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View Full Version : SD vs CF card. Which one is faster?



greekly
01-05-2005, 11:54 AM
Hello, everybody,

I have a question which might be a bit silly so bear with me. Are some card formats faster than the other? The reason I ask is that I currently own Nikon Coolpix 4500 which uses CF type card. It's very slow taking pictures (could be a few seconds before I press the button and the picture is actually taken) and uploading them to the card (sometimes it even "locks" for a few seconds after the shot). Has it something to do with the card or it's more an issue with camera's internal processor? I would think the later, but from the reviews it seems that the card also plays its part. Folks with CF-type of cameras seem to complain a lot about its speed, while people with SD describe their cameras as "fast".

Is this just my impression, or, indeed, cameras which use SD are faster than CF ones?

David Metsky
01-05-2005, 01:05 PM
It's very slow taking pictures (could be a few seconds before I press the button and the picture is actually taken)
This has nothing to do with your memory card, it has everything to do with your camera and the way in which you are taking pictures. Some cameras have much less "shutter lag" due to their design, and you can pre-focus your camera to cut down on the processing the camera has to do before taking the shot.

and uploading them to the card (sometimes it even "locks" for a few seconds after the shot).
This may or may not be related to the card. Some cameras "lock" while writing to the card, a very annoying feature. Not sure it has anything to do with card speed, though.

Has it something to do with the card or it's more an issue with camera's internal processor? I would think the later, but from the reviews it seems that the card also plays its part. Folks with CF-type of cameras seem to complain a lot about its speed, while people with SD describe their cameras as "fast".
I think it is more a design of the camera, having nothing to do with the cards. After all, the fastest cameras out there are dSLRs and nearly all use CF. It may be that more newer cameras are using SD and they tend to be faster than the older cameras, more of which used CF.

arghman
01-05-2005, 03:13 PM
1) the theoretical maximum of SD is 100Mbits/sec = 12.5Mbytes/sec (25MHz max clock rate x 4 bit databus) minus some communications overhead. CompactFlash has more pins (16-bit databus) & the CompactFlash consortium FAQ (http://www.compactflash.org/faqs/faq.htm) claims 16MB/sec (128Mbits/sec) so it's slightly faster theoretical maximum but not by much.

2) Camera speed -- some cameras are faster than others (what David said). My old Kodak was slow as a dog.

3) card speed -- do you have a fast card? there's a wide range of card speeds (I didn't know this until I started looking around); there are some benchmarks on the Web. But you should find out whether your camera's the bottleneck before you go out & buy a fast card.

UberVamp44
01-09-2005, 12:59 PM
The speed in which the camera rights to the card is judged by the camera and the size of the picture and the card cable write speeds you can by different write speed CF card such as 4X,40X,80Xand I think there is one higher and whith each upgrade speeds are faster mainly the speed in which a camera write in up to the camera cuz most cards can handle the information much more quickly than the camera can right it

ProblemSolver
01-21-2005, 05:37 AM
Personally, I think SDs (Except Sandisk Ultra II and Extreme III SDs) are slower than CF cards. There must be some tradeoff to make SDs smaller than ever - Same with memory sticks. If SDs are smaller than CF cards, then why aren't they ruling and taking over CF cards? SDs which are small in size are slower (Although may not be noticable instantly) than CFs. MMCs are certainly slower than SDs.

arghman
01-22-2005, 11:47 AM
Sure, there's a tradeoff -- SD cards have fewer pins. More pins means more information that can be sent at the same time; as I posted earlier, CF = 16-bit databus, SD = 4-bit databus.

But the SD card standard is more recent and I believe it takes advantage of synchronous memory bus technology (there's a clock signal & that can help increase throughput, though I'm not sure of the details), whereas I'm fairly sure that CF cards use an asynchronous memory bus (typically you get your data signals ready, then you pull a write line low for a short period of time).
If the CF and SD standards had come out at the same time & used the same techniques, CF would win because it has more pins for speed and more volume to put larger memory chips. But CF is an older standard, and once you have a standard, some of the technology is "frozen" in order to adhere to the standard & can't take advantage of newer technological advances.

Sorry if that's getting a little over-technical... my guess is that SD cards will take over a larger share of the market as time goes on (until a new standard comes out), but CF will be around for a while because there are so many devices that use it (and it's a more robust package).

i86i11
01-03-2008, 12:24 PM
This is an old thread I know but it came back number 1 in my google search of "cf vs sd" so I figure I'll give it a good update for anybody else that stumbles on it.

Please see this link to wikipedia with a great comparison of the different cards and their speeds, capacity, etc. (Click Here (http://en.wikipedia.org/wiki/Comparison_of_memory_cards))

Thanks.

erichlund
01-04-2008, 10:13 AM
This is an old thread I know but it came back number 1 in my google search of "cf vs sd" so I figure I'll give it a good update for anybody else that stumbles on it.

Please see this link to wikipedia with a great comparison of the different cards and their speeds, capacity, etc. (Click Here (http://en.wikipedia.org/wiki/Comparison_of_memory_cards))

Thanks.

This brings up a question I have. I've bought a couple of items lately that use SD cards, but specify a maximum card size. If the cards have their own controller chip, why is there a maximum? With CF, the controller chip on the card takes care of memory management, so the maximum is whatever is on the card.

K1W1
01-04-2008, 05:07 PM
This brings up a question I have. I've bought a couple of items lately that use SD cards, but specify a maximum card size. If the cards have their own controller chip, why is there a maximum? With CF, the controller chip on the card takes care of memory management, so the maximum is whatever is on the card.

I would have thought that you would already know the answer from your time on Nikon forums.
The maximum size of the card is determined by the file system that the writing device uses. Older cameras like D50 use FAT16 so the maximum usable size is 2GB - this is determined by the limitations of FAT16 not the card or the device.
Newer cameras like D40 use a 32bit FAT system so that can use cards in excess of 2GB capacity because the file system allows that.
Then there is the issue of SD and SDHC cards. Whilst the cards are physically the same size they are different so devices designed for the older SD format cards (generally less than 2GB) cannot use the newer SDHC cards (generally greater than 2GB). Newer devices are backwards compatible so a device that allows SDHC will work with SD.