A card SDHC (acronym for Secure Digital High-Capacity) is a flash memory device that can store between 1 and 64 gigabytes (GB) of data. It's really small in size, about the size of a postage stamp. These cards are a type of removable memory that can be used in many digital devices, the most common being digital photography and video cameras, computers and mobile phones. There are other SD cards but not all types are supported by all devices.
SDHC cards were developed by Matsushita (Panasonic Corp.) and released in January 2001. They normally use the FAT32 file system although they can be formatted in different file systems.
Applications
SDHC cards are used for store and transfer information from one compatible device to another. Many digital devices have slots where these cards are inserted. For example, digital cameras, music players, computers, tablets or mobile phones.
Perhaps the most popular use of SDHC cards is for recording and transporting media files (videos, audio and images) from cameras or other recording devices to computers where they can be further enhanced or stored for longer term use. The operation of SDHC cards is similar to any other removable memory device, users can copy and paste files directly to the card and extract information from it.
Classification
SDHC cards were an improvement on the original SD cards (from 1999). The new SDHCs addressed the growing need for greater storage capacity as high-definition video and high-resolution digital photography were increasingly used. SDHC cards also offered higher data transfer speeds. This speed is measured in megabytes per second or DTS (Data Transfer Speed). According to the DTS, SDHC cards are classified into 4 types or classes:
- Class 2: Minimum DTS of 2MB/s
- Class 4: Minimum DTS of 4 MB/s
- Class 6: Minimum DTS of 6 MB/s
- Class 10: Minimum DTS of 10 MB/s
The final speed of data transfer depends on the card reader. If a class 10 SDHC card is used in a reader that supports a maximum of 2 MB/s, it will never exceed 2 MB/s. Also note that this rating sets the minimum speed, not the maximum, so higher performance can be achieved depending on the card and reader.
Choose the right card class and capacity
High class cards are useful for those who are going to use them for record hd video or save many high resolution images. If you choose a lower class for this purpose, you may find that the HD video is left with a lower quality or that it is not even recorded at all. Most experts recommend class 6 SDHC cards for HD work. The speed of these cards is sufficient for most recordings and they are cheaper than class 10 cards.
A 32GB SDHC card can store 4,161 compressed 22-mepapixel photos, or 416 uncompressed 22-megapixel photos. In video, a 32GB card could store up to 60 videos at 30fps (frames per second) of two hours each. It is advisable to check that the recording devices can work with these capacities, some cheap ones cannot read cards of this capacity.
Compatible devices
Most devices that can read external memory are designed to read specific types of cards and other storage methods. Newer devices are usually made capable of reading external memory with current standards as well as older technologies (although not always), but most older devices are not capable of reading later developed storage methods. In other words, devices with SDHC card readers can usually read SD cards as well, but devices with SD card readers usually won't be able to work with SDHC cards. Some manufacturers offer software updates to allow older devices to work with the new cards or make external readers that can be connected to the device, for example through a USB port.
If SDHC cards are not specified as a supported storage method in the instruction manual of a device with a card reader, it means that only SD cards are supported. There are more modern memory cards, SDXC cards; most devices that accept SDXC cards can also read SDHC cards but not vice versa, those that can read SDHC cannot always read SDXC cards if it is not specified in the characteristics of the device.