What CF card for 40D

I have looked around for Specs cannot find any

is there any benefit to using sandisk Extreme IV CF card over the III on a 40D, I know it is better to use the IV on the MK 3, but just wondered what Speed the R/W is on a 40D to the CF card

III records data at 20MP/sec, IV at 40. If you use III with burst mode (6.5 shots/sec) you need to make sure your resolution creates images that are less than 3MP (20/6.5) in size. I think that's how it works.

shutterfiend wrote in post #3899452
III records data at 20MP/sec, IV at 40. If you use III with burst mode (6.5 shots/sec) you need to make sure your resolution creates images that are less than 3MP (20/6.5) in size. I think that's how it works.

Not really,

The camera has an internal buffer large enough for 17 raw at the highest resolution so you can always shoot a series like that. Directly after taking the first shot data will start being transferred to the card. When the internal buffer is full the FPS will decrease to the speed images is transferred.

It does thus only affect the speed after image #17 in the burst and once it gets to rest for a few seconds it will empty the internal buffer to the card and be ready for a new full burst.

If you shoot jpeg the internal buffer will hold up to 75 according to specs.

but after buffer full is it not all dependent on the actually transfer rate of the camera to the CF card, that is what I need to know

Have a look on this:

http://www.robgalbrait​h.com …ti_page.asp?cid​=6007-8478

and you can get the idea. It's based on 30D, but you can choose other cameras and card readers to compare.

IMHO you can feel the real difference in CF to PC transfers, but only if you use a very fast card reader that make full use of IV's DMA mode.

I just recall comments that it made a difference to the MK3 but not to the 30D. their was no point going above Sandisk III, but wondered if the 40D was same as MK 3 speed for moving data to the CF.
Do not want to go get a Sandisk III when I would be better off with a IV, at same time Peak do a very fast CF now that is speed wise in between a III and IV

PEAK 8GB COMPACT FLASH MEM XTREME 120x RET
£56-50 + VAT

Warranty 5 Years
Capacity 8GB
Interface Compact Flash
Read Speed 18MB/s
Write Speed 8MB/s
Operation Voltage 3.3V / 5V
Insertions 10,000
Special Features Error Correcting Code (ECC)
System Programming (ISP)
Wear Leverage function
Low Power Consumption

Damm found this one though only 4 Gig £35-68 + VAT

Product Group Flash Memory
Manufacturer PEAK
SKU 284612
Product Name PEAK 4GB COMPACT FLASH MEM XTREME 266x RET
Web Address www.peakhardware.com.t​w
Model Number 284612FBPK
Package Type Retail
Warranty 5 Years
Capacity 4GB
Interface Compact Flash
Read Speed 40MB/s
Write Speed 30MB/s
Operation Voltage 3.3V / 5V
Insertions 10,000
Width 42.8mm
Height 3.3mm
Depth 36.4mm
Weight 11.4g
Special Features Built-in Dynamic Defect Management and Error Correction Technology
High Transfer Rate for Fast Copy or Download
Low Power Consumption
Read Speed: 40 MB/sec and Write Speed: 30 MB/sec

i'm using extreme III's in my 40d, i shot over 400 shots at the weekend [1st chance i've had to give it a decent run!] including lots of bursts, in no way did the extreme III's hold me back and i can't see that i'd get any extra benefits from paying more for extreme IV's..... i shall probably pick up a couple more 4gig extreme III's soon, there such good value now - Play.com £36.99 delivered.

note.... I did no scientific testing, just my regular shooting at an event - i just don't feel the exteme III's hold the 40d back in anyway [So far.....]

Amazon UK had them for £31.95 but with postage to pay. So not sure which is the absolute cheapest

Picstop have them at £36.40 inc VAT and delivery...

The Sandisk Extreme IV cards achieve their highest transfer rates by using UDMA. If the camera doesn't support this, then using Extreme IV cards won't give you much of a speed increase over Extreme III, and AFAIK the 40D doesn't use UDMA. Of course this is all theoretical; best to wait for Rob Galbraith to update his database with 40D results.

The question is, do you ever see yourself being limited by the 17 RAW image buffer of the 40D? Unless you're a spray-and-pray type of guy, you'll be shooting in short bursts even when shooting action, so the buffer should be big enough to handle the shots without filling up as long as you use a fast card like the Extreme III.

everything i ever bought off play before was free delivery anyhow