The mystery behind SDHC
For those of us that use SD cards there's a new acronym floating around, SDHC. Many may dismiss this as some kind of marketing gimmick, just another way of dressing up the new batch of 4GB, 8GB and the upcoming 16GB cards. However Secure Digital High Capacity (SDHC) is far more than just bigger capacity cards, it's a whole new standard and unfortunately that means that your camera or other device probably won't be able to make use of them.
Ordinary SD cards peaked at around 2GB and even this capacity caused problems. Basically the file system that the cards used meant that 1GB was as big as they could get. 2GB was possible with a little bit of tinkering with the file system, however this tinkering meant that many devices wouldn't even recognise 2GB cards (as many people later found out). To continue to create bigger capacity cards a new standard was needed, and SDHC (or SD 2.0) was born.
The new cards also promise greater speeds with the new specification having four speed classes, although in reality there are only three as Class 0 means there is no guaranteed speed. The other classes guarantee a minimum write speed:
- Class 2: 2 MB/s
- Class 4: 4 MB/s
- Class 6: 6 MB/s
All the SDHC cards supplied by Horizon Flash Memory are rated Class 6, with a minimum write speed of 6MB/s.
With the new range of digital cameras reaching up to 12 mega pixels, the humble 1GB and 2GB cards just couldn't cut it. With a 1GB and a 12MP camera, you would only be able to fit around 150 photos on the card, hardly enough for a day out let alone a family holiday. As for video, well it was always tight fitting DVD quality movies on ordinary SD cards but now with the latest High Definition video cameras needing much more space and you would need a pocket full of ordinary SD cards. SDHC now makes recording DVD quality home movies on SD cards a reality and HD home movies a possibility. The fast write speeds of the cards ensure that jerky, stuttering videos should be a thing of the past.
As mentioned earlier, SDHC is a new standard using a new file system. This may mean greater capacities and speeds but it is no use to devices that were built to the old standard. The new file system means that older devices and card readers that only recognise the old file system simply won't be able to read the disks. Only the very latest digital cameras, camcorders and even card readers that recognise both the new and the old standard will be able to make use of SDHC cards, for everything else they are pretty much useless. As consumers we are getting used to this kind of thing, with VHS, DVD, Blu-Ray and HD-DVD. The 'latest technology' is now superseded with increasing regularity. But this doesn't make it any less annoying, particularly if you have just spent several hundred pounds on a new digital camera or camcorder that is not SDHC compatible. In that case you'll just have to wait to be able to make use of the bigger capacity cards, either that or buy a new device.
Most devices are incompatible with SDHC cards, basically anything that first came on sale more than three months ago isn't likely to be able to make use of SDHC cards. Some of the recent devices that are compatible are:
- The HTC Touch smartphone
- The Palm Treo 680
- The Nokia N800 Tablet
- Nokia N95 mobile phone
- Nikon D40
- Nikon D80
- Pentax K100D
- Pentax K110D
- Pentax K10D digital SLRs
- Crucial 12 in 1 USB Card Reader
It is likely that all new devices that use SD cards will also support the new standard of SDHC as well as the old.
The faster SDHC cards also have another potential use for Windows Vista users, Windows ReadyBoost. Assuming you have a card reader that is SDHC compatible you can use your SDHC card for caching Windows files, rather than storing them on the hard disk. This will give read speeds around 100 times faster than a traditional hard drive. Particularly useful if you are running Vista with the bare minimum amount of RAM.
While you may be forgiven for thinking that the latest crop of 4GB and 8GB cards could be used to give your device a much needed storage boost, this unfortunately isn't the case. The new standard of SDHC cards are only really useful to those who are purchasing the latest SD enabled devices. For those of us who are still using devices that only read ordinary SD cards, we'll just have to stick to our 1GB and 2GB cards until we buy another SD enabled gadget (which in all fairness probably won't be too far into the future), and make sure that it is SDHC enabled.