This is where Ian Burley, DPNow's editor and founder, shares his unique thoughts and impressions on subjects that he hopes will be of interest to others on the subjects of digital photography and other related or loosely related topics! You can follow DPNow Editor's blog on Facebook and Twitter, too.
1000x compact flash memory cards - are they too slow?
Lexar today announced a new range of 1000x Lexar Pro compact flash memory cards. Theoretically these cards can transfer data at 150 megabytes per second compared to 90MB/sec for its 600x cards and 45MB/sec with its 300x cards. When card capacities reach as much as 128GB, you need fast transfer speeds simply to read your photos and video off the card without finding you have (more) grey hair at the end of the process. 150MB/sec means a wait of at least 15 minutes to read the entire contents of a 128GB card. At 600x you would need to wait almost another ten minutes.
Card performance is also increasingly important inside the camera too. As sensors get more and more pixels, the sheer volume of data that needs to be swallowed up during high-speed shooting is phenominal, requiring large buffer memory capacities. If your card is too slow you also risk dropped frames when shooting video. If faster transfer rates are guaranteed you can reduce video compression and boost video quality.
Lexar and other card manufacturers now utilise an extension of the Ultra Direct Memory Access (UDMA) interface standard, which now reaches Mode 7 (UDMA 7) and covers the fastest UDMA devices exceeding 133MB/sec (UDMA 6). But UDMA was invented ages ago for computer hard disk drives and has long since been replaced by a more efficient and performance-scalable solution called SATA (Serial ATA). UDMA and compact flash, which itself has been around for almost 18 years, are based on less efficient parallel data transfer technology. UDMA 7 represents the practical limit for parallel interface storage technology of its type. Inevitably, a serial data transfer replacement would appear on the horizon and signal the beginning of the end for the development of compact flash as we know it.
That new hope is called XQD and its standards and development, interestingly, are the responsibility of the CompactFlash Association after being originally conceived and proposed by Sandisk, Canon and Nikon. XQD is a memory card standard that is designed to work intimately with the extablished PCI Express serial data bus standard now widely found in computers and other devices. PCI Express exists in many guises but the most common forms offer transfer rates of between 250MB and 500MB/sec over an individual 'lane'. Aggregate a number of lanes and you can achieve multiples of these figures.
XQD cards are scheduled to start shipping this year and are initially expected to offer around 125MB/second write and 250MB/sec read speeds. Lexar's 1000x CF cards should, under ideal circumstances, be read at 150MB/sec, 100MB/sec slower than the first XQD cards, but Lexar doesn't say what the write speeds are for the 1000x cards. This suggests that the write speed is significantly slower than 150MB/sec and probably slower than the 125MB/sec speed we can expect of XQD cards.
But Lexar does have a few aces of its own. Compact flash cards are widely supported, even if few cameras actually support UDMA 7 maximum performance. XQD is a completely new standard and although the cards are 25% smaller than CF cards, and more robust than SD cards, there are - at the time of writing - no cameras on sale that can take XQD cards.
I don't expect XQD will be widely supported in domestic and consumer devices. SD and its SDHC and SDXC cousins have this end of the market tied up for a long time to come. But if you are a professional photographer, especially in the area of action and sports photography, or a videographer, then the letters XQD could well be an everday utterance in the not too distant future.
Total Comments 0