Many DSLR cameras use SD cards for storage.
The Nikon D3000 uses an SD (Secure Digital) or SDHC (Secure Digital High Capacity) memory card to store photos. The SD format was developed by the SD Association, which created the standards and specifications for the card. The association does not sell or produce SD cards, but promotes the consistent standard amongst different manufacturers, according to the SD Association's website. SD and SDHC cards are used by many different camera manufacturers including Canon, Nikon and Pentax.
Physical Characteristics
Both SD cards and SDHC cards have the same measurements. Each card measures 24mm wide, 32mm tall and 2.1mm thick, according to the SD Association's website. Both cards also weigh approximately 2g.
Storage Space
SD cards have a maximum capacity of 2GB, according to the SD Association. SDHC cards have between 4GB and 32GB capacity, the association states. These cards are generally used with digital cameras, such as the Nikon D3000, because of their higher performance and capacity.
Transfer Rates
SD and SDHC cards are separated in to Speed Classes. Each speed class has a number which corresponds to the minimum transfer speed of the card. The speed classes are 2, 4, 6 and 10. Thus, a class 2 has a minimum transfer rate of 2MB per second. The cards are listed by their minimum rate because certain devices require certain speeds to function properly. Thus, a device that is designed for Class 4 rates may not perform as well using a Class 2 card. The Nikon D3000 does not require a high speed card but increased transfer rates will mean faster downloading of files to a computer.
File system
Most SD cards use a FAT16 file system, while SDHC cards use FAT32. The FAT16 limits the volume of storage to 2GB, while FAT32 supports up to 32GB. FAT32 uses storage space more efficient than FAT16, according to Microsoft's Technet.
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