There are scores of SD cards of all shapes, sizes, and speeds available, so picking the right one for each device can be slightly confusing.
When it comes to flash memory cards, there are three aspects you need to consider: physical format, size, and speed. We’ll explore the distinctions below.
The first thing to consider when getting a memory card is where you’re going to use it. Different cameras, camcorders, and smart phones use different sizes of card, and while you can start with the smallest and use adapters to work your way up, it’s generally best to use the card size intended for the device.
The standard SD card is the largest and has been in use the longest, measuring 32 by 24 by 2.1 mm (HWD), weighing 2 grams, and showing the signature cut-corner profile SD cards are known for. Most digital cameras you can buy today use standard-size SD cards. Even though they’re the largest SD card, they’re still very small, and are dwarfed by the Compact Flash cards used by professional photographers in high-end digital cameras, like the $5,000 Canon 1D Mark IV. However, the cards can get even smaller.
MiniSD cards, the least frequently used format these days, measure 21.5 by 20 by 1.4 mm (HWD) and weigh just a gram, making them just over a third the volume and taking up just over half the area of a full-size SD card. Instead of cut corners, miniSD cards have a tapered corner to help you orient the card when putting it in a slot. This design aspect follows with the smallest of the SD cards, the microSD card.
MicroSD cards, which are used in most cell phones and smart phones, are downright Lilliputian, measuring 15 by 11 by 1 mm (HWD) and weighing only half a gram. With a total volume of 165 mm3, you could fit nine microSD cards inside a single SD card (though realistically, with the slight lip found on the end of microSD cards, you could probably only squeeze in six).
Generally, microSD cards cost slightly more than SD cards of the same size and speed class, but that, along with the physical size are the only effective differences.
SD cards offer different storage capacities, and that amount of space determines the card’s size classification. Odds are the microSD card in your smart phone isn’t a microSD card. It’s a microSDHC card, or Micro Secure Digital High Capacity. “Standard” SD cards max out at 2GB capacity, based on their classification and the controller used by SD-only devices. Most SD cards you’ll find today are technically SDHC, with capacities between 4GB and 32GB. The largest class is SDXC, or Secure Digital Extended Capacity, can range from 64GB to 2TB. (Currently, no cards actually get anywhere near 2TB; the largest capacity available is 128GB.)
While larger is better, you need to make sure your device can use the larger card. The SD/SDHC/SDXC classification isn’t just for cards, but for devices as well. Older digital cameras can only read SD cards, making SDHC cards useless. Similarly, cameras that aren’t SDXC-compatible won’t accept 64GB cards. Most current devices are SDHC compatible, but double-check your older devices before getting SDHC cards, and check the specs on your newer gear before getting SDXC cards.
SD cards are also available in various speeds. If you’re using a point-and-shoot digital camera or a standard-definition pocket camcorder, speed class won’t matter much. If you’re shooting high-resolution RAW photos with a digital SLR, however, you need a quick card to take more than two or three shots at a time. SD cards are generally described by their Speed Class, ranging from Class 2 (slowest) to Class 10 (fastest). There’s also a separate, even faster category called UHS Class 1 (for Ultra High Speed), but most current devices can’t use them.
Generally, if you want to shoot HD video or if you plan on taking a lot of high-resolution photos in quick succession (or use a digital SLR’s RAW image file format), buy a Class 10 card. If you’re planning to just take snapshots or occasionally show videos, Class 4 or Class 6 will do. Since even smart phones can record HD video these days, Class 2 cards aren’t the best choice. They’re simply too slow to record HD video, so you’re limiting your device’s features. The price difference between Class 4, Class 6, and Class 10 cards can vary, but not vastly. Always check your device’s documentation for support information before you commit to a memory card.
In closing, 4 smart tips are provided:
Back it up: You should always remember to save your images to multiple locations such as your hard disk, an online service or other external devices.
Format your card: Before use, always format your card in the camera. This function deletes data and creates new folders to prevent database errors while shooting.
Data Recovery: If you accidentally delete an important image, stop shooting and use Card Data Recovery to recover the image.
Protect your investment: If you have a single card, use the supplied plastic holder to prevent impact damage when storing it. If you have multiple cards, use a case to organize them better so you’ll know which cards are used or unused.