Memory cards are all over the map — a wide range of formats, sizes, and speeds. Some cards throw a bunch of numbers at you, while others may only list their capacity. Confusing doesn’t begin to describe this, and if you’ve been looking for a new card for your camera or other device, chances are you’ve experienced this. We can help sort things out.
There is no universal memory card to fit all devices — not yet, anyway. Smaller devices like smartphones necessitate the use of smaller cards, like the fingernail-sized MicroSD, while professional cameras can use larger ones that offer greater capacities and speeds. There isn’t really a trick here, you just need to know what kind of card your device requires.
Here’s an overview of the common types:
CompactFlash (CF) – And oldie but goody, CF cards were the mainstay of digital cameras for years. The format has reached its peak, however, with no room left for improvements in speed. Some high-end cameras still take CF cards today (the larger size appeals to the working professional), but the format has otherwise all but been replaced by physically smaller and faster alternatives.
Secure Digital (SD) – Roughly the size of a postage stamp, the SD Card is a mainstay of the camera industry, spanning entry-level to professional models. Capacities and speeds have surpassed those of CF; SanDisk recently introduced a one terabyte SD card. If you own a DSLR or mirrorless camera (or are looking to buy one) there’s a good chance that it takes an SD card.
MicroSD – Essentially a miniaturized version of SD, MicroSD is found primarily in action cameras, phones, and other devices where physical space is limited. Maximum capacity currently stands at 256 gigabytes and speeds can be up to 275MB per second, making the format a serious contender for professional applications. Its small size and flimsy design can make it awkward to work with it, however.
While it’s possible to use MicroSD cards in SD devices with an adapter, we recommend sticking to the full SD when possible. Save those MicroSD cards for devices that require the format.
CFast – Do you shoot an ARRI cinema camera or a Canon 1D X Mark II? If the answer is “no,” then you don’t even need to know of the existence of CFast, a high-capacity, high-performance format for professional devices.
What you should know, though, is that while CFast is roughly the same size as CF, the two formats are not compatible. If you have an older CF camera, don’t inadvertently buy a CFast card thinking it’s what you need. We agree, the nomenclature is confusing, but it is what it is.
XQD – Similar to CFast, XQD is a high-end format for professional applications. With a theoretical maximum bandwidth of a gigabyte per second, it has the most potential of any current removable storage format. Few cameras use it today, with Nikon’s D500 being the closest thing to a consumer-level product that offers it.
Universal Flash Storage (UFS) – The current frontier of flash memory, UFS is being spearheaded by Samsung who introduced the first UFS card this summer — despite the fact that there are no devices currently using it. With a form factor similar to MicroSD, UFS offers blazing performance improvements and may become the new standard for mobile devices and action cameras in the future. But as of this writing, you have no reason to go out and buy one.
Stick to Name Brands
Buying a name brand memory card can cost more, but along with the name comes a trustworthy company, a good warranty, a generous exchange policy, and a reputation for stability — something that’s much more critical than it sounds.
There are only three major producers of flash memory: Samsung, Micron (which owns Lexar), and Western Digital (which owns SanDisk). For photo applications, Lexar and SanDisk are the two largest names and we wouldn’t hesitate to recommend either. This doesn’t mean other brands won’t deliver a quality product, but they tend to be more hit or miss on average.
Need for Speed
Not all Flash Memory cards are created equal, even when they may be the same format and capacity. When it comes to how a card performs in your device, speed is the most important attribute.
High-end memory cards will clearly display their speed ratings. These will either look something like 633X, 1000X, or 2000X, or they will list the actual megabytes per second. (For reference, 1000x is 150MB/s.) While a fast card is not necessarily a requirement for every device, it’s useful info. And if the manufacturer isn’t up front about the speed rating, we advise not buying the card.
The other thing to consider is that memory cards have two different speed ratings, one for the read speed (or transfer speed) and one for the write speed. The read speed is almost always the faster of the two and will be the number most prominently displayed, while write speed is often only shown on the back of the packaging.
The faster the read speed, the faster you can offload content to your computer (provided you have a USB 3 card reader or other interface that can keep up with the card). But write speed is the more important number when it comes to the performance of your device. Especially in high-resolution cameras and for 4K video, a fast write speed ensures you won’t encounter any slow downs while shooting.
SD and MicroSD also bear a “speed class.” Your device’s manual (you know, that paper book you threw away?) will indicate the recommend speed class, which will probably be either Class 10, UHS U1, or UHS U3. U3 cards are often recommended for 4K video shooting, while the slower U1 and Class 10 are fine for casual use.
While a faster card is almost always better, there are specific cases in which this is not true. For always-on devices like dash cams or home security systems, a slower card is just fine and may even be more reliable, but make sure it’s still rated for your device’s minimum requirements. Lexar, for example, makes a line of High-Endurance cards for this specific purpose.
Capacity is much easier to understand than speed, so this is an easy one to grasp. The higher the capacity, the more photographs, video, or other data you can save to the card.
In general, bigger is better — but just as you may not needed the fastest card, you almost certainly don’t need the largest. Card capacities have grown exponentially, and while professional photographers shooting thousands of photos a day may opt for the highest-capacity card they can find, most people are probably fine with something in the 32GB to 64GB range.
A common school of thought suggests it is better to buy two smaller cards than one larger one. In the event your device is stolen, you accidentally reformat a card, or you drop your camera into the pool, this could minimize the amount of data you lose. Many higher-end cameras also include dual card slots, which allows for automatic back-up in-camera, so having a second card is never a bad idea.
If you know what you need, then you’ll likely find it for less on Amazon than in a brick-and-mortar store. When a retailer buys memory from a supplier, it gets a discount for buying in bulk. The more cards a store orders, the cheaper that memory becomes. Quite simply, physical stores just can’t compete, and you can find name brand memory online for sometimes hundreds of dollars less than the manufacturer’s MSRP.
If you want more help or you’re not sure about your device’s particular memory card requirements, however, you’ll find added value by visiting a reputable camera store — if you’re fortunate enough to have one in your area.
While the urge to pick up that cheap memory card in the checkout line at Target might be hard to resist, avoid impulse buys. Take some time to read your manual and do some research online, and you’ll find that making an informed and economical purchase is quite easy and can net you a much better product.
The memory card that works best is the one you won’t notice at all; it’s the slow or unreliable ones that you’ll notice, and they can cause quite a headache.
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