Memory cards: how to choose and use the right storage device for your camera

Memory cards for cameras: how to choose and use the right storage device

In this jargon-free guide we’ll explain everything you need to know about choosing and using all the different types of memory cards for cameras.

Memory cards for cameras: how to choose and use the right storage device

It’s easy to take your camera’s memory card for granted. However, you only have to go into a camera shop to realise that memory cards come in a bewildering array of sizes, formats and speeds.

It’s easy to work out what memory card format you need – unless you shoot with the Nikon D4s, it’s either Compact Flash or SD.

As far as capacity is concerned, your camera’s LCD display will tell you how many images you can save on your current memory card.

If you shoot raw files, which we usually recommend, you’ll need more storage space, but a 16 gigabyte card should be enough, although individual needs will vary.

SEE MORE: Best memory cards for cameras – 9 top options tested and rated

Understanding memory card formats

Compact Flash is the oldest memory card format still in use. They’ve disappeared from most beginner and enthusiast DSLRs, but are still going strong in the top-end pro models.

They come in two types, and Type I cards fit all cameras. Type II cards are fatter, and are no longer made or supported.

Most Type II ‘cards’ were a clever but fragile miniature hard disk ‘MicroDrive’ design, but solid state Type I cards have long since outstripped the capacity of Type II cards.

SD cards are the most common memory cards for cameras, and are used across most camera ranges range except for in top-end pro models.

Although all SD memory cards are physically the same, there are three types. SD cards are the oldest and will work in any camera with an SD card slot.

SDHC cards are newer but only work in SDHC-compatible cameras (see the list overleaf). SDXC cards are newer still and need an SDXC-compatible camera.

Finally, XQD is a brand-new format used in the Nikon D4s (and D4) that we mentioned earlier. The cards offer potentially huge capacities and ultra-fast data transfer speeds, but it’s early days, and the future of the format is by no means guaranteed.

SEE MORE: A layman’s guide to memory cards – common questions answered

Which memory cards should you use for your camera?

You can find more information about your specific camera’s requirements in your manual, but here we’ve listed the different types of memory cards for cameras as a rough guide.

Don’t worry if your camera’s memory card size is different than what your manual suggests.

Your manual will list sizes available at the time the camera was released, but higher-capacity memory cards for cameras released later should work too. Your manual only lists memory cards which have been tested by your manufacturer.

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Memory cards for cameras: how to choose and use the right storage deviceCommon memory cards for cameras

Compact Flash Type I cards are 3.5mm thick and are still used today. Newer cards and cameras use the faster UDMA interface for higher transfer speeds.

Compact Flash cards come in many capacities – in 2013, SanDisk launched a 256GB card.

Compact Flash Type II cards were 5mm thick and are no longer supported by most modern DSLRs.

Most Type II CF cards were ‘MicroDrives’ – tiny spinning hard disk drives in a CF-sized case.

SD cards are the oldest and least powerful SD card type, with a maximum capacity of 2Gb. You can still use SD cards in modern digital cameras, but their low capacity limits their usefulness.

As a result, standard SD cards are rarely seen now – SDHC is the new norm.

SDHC cards are a faster, higher-capacity replacement for the SD format. Card sizes go up to 32Gb, with card speeds up to Class 10 and UHS-I.

You can only use SDHC cards in cameras that support them – and most current DSLRs support SDHC.

SDXC cards offer higher capacities even than SDHC, starting at 64GB and going up to a theoretical maximum of 2TB. SDXC cards typically come with a UHS-1 speed rating.

You can only use SDXC cards in cameras