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SD vs CF
- Thread starter Dolby
- Start date
CF cards still have higher transfer rates than SD cards. That's about it. Check Rob Galbraiths page for a huge comparsion of CF and SD/XQD cards http://www.robgalbraith.com/bins/camera_wb_multi_page.asp?cid=6007-10549
I'm by no means an expert on the topic but from what I've read:
The interface on CF uses 50 pins vs 9 pins on SD.
This means that CF can transfer 16 bits per read/write operation vs 4 bits on SD which is one of the reasons why SD is slower.
SD would need to be clocked 4 times faster to match CF transfer rates however that is not the only contributing factor.
The speed of the flash memory controller on the CF and SD cards is also a contributing factor.
The gap between CF and SD has narrowed substantially and I wouldn't be surprised if CF support is dropped once (if) SD speeds reach those of CF. Sort of like the IDE vs SATA hard drive situation. IDE uses a parallel interface which means more bits per read/write cycle but ultimately SATA with it's serial interface triumphed once the transfer clock speeds where increased enough.
Try find a new IDE hard drive nowdays.
The pros of SD are a much better physical interface than CF.
With SD there is no risk of bending the pins in the slot of your freaking expensive, full frame camera.
Bent or broken pins in a CF slot can cause much grief to the wallet.
The interface on CF uses 50 pins vs 9 pins on SD.
This means that CF can transfer 16 bits per read/write operation vs 4 bits on SD which is one of the reasons why SD is slower.
SD would need to be clocked 4 times faster to match CF transfer rates however that is not the only contributing factor.
The speed of the flash memory controller on the CF and SD cards is also a contributing factor.
The gap between CF and SD has narrowed substantially and I wouldn't be surprised if CF support is dropped once (if) SD speeds reach those of CF. Sort of like the IDE vs SATA hard drive situation. IDE uses a parallel interface which means more bits per read/write cycle but ultimately SATA with it's serial interface triumphed once the transfer clock speeds where increased enough.
Try find a new IDE hard drive nowdays.
The pros of SD are a much better physical interface than CF.
With SD there is no risk of bending the pins in the slot of your freaking expensive, full frame camera.
Bent or broken pins in a CF slot can cause much grief to the wallet.
koffiejunkie
Executive Member
What do you base that on? The figures from Rob Galbraith's site shows the fastest write speed for SDHC being 20MB/s, while the fastest CF cards write 66MB/s. That's more than a gap. Yes, SD cards have gotten faster, but CF cards have advanced just as much, if not more.
jip, I have read a few blog post posts by togs covering the Olympics, they all seem to be using the new Lexar 1000x 128Gb CF....!!! I do not want to know how much they cost...
Just for interest sake, go look at Rob Galbraith table for the D4 and the new XQD cards, they seem to be lightening quick! I think they will replace CF before SD replaces CF...
koffiejunkie
Executive Member
Yes, but XQD is not SD.
Seems you're right. I didn't realise that CF had advanced so far.
I remember buying a Sandisk Ultra card back in 2002. The maximum sustained write speed was 2.8 MB per second and even then it was slow.
Has XQD sorted out the woes of CF's physical interface?
Both those figures sound way too low. I've got a UHS-I SD card that can do at least 40 MB/s (out of claimed 45 MB/s), and even that card is not the best example of UHS-I SD cards. I recall that some UHS-I cards can actually achieve closer to 90 MB/s.
But the CF cards are still faster; I seem to recall figures of over 100 MB/s on current state-of-the-art CF.
(Not sure whether my figures are in a camera, or in a fast card reader, though)
Sorry for not provinding any links/proof, but I am a bit lazy today.
koffiejunkie
Executive Member
I don't know. I consider the physical interface "problems" vastly overstated. For one, the CF card is guided into the camera, so you have to be pretty deliberate to screw it up. You only real problems is getting something foreign stuck in the slot and damaging the pins, or if you have a cheapy card read that doesn't guide the card.
For the getting-something-stuck-in-there problem, you deserve what comes your way if you let your camera sit around with the flap open. The only incidents I've read about where something did get stuck, it has always been a bug crawling in and getting squashed on the pins. No damage to the pins, no damage to the cards, just a hassle getting it cleaned out.
For the cheapy cardreader problem, my sandisk 12in1 has this problem. It has guides but they're not tight enough. I can conceivably bend the pins in the card reader, but seriously, if I put it in wrong, it just doesn't sit right, and I know to pull it out again. So again, things break when you force them despite the feedback that something is not right. The same problem exists on the SD card, to much worse extent.
I am hideously clumsy, and even I haven't managed to damage a CF card or the CF cards slot even on my cheapy card reader. So as far as I am concerned, this problem is one of those rare things that a few vocal idiots on the internet blow way out of proportion.
RG's figures are specific to the camera. Back when I had the Sandisk firewire reader, it read and wrote much faster than my 40D did. I believe the Lexar USB3 card reader will perform better than any camera on the market right now, but of course, it has little relevance for where you actually use your cards, i.e. in the camera.
How do you not know weather your cameras are in camera? Surely getting those figures in the first place is a process that's pretty hard to forget? (I don't even know how to go about it!) Or are they not your figures?
