SD

secure-digital-card

I am positive that at some point in your lifetime you have either owned or seen the Secure Digital (SD) memory card. These cards are everywhere and I am sure that in the past decade I have gone through 20 different brands and sizes. When it comes to storing your digital goodies, SD Cards are the go to memory option.

SD memory cards are typically used in different digital devices such as cameras, camcorders, mp3 players, GPS units among others. Despite the popularity, you will find that SDHC cards have overtaken them as they are able to provide more storage space. SD cards are the old format and they are slowly going the way of the dinosaur.

What is the Secure Digital (SD) Memory Card?

Secure Digital memory cards are some of the most popular storage devices in the world. You will find that these minute memory cards in used in a variety of digital devices from cameras, camcorders, mp3 players etc.

The typical standard Secure Digital card capacities range from 4 MB up to 4 GB. New SD formats have been introduced, which has seen memory sizes increasing. SDHC cards when released, where able to store up to 32 GB of data. In 2009 it was announced that a new format Secure Digital eXtended Capacity (SDXC) would be released.  This SDXC format would allow for the possibility of 2 TB memory cards.

SD cards are very small and they are around the size of a stamp. Its dimensions are 24 mm (W) × 32.0 mm (H) × 2.1 mm (D) and it weighs 2 grams. SD cards have the ability to encrypt data and the cards also have write protection.

What is the Difference Between SD, SDHC & SDXC?

With so many different types of memory cards available, it can really be confusing trying to know what memory card will work with what device. It is even more confusing when it comes to SD, SDHC and SDXC memory cards as they all are the same shape and at times, each card can be used in varying devices.

Once you know the significant differences between the cards, there really won’t be much confusion.

The differences between the 3 Cards

Secure Digital (SD Cards) – SD cards are only available in sizes from 8MB – 2GB. These are older memory cards and as such their storage capacity is nothing to write home about. Newer devices that use SDHC and SDXC memory cards can use SD cards as they are backward compatible.

Secure Digital High Capacity (SDHC) – SDHC cards come in sizes from 4GB – 32GB. These cards are some of the most popular on the market these days. These cards can only be used in any device that takes SDHC & SDXC.  SDHC devices can use SD but not SDXC cards.

 

Secure Digital eXtended Capacity (SDXC) – SDXC cards are the new kids on the block and they come in sizes from 48GB – 2TB. You can only use these cards in devices that take SDXC. SDXC devices will be able to take SD & SDHC cards as they are backward compatible.

 

The Different SD Memory Card Sizes

Because Secure Digital (SD) Memory Cards is the older format, you will find that there are a variety of sizes available. You will typically find SD cards in capacities such as 16 MB, 32 MB, 64 MB (older formats), 128 MB, 256 MB.512 MB,1 G &, 2 GB. As I mentioned, these cards are over the hill and you will often find that people will still use the 512MB, 1GB and 2GB sizes. The good thing with these particular memory cards is that you will be able to purchase them for cheap.

Secure Digital Card Speeds

With Secure Digital memory cards there are different speeds available. The speeds of the cards determine how fast the data is written. Some devices such as digital cameras often require high speed cards. This is the same with the newer video cameras that use flash memory. They need fast cards as they will be writing huge amounts of data to these cards.

Some SD card manufacturers will use different ways to identify the speed ratings of their cards.

Below is a table that lists the common speed ratings. Also examined is the minimum transfer speeds.

Rating

Speed (MB/s)

SD Class

  6x

 0.9

 n/a

  10x

 1.5

 n/a

  13x

 2.0

 2

  26x

 4.0

 4

 32x

 4.8

 4

 40x

 6.0

 6

 66x

10.0

 6

100x

15.0

 6

133x

20.0

 6

150x

22.5

 6

200x

30.0

 6

266x

40.0

 6

300x

45.0

 6

SD Speed Class Ratings

Both SD Cards and SDHC Cards have Class Ratings that are determined by the speed of the card. These ratings are able to identify the minimum write speeds.

  • Class 2: 2 MB/s – 13x
  • Class 4: 4 MB/s – 26x
  • Class 6: 6 MB/s – 40x

Storage Capacity of SDHC Memory Cards

Sometimes people cannot get an idea as to how much data their SD Card will be able to hold. This is the reason why I enjoy doing up tables, as you will be able to see for yourself, exactly how much pictures and video each specific memory card will be able to hold.

 **When it comes to numbers in the table, you should be aware that the cards will be able to hold more or less data; it really depends on different factors such as the type of camera used, resolution of the picture or megapixel of the camera.

 

 

256 MB

512 MB

1GB

2GB

SD Video (640×480)

6.25 min

12.5 min

25 min

50 min

HD Video (720p 10 Mbps)

3 min

5.6 min

11.25 min

22.5 min

HD Video (720p 15 Mbps)

1.5 min

3.min

6.25 min

12.5 min

HD Video (1080p 9 Mbps)

3.75 min

7.5 min

15 min

30 min

HD Video (1080p 13 Mbps)

2 min

5 min

10 min

20 min

Pictures (JPEG 10 Megapixels)

55

110

220

440

Pictures (JPEG 14 Megapixels)

32

65

131

262

Pictures (Raw 10 Megapixels)

16

33

66

132

Pictures (RAW 14 Megapixels)

9

18

36

73

SD Card Compatibility

Because the SD Card format is older technology, there is always some cause for concern regarding its use in more modern devices. With the SDHC and newer SDXC memory cards, you will find that there is a good possibility that the SD Card might not work in them.

  • SD Cards – SD cards can be used in devices that take SD, SDHC and SDXC.
  • SDHC Cards – SDHC cards can only be used in devices that take SDHC and SDXC.
  • SDXC Cards – SDXC cards can only be used in SDXC devices.