Compact Flash data transfer rate??

[shovel66]

Hello,
New to photography and new to this forum. Recently bought my first Digital SLR camera (Canon D50) and bought a Sandisk compact flash Extreme III 4gb card to go inside. The salesperson said that I should get the one that is 30mb/s because it would be fast enough for continuous shooting as not to fill the buffer.
Now I'm looking for an additional card and am wondering if a 15mb/s would be fast enough for it. They seem to be a little cheaper and more plentiful.
Thanks.

[Frog]

The 4gb ;is the size of the card and how many shots it will hold. The 'Extreme III' part is what makes it faster, though I have no idea why. The cards speed, so I understand, helps with little except download time.
I wouldn't go to a 15mb/s though as you'll get fewer shots on the card and if you are shooting a lot, you'll have to stop to change cards.
I have 4 2gig cards and have never used them up.

[Ray Dockrey]

You can go to a slower card with no issues as long as you aren't doing continuous burst's. A 4 gig card is a 4 gig card. A 15mb/s card that is 4 gig will hold the same amount of info as a 4 gig 30 mb/s card it will just take longer to write to the card. With the camera's built in buffer it shouldn't be an issue unless you are doing continuous burst's with large files like RAW files. I have a D200 that I shoot in RAW and I use the 4 gig 15 mb/s cards with no issues. I actually have a card that is about 10 mb/s and I have no issues with that card either even if I do on the rare occasion do a continuous burst.

[Franglais]

Modern cameras have a huge internal buffer. On my D300 there is enough space for 15 RAW images. I've fitted a Transcend UDMA card to speed up the flush of the buffer to card but I don't think I'm ever going to do a burst of 15 shots.

The key term here is UDMA. This is an update to the Compact Flash standard from about 2-3 years ago which almost doubled the data transfer speeds.

For UDMA to work the card AND camera have to support it. The Canon 50D does support UDMA so you're OK. It is not a good idea to put a UDMA card in a camera that doesn't support UDMA, the result is often slower than a normal card.

The Sandisk cards supporting UDMA are the following:

- Extreme IV 45MB/s
- Extreme IV 40MB/s
- Extreme III 30MB/s
- Extreme Ducati

The Extreme III 20MB/s card doesn't support UDMA.

BTW I find a 4GB card is not big enough for a heavy days shoot in RAW on a 12MPix camera. My 8GB card is just about enough.

[readingr]

Try looking at the information on this site which test camera's and cards/

http://www.robgalbraith.com/bins/mul...e.asp?cid=6007

Roger R.

[shovel66]

Thanks for all the good info. I am still learning every time I use the camera. This morning I was doing continuous bursts with my 30mb/s card. It seemed to keep up for the photos I took. Looking at getting a second card this week. Will probably not go any slower than the one I have now, but 8gb sounds good. Haven't shot in RAW yet, but want to be prepared for when I do.
Thanks again,
Chad