June 2007 HelpLine

June 2007 HelpLine

• Insecure About SDHC
• A Reminder To Back Up


Insecure About SDHC

Q) I’m going on the trip of a lifetime in a few months and I was looking to stock up on memory cards so I don’t have to bring my laptop with me. With prices coming down and card sizes going up, I thought I’d have an easy decision. When I got to the store, I became confused. There used to be just one flavor of SD; now there’s SDHC. Should I try out the new cards?

Jose A.
Via the Internet

A) With some memory cards these days, capacity really doesn’t have an effect on which card to choose. I say “these days” because in the early days of digital cameras, some camera operating systems could only work with smaller memory cards. So not only were you concerned about the different types of memory cards, you also had to be a little wary of card capacities.

Digital photographers know a memory card can never have too much room. As manufacturers have increased capacity, they have had to modify some of the original card designs. Look at CompactFlash (CF), for example. Originally, there were Type I cards, but soon Type II cards came out. Electrically, CF Type I is equivalent to CF Type II, but the Type II card is a bit thicker. The thicker cards allowed for larger capacity at first, but these days, the extra thickness isn’t needed. Of course, it was fairly easy to tell if the Type II card would work in your camera: If it didn’t fit physically, it wouldn’t work.

SD or Secure Digital cards now have a new type that you mentioned in your question: SDHC. The HC stands for high capacity. In size and shape, the card is identical to the original SD card, but electrically, they’re not the same.

The consortium that tries to control all things SD is the SD Card Association. Formed in 2000 by SanDisk, Panasonic and Toshiba, it now has been joined by a long list of companies. The task of the association is to forge a rock-solid memory card standard to allow for interchange of media across many products.

The SD Card Association developed a new specification (SDA 2.00), which is the basis for the SDHC cards. This new design ups the potential capacity of cards to 32 GB (that capacity is still a ways off).

As for speed, instead of trying to mimic CD-ROM drive speed ratings like 4x, 8x, 16x (which seemed a little strange to me, but I didn’t have a better idea other than the raw data rate), SDHC cards now have a Class Speed Rating. This rating specifies a minimum sustained write speed. The three classes are simply known as Class 2, Class 4 and Class 6 and represent a minimum sustained write speed of 2 MBps, 4 MBps and 6 MBps, respectively. Of course, these are minimum speeds and manufacturers will continue to improve performance. While you’ll see the new class rating, you’ll also see a read/write speed specification that’s manufacturer-specific.

Okay, so now you know a little bit more about SDHC, and it has been all good news. Now for the bad news: SDHC cards aren’t backward-compatible with SD cards. It’s worth repeating: SDHC isn’t SD. Yes, physically they’re the same size and will fit into each other’s slots, but electrically, they’re not the same.

Here are the compatibility rules: 1) You can use an SD card in any SDHC slot. In other words, if you buy a camera that supports SDHC, you don’t need to throw away all of your old SD cards, as they will work just fine; 2) You can’t use an SDHC card in an SD slot.

There are some rare situations (almost not worth talking about, but I want to bring it up for you experimenters out there) where an SD device might be able to access an SDHC card, but it might only have access to part of the storage. This type of access isn’t even worth considering-with digital images, you need a consistent, reliable data memory system. So stick with SD cards for SD devices and SDHC or SD cards for SDHC devices.

If you’ve read this column over the years, you know how I’ve espoused the card reader as the reliable, must-have accessory for getting your images to your computer. The SD/SDHC compatibility issue extends to card readers, too. I know I might be a little redundant here, but I want to make the issue clear. If you’re heading down the SDHC path, you’ll need to purchase a new card reader, too. (Some manufacturers have deals that include a reader with an SDHC card purchase.)

So how do you know if your equipment supports SDHC? There’s an SDHC logo that you can look for. Obviously, you can check your manuals. You also can check the manufacturer’s website to see if it has SDHC-compatibility information or if it has a software upgrade that might add SDHC compatibility to your device. Memory card manufacturers’ websites also list compatible devices, though you’ll find the devices need to be fairly new. Remember that trying it out to see if an SDHC card works in the slot might not be the best test.

Don’t forget to consider all of the devices in your digital-imaging chain. I was talking with someone who had just bought a new camera and was all set to convert to SDHC cards. As I chatted with him about getting new cards, I realized that he does a fair amount of printing directly off his SD cards by inserting them into the SD slot built into his two-year-old printer. So while he had considered the camera and a new card reader, he hadn’t thought about his printer. If his printer isn’t SDHC-compatible and can’t be upgraded (or replaced), he’d have to stick to using SD cards in the printer.

Before I leave this topic, I want to bring up another issue with larger SD (not SDHC) cards. If you remember back to the first paragraph of this column (yes, I’ve been going on for a while about this), I mentioned that with some memory cards “capacity really doesn’t have an effect on which card to choose.” I put a lot of qualifiers into that sentence because there are two issues with some of the larger SD cards that people have come across:

• There are some problems with SD cards that are larger than 1 GB. Even though the spec allows for 2 GB SD cards, there are some devices—including some card readers and printers—that have difficulty with 2 GB cards (remember, I’m talking about SD).

• Some 4 GB SD cards aren’t built to the SDHC spec (you can tell because they don’t have the SDHC logo). These cards can cause problems in SD devices. If you put them in an SDHC device and then an SD device, you might end up with file corruption.

A Reminder To Back Up

No, this isn’t in response to a reader’s question, but I feel so strongly about backups that I want to keep reminding everyone to back up their data on a regular basis.

In my travels, I have the opportunity to meet with a lot of people from various electronics companies. Often, the conversation leads to requests for digital photography tips. The individuals aren’t pros, but they’re looking to improve their picture taking. While I’m happy to help, after the conversation goes on for a while, I can’t resist asking them one hard question: “When was the last time you backed up all of your images?”

Unfortunately, more times than not, the answer isn’t the right one. Please take the time to work out a regular system for backing up your computer. If a picture is worth a thousand words, one bad drive could make your computer speechless.

If you have questions, please send them to HelpLine, PCPhoto Magazine,
12121 Wilshire Blvd., Ste. 1200, Los Angeles, CA 90025 or

Leave a Comment