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I have noticed that two cards -one CF and one SD - from the same manufacturer, with the same specifications have a significant difference in cost. The CF card costs several times more than the SD card. What is the reason for this price difference? Do CF cards have any significant advantage over SD cards in any way?

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The last time I looked at both formats, the top tier CF cards were rated for more extreme temperatures and higher altitudes than their SD counterparts. This probably has to do with their more rigid construction. This has little to nothing to do with the price disparity. That is mostly related to supply and demand. –  Michael Clark May 8 '13 at 9:25

3 Answers 3

up vote 10 down vote accepted

There is an advantage to Compact-Flash cards which you get with the fastest models and sufficiently fast camera. This is not what accounts for most of the price difference, volume is. SD cards are sold on considerably higher volume than CF ones. When CF cards were more popular, it used to be the opposite.

Nowadays, I would not worry at all about this. The most advantageous card is the one that fits in your camera! If you are choosing a camera, there are certainly much more significant differences to worry about than what memory cards they take. For a camera that accepts both, if you want the fastest get CF. If you want to replication, you will need both.

BTW, I have covered the technical differences here. They do not explain the price difference but may be interesting to know.

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The main difference in cost probably comes from economies of scale. For a long time SD cards were more expensive, but now they've become cheaper as they've become easier to manufacture and require less materials. Meanwhile, due to their bulk, consumers have fallen out of favor with CF and prefer SD.

Additionally, the architecture of the cards is different. For SD, the controller for reading the card resides in the reader and thus readers cost more but cards cost less (but are limited by the reader). For CF on the other hand, the controller resides in the card. This allows for some interesting things like the old Microdrives that were actual hard drives inside a CF card. There were also devices like wifi modems and barcode scanners built in to CF cards. Since the controller resides in the card however, it means extra expense in the production of the cards. The faster the card, the better the controller has to be and the bigger the cost difference to a comparable SD card.

As far as which is better, it really depends on the two cards and the reader being used.

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"There were also devices like wifi modems and barcode scanners built in to CF cards": how come eye fi cards dont exist for CF, but do for SD? –  Michael Nielsen May 7 '13 at 17:22
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I don't the part about controllers is correct. That's true for xD (and its ironically-named predecessor SmartMedia), but not for either SD or CF. The SD interface acts as block storage. (A better controller is one of the things that can make more expensive SD cards better, incidentally.) –  mattdm May 7 '13 at 17:24
    
@MichaelNielsen - that's a good question. My guess is that there isn't enough of a CF market anymore. In their time an awful lot of devices existed for CF though. –  AJ Henderson May 7 '13 at 17:41
    
From wikipedia "CompactFlash IDE mode defines an interface that is smaller than, but electrically identical to, the ATA interface. The CF device contains an ATA controller and appears to the host device as if it were a hard disk" –  AJ Henderson May 7 '13 at 17:52
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Riiight, but the SD Card also has a controller built in, just not an ATA-compatible interface. You need a specialized adapter on the host if you want to, for example, boot from the card, but that's not relevant to cameras. –  mattdm May 7 '13 at 17:55

Compactflash cards are much more sturdy. SD cards flex and get squashed, so unless you have them on your camera (like if you carry extra like most serious photographers) it is much better to use CF cards. They also have better bandwidth with more pins, but mostly you wont notice that since the camera interface and cardreaders cannot fully utilize it unless you get the best of the best gear. You can get 10$ cardreaders and 50$ cardreaders, and you really feel the difference. I had a sandisk extreme III CF card and used a 10$ reader, and the transfer time was 1.5mb/s. Then I got a sandisk extreme reader for 50$ and suddenly it was 20mb/s. The studiness feature is so high a priority for me that I look for the CF slot in camera specs as a dealbreaker kinda thing. Ive had too many SD cards break , and seen other people complain that all their confeirence shots were lost on a sd card, that I avoid them. I've never seen a broken CF card. Not that I claim it cant happen, just that the frequency is so low that I havent encountered one, in the same time I encountered multiple broken SD cards.

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re bandwidth - I just bought an SD card with claimed "Up to 95 MB/s" performance. (Sandisk Extreme Pro 8 GB). Actual transfer rate unknown. It cost 50% more than their 30 MB/s (claimed) card and was bought to assist in troubleshooting specific camera problems. FWIW - even if the camera could write that fast it would not keep up with my A77 max rate of 12 x say 12 MB Ultrafine JPG frames/second. | Tries it: Wow! 14 frames, 182 MB in just over one second. Buffer cleared in 4 manually counted seconds for about 45 MB/s. Some more formal tests are in order ! :-). –  Russell McMahon May 7 '13 at 21:53
    
Breakage: I find that micro SD to SD adapters break far too easily. On full size SD card leading corner can break. Will not insert without repair. Write protect sliders can vanish - must replace to write. // CF - never a problem mechanically. –  Russell McMahon May 7 '13 at 21:55

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