And.... we're back! Many apologies for the rather scant upgrades over the last few weeks. To say it's been busy would be an understatement.... and it wasn't helped by being on another continent with not much access to to internet.

 Anyway, while we've been 'off-air' I was sent an email asking about memory cards. The question was as follows:
Q: When buying a CF card (or 2) where should you put your money (if
you are like me and don't have much)? Should you get: a) large memory
cards with slower speeds, b) less memory in the card but with faster
write speeds or 3) a happy medium. The follow up to this is "How much does write speed affect video recording?"

The blog seemed like an ideal place to answer this as I'm sure others have asked the question before. 

Pretty much without exception, if you buy a reasonable memory card these days, namely a SanDisk Ultra II or faster, you will have a fast enough memory card in terms of read and write speed. The difference comes when you are shooting sport or long bursts. Here, a faster memory card will mean the camera can clear the buffer faster and hence shoot more images in a burst before buffer lock-out. With some of the newer EOS models, like the EOS 5D Mark II, EOS 50D and EOS 7D, these are compatible with UDMA Class 6 memory cards - like the SanDisk Extreme Pro range of cards. Using a UDMA card in these cameras will result in improved buffer performance.

If you don't shoot bursts, then the only real benefit to faster memory cards is the downloading speed - a faster card will give up its data to a computer quicker so you spend less time waiting for the import to happen - but if this is your concern, you need should also look at the card reader you use. While USB 2 is quite quick, if you want to make use of the fastest cards, you need to use FW800 card readers so the data can transfer to the computer faster. 

As for the effect on video, the cameras that shoot video - EOS 5D Mark II, EOS 7D, EOS-1D Mark IV and EOS 500D, need a minimum write speed of 8MB/sec. The SanDisk Ultra II manages 15-30MB/sec write speed so is more than capable of dealing with the demands of video. With a slower than 8MB/sec card, you will see a buffer signal on the rear LCD. This will gradually decrease as the buffer fills. 

So to answer the question, unless you have a need for it, you don't have to buy the fastest memory cards available. You'll find coming down the range gives more capacity for less money. From that point of view, the SanDisk Extreme III look like a very good choice at the moment - they are available in sizes up to 32GB and are a lot cheaper than going for the top of the range. 

For anyone looking at memory, I came across an interesting oddity in pricing today:

SanDisk Extreme IV 45MB/sec 16GB - £149.99
SanDisk Extreme 60MB/sec 16GB - £99.99

Yes, the faster, newer card is£50 cheaper.....!