GarethC
Well-Known Member
I must agree with you here. I've had my camera for the past 4 years, and regularly replace CF cards in and out of the camera and in and out of a cheap card reader. I've also read about people having damaged the pins, but don't think I've ever come near to doing that.
I know my camera and I know how easily the CF cards slide in, so the moment it doesn't feel quite right I stop.
Sure the SD cards physical interface is "better", but the CF card's interface isn't bad.
I have managed to have a pin fold in on a Fuji camera. Was not forcing the CF card at all. Was just calmly sliding it in and it had reached the end. When I tried to turn the camera on, it started complaining about the card not being readable.
I opened her up, saw that a pin had bent inwards, and left it for a while. Fuji quoted something like R5k for repairs (had to replace the whole board). Luckily I managed to find a service manual, open the camera up, and had people who I could ask to solder a new connector on. Since then it has been working perfectly again, but would prefer to avoid a repeat of that, so I keep my CF card in the D300s at all times. I only ever pull out the SD card if I need to.
I opened her up, saw that a pin had bent inwards, and left it for a while. Fuji quoted something like R5k for repairs (had to replace the whole board). Luckily I managed to find a service manual, open the camera up, and had people who I could ask to solder a new connector on. Since then it has been working perfectly again, but would prefer to avoid a repeat of that, so I keep my CF card in the D300s at all times. I only ever pull out the SD card if I need to.
koffiejunkie
Executive Member
Which one do you have? I'm thinking of replacing my USB one - it's slow as molasses.
I used to have the Sandisk Extreme FW400 one, which was lovely, but was in my camera bag when it went missing. That reader was perfect for me, it was very compact, and could read the three cards types I had - SD, MemoryStick Pro and CF. They're not made any more and when they come up on eBay they sell for upwards of £100
Lexar Professional - don't think they make it anymore - good thing I have two.Which one do you have? I'm thinking of replacing my USB one - it's slow as molasses.
I used to have the Sandisk Extreme FW400 one, which was lovely, but was in my camera bag when it went missing. That reader was perfect for me, it was very compact, and could read the three cards types I had - SD, MemoryStick Pro and CF. They're not made any more and when they come up on eBay they sell for upwards of £100
I appologize for the confusion, but I used the term "my figures" rather loosely, meaning the figures I quoted. In any case, I went ahead and did some tests with the Sandisk Extreme Pro UHS-I 16 GB card in a D7000.
The method is rather unrefined, but certainly good enough to obtain ballpark figures. I set the camera to 6 fps burst, manual exposure at 1/250, manual focus lens, 14-bit RAW + JPEG fine, shooting a flat field.
Then I start a burst capture, which I keep up until the internal buffer fills up. I timed (manually) from the moment the shutter was depressed, until the green "card busy" light went out. I then calculate the size of the 18 files captured in the burst. If I shoot in RAW only, the light does not stay lit continuously, but rather blinks, which means that a more complex scene (lower compression, RAW + JPEG) would probably push the figures slightly higher, but not much, since the active capture part is only about 1.5 seconds out of the total time of 7 seconds (flushing the buffer to card).
This gives me a figure of 22 MB/s (+- 2 MB/s), which seems consistent with RG's figures.
The same card can achieve about 36 MB/s write performance in a card reader (http://www.tomshardware.com/reviews/sdxc-sdhc-uhs-i,2940-7.html).
I could not perform a similar measurement for CF, since I have no CF devices!
Anyhow, this points to an interesting problem: the D7000 is certainly the bottleneck (which also explains why the Sandisk Extreme III 30 MB/s card performs the same as the Extreme Pro UHS-I card).
We know that the UHS-I interface is capable of either 50 MB/s (most likely mode supported by D7000), or 104 MB/s. So this means that the SD card is not really the bottleneck, rather that higher-end bodies capable of higher write speeds tend to implement the CF interface instead of SD.
Someone with a D800 could probably provide us with an interesting comparison in this respect.
Rouxenator
Dank meme lord
Just curious, are they still making microDrive CF cards these days or has CF gone completely flash based?
I don't see CF dying anytime soon, despite its IDE compatible interface. Its a more robust card than SD and you can fit more inside it than you can in the SD form factor. If it ever does get replaced by another format it will most likely be microSD.
I don't see CF dying anytime soon, despite its IDE compatible interface. Its a more robust card than SD and you can fit more inside it than you can in the SD form factor. If it ever does get replaced by another format it will most likely be microSD.
As of July 2012, no manufacturers seem to be making Microdrives.
http://en.wikipedia.org/wiki/Microdrive
Rouxenator
Dank meme lord
What a pity, then again they were pretty useless towards the end considering the massive progress made by flash memory.
Guess I'm just nostalgic I still recall replacing the microdrive inside an iPod Mini with a CF card... many years ago.
Guess I'm just nostalgic
I still recall replacing the microdrive inside an iPod Mini with a CF card... many years ago.koffiejunkie
Executive Member
Nice work! I suspect RG's tests is done in a similar way, maybe with some refinements.
I'll try it with the 7D and the cards I have. I don't have any of the modern fast cards, so I'm not sure what will be be the bottleneck - camera or card.
I'm not sure I follow. If your camera supports UHS-I at 50MB/s, and you have a UHS-I card that's good for 36MB/s, and you're only getting 22MB/s between the two, how can you tell that the bottleneck is the camera and not the card, or vice versa?