Everything You Need to Know About SD Cards

George Finlayson
May 31, 2017

Since the digital revolution in the world of photography, memory cards (in particular SD Cards) have become one of the most important parts of a photographer’s arsenal. Just as a film photographer can’t shoot without their film, a digital or mobile photographer can’t capture photos without a memory card.

Many brands have experimented in various types of memory cards before, but these days, most camera brands have adopted the SD (Secure Digital) card as their memory card of choice.

Now you might be wondering, “If everyone uses SD cards nowadays and there’s no danger of incompatibility, what else do I have to know about them?”

Remember: not all SD cards are created equal.

If you want to be a serious photographer, you have to know how to choose the SD card that fits your shooting requirements and budget best.

3 Types of SD cards

Today, there are 3 main types of SD cards: SD, SDHC, and SDXC

SD cards are the the oldest and slowest of the three, and they usually have a very small storage capacity (4 GB or less). They’re practically obsolete for photography purposes, but as they are the forerunners of the other two types, it’s still important to know about them.

SDHC cards are faster than SD cards and have storage capacities of over 4 GB to 32 GB. They also come in microSDHC format which are usually used for mobile phones. However, you can also use microSDHC cards for cameras if you use an adapter.

SDXC cards are the newest and fastest of the three. While it’s still okay to use SDHC cards, it’s better to get SDXC cards if you can afford them. SDXC cards have capacities greater than 32 GB, so they allow you to store more photos without the need to change memory cards on the go.

SD cards according to speed

Now that you know about the 3 main types of SD cards, it’s time to learn about SD card speeds.

Card manufacturers usually classify their cards into 4 speeds or “classes.” These are Class 2, Class 4, Class 6, and Class 10. The lowest number, Class 2, means the slowest read and write speed, while Class 10 signifies the fastest read and write speed. With the large size of photographs these days, it’s best to not choose a card slower than a Class 10.

Another speed classification is the UHS or Ultra High Speed. A Class 10 card is classified as a UHS I card, while faster cards are classified as UHS II or UHS III cards. UHS III cards are significantly pricier, so if budget is a concern for you, stick to Class 10 or UHS I cards. These cards are good enough to suit the read and write speed requirements of many photographers.

Tips on choosing an SD Card

  1. Choose the fastest card that fits your budget

Card speed is extremely important in photography. When you miss a very important shot because your card is still saving your last image, you’ll definitely regret not getting a faster card. The price of a memory card increases the faster it is, but it’s definitely a worthy investment.

As a rule of thumb, don’t purchase anything slower than a Class 10.

  1. Invest in reputable brands

In the case of SD cards, build quality is very important. It’s better to spend a little more and get well-known, trusted SD cards like SanDisk, Samsung and Lexar than risk getting subpar or unreliable SD cards to save a couple of bucks. Always buy from a trusted seller and never try to grab a bargain on places such as eBay; many of these will be cleverly disguised fakes that have slower read/write speeds.

  1. Always get a backup

While getting your super-fast, high-capacity SD card, don’t forget to allot a bit of your budget for a backup. Speed is also an important factor here, but you can give a bit of leeway to storage capacity, since it will just be your spare. For instance, you can get a Class 10 128 GB card as your primary storage and get a 64 GB or even 32 GB backup just to make sure that you’ll always have extra space. This will save you money as well since buying a separate 128 GB + 64 GB card setup will likely be cheaper than getting a single 256 GB card.

Now that you know the basics of SD cards, it’s time to shop for the perfect one for your DSLR, mirrorless camera, or action camera ‘ and start shooting!

About the Author

George Finlayson

George Finlayson is an educator and professional writer with a BA in Creative Writing. He was born in London, England but currently resides in Shanghai, China. He has recently developed a great interest in photography and has begun a new venture into writing about photography and videography for beginners, and related topics. With so many technical details in digital photography, George likes to keep things simple so that everyone can understand and feel a part of the ever-growing global photography community.

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