SDHC memory card confusion...

[NTB]

Maybe I'm just goofy, but I swear I've seen single cards - or at least cards of the same 'type', if not the same capacity - rated under *both* of these systems, with considerably different results. For instance:

late last year I purchased a 2GB PNY-branded card from best buy rated at 133x . Using the old CD-ROM standard of 150K / second, that would be almost 20MB / second transfer. However, in recent weeks I've seen a 4GB version of this same card (and maybe newer 2GB cards as well - I'll check when I go by BB today) labeled as 'Class 6'. If I understand the 'class' system correctly, this would indicate a comparitavely meager 6MB /second transfer rate. I've also seen similar things with Sandisk's higher-end cards: Ultra-II, Extreme-III, etc. What's going on here?

If anybody's curious, I've brought this up because I'm looking to do a couple of things: a) I want to get a 2nd card for a friend to use in her Pentax K100D-Super, and I'm also looking for a larger & faster card to use in my own MP3 player. I have a 'standard' purple Sandisk card in there now, and while it works fine, it's dirt slow - the card is indexed every time the player is turned on, and even at less than 1/2 full, it takes quite a while. I'm hoping a faster card will alleviate that somewhat.

EDIT: Here's one example, though not quite as bad as the one mentioned above: a 2GB Sandisk Ultra-II card marked as both 66x, or roughly 10MB / second, and Class 4 - 4MB / second. wtf?

EDIT #2: and yes, I am aware that only 4GB cards and larger are considered SDHC. Sorry 'bout that.

Nathan

 

[fuzzybabybunny]

There are two types of SD memory cards:

SD: this is your older version of SD and its capacity tops out at 4GB. Speed ratings are in "x"
SDHC: this is your new version of SD and capacity can be greater than 4GB. It is not compatible with regular SD. Speed ratings are in "class"

You have to make sure your device can take SDHC. If it doesn't specifically say that it's SDHC compatible, it can't take SDHC and you have to get a regular SD card. If your device is SDHC compatible, chances are it is also compatible with regular SD.

And yeah, the speeds of SDHC are not yet up to the speeds of regular SD, although it's not often that a 133x SD card will get to 20MB/s... in my experience with my 2GB 150x Transcend, it does an average of 10MB/s.

 

[NTB]

Originally posted by: fuzzybabybunny
There are two types of SD memory cards:

SD: this is your older version of SD and its capacity tops out at 4GB. Speed ratings are in "x"
SDHC: this is your new version of SD and capacity can be greater than 4GB. It is not compatible with regular SD. Speed ratings are in "class"

You have to make sure your device can take SDHC. If it doesn't specifically say that it's SDHC compatible, it can't take SDHC and you have to get a regular SD card. If your device is SDHC compatible, chances are it is also compatible with regular SD.

And yeah, the speeds of SDHC are not yet up to the speeds of regular SD, although it's not often that a 133x SD card will get to 20MB/s... in my experience with my 2GB 150x Transcend, it does an average of 10MB/s.

I realize that some of the numbers are probably...*ahem*...stretched for marketing purposes; I was just wondering why the difference is so large.

Also, after doing a little more reading, it seems that the 'class x' ratings are SD Association-certified minimums for write-speeds only, and class 6, or 6MB / second, is as high as they currently go.

As for compatibility: My friend's camera is a K100D Super, one of the main features of which was supposed to be SDHC compatibility, so 4GB+ cards should work. My MP3 player is the same way: an Insignia Pilot, which is SDHC certified, and currently working with a 4GB Sandisk card. As stated before though, it's one of their 'standard' cards, and seems to be dirt slow.

Nathan

 

[fuzzybabybunny]

Originally posted by: NTB

Originally posted by: fuzzybabybunny
There are two types of SD memory cards:

SD: this is your older version of SD and its capacity tops out at 4GB. Speed ratings are in "x"
SDHC: this is your new version of SD and capacity can be greater than 4GB. It is not compatible with regular SD. Speed ratings are in "class"

You have to make sure your device can take SDHC. If it doesn't specifically say that it's SDHC compatible, it can't take SDHC and you have to get a regular SD card. If your device is SDHC compatible, chances are it is also compatible with regular SD.

And yeah, the speeds of SDHC are not yet up to the speeds of regular SD, although it's not often that a 133x SD card will get to 20MB/s... in my experience with my 2GB 150x Transcend, it does an average of 10MB/s.

I realize that some of the numbers are probably...*ahem*...stretched for marketing purposes; I was just wondering why the difference is so large.

Also, after doing a little more reading, it seems that the 'class x' ratings are SD Association-certified minimums for write-speeds only, and class 6, or 6MB / second, is as high as they currently go.

As for compatibility: My friend's camera is a K100D Super, one of the main features of which was supposed to be SDHC compatibility, so 4GB+ cards should work. My MP3 player is the same way: an Insignia Pilot, which is SDHC certified, and currently working with a 4GB Sandisk card. As stated before though, it's one of their 'standard' cards, and seems to be dirt slow.

Nathan

I don't know specifically why the differences are so large between reality and rating. The specific card reader and the size of the files can both affect speeds. So the "x" rating is probably a max that few ever attain, and the "class" ratings are minimums, although I've certainly had my Class 4 SDHC go below this due to craptastic card readers (ie. using my PDA phone as a card reader). I would just try to get the fastest you can afford, especially for high capacity cards.