View Full Version : 2GB Sandisk CF Extreme III & 20D write times

Theo Wallis
May 3rd, 2007, 03:01 AM
I'm just curious as to what other people have as write times for this combo of card & camera.

If I set my 20D to RAW, manual mode, iso 100 and lens cap on and take 6 raw images in a 6 frame burst it takes about 9.8 seconds for the buffer to write to the 2GB extreme III compact flash card. Timing started when the red led on the back of the camera lit up and stopped when it went out. I'm aware of the "write times " table on Rob Galbraith's site but that gives transfer times in MB/sec. Not the actual time taken to write to the card.

I just have to satisfy my own curiosity so whoever responds - thank you!

May 3rd, 2007, 04:02 AM

Divide 8 (approx raw size mb) by write speed and multiply by 6 (buffer no)

So 8 / 5.896mb/sec * 6 = 8.14 sec,

Picture content will vary raw size, I have some 20D raws as small as 6.5mb and others at 8.8mb. So the write timings could fluctuate between 6.5 and 9 secs.

Hope this helps.

Theo Wallis
May 3rd, 2007, 04:30 AM
Ahh I was looking for the average size of 20D raw files. Thanks ;o)

Alan T. Price
June 3rd, 2007, 03:36 PM
My 20D raw files range from 6.5MB to 12.5MB each. Apart from the amount of scene detail the size is affected by the amount of image noise, which in turn is affected by the ISO. Just change your camera ISO to see a change in the estimated shots remaining for your card.

I can't say how long it takes to write to card because I tend to shoot and then do something else while the camera churns away, and because I use the 1D2 more than I use the 20D. It does seem from what I have read that the camera is the limiting factor and the extreme 3 card is about the same speed as an ultra 2 card. Even an extreme iv card won't be much faster in the camera.