.
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Old Feb 24, 2008, 12:01 PM   #9
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TCav wrote:
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Take a Picture wrote:
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Thanks everyone for the replies. Looks like Sandisk would be the way to go. Unfortunately, there are no 16GB Class 6 available from them (yet).
Any card that can transfer data at a minimum of 6MB/sec is a Class 6 card. Most SanDisk cards fall into that category. The 16GB SanDisk Ultra II can transfer data at 15MB/sec. That's Class 6 and then some.

ANd the specification for SD Card Classes lists the minimum speed of a newly formatted card. Once a card has some files on it, especially a lot of very small files, the performance degrades slightly, so having a card with alittle extra performance is a good idea, especially as the cards get larger.
Yet it clearly says Class 4 on that particular card...why is that? And do you think I'd be better off just buying the upcoming 32GB card from Sandisk, even if it's a Class 4?
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Old Feb 24, 2008, 1:59 PM   #10
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SanDisk says that the Ultra II SDHC Card has"Write speed: 9MB/sec and Read speed: 10MB/sec", but then says "Speed performance rating: Class 4" when the SD Card Association says "Class 4 Card: A speed of 4 MB/s or higher is guaranteed at the best fragmented state where no memory unit is occupied."

SanDisk also says that the Extreme III SDHC Card has "Minimum 20MB/ sec sequential read/write speeds", and says "Speed performance rating: Class 6" when the SD Card Association says "Class 6 Card: A speed of 6 MB/s or higher is guaranteed at the best fragmented state where no memory unit is occupied."

If the Ultra II has a write speed of 9MB/s, why isn't it a Class 6 Card? [suB]:?[/suB]
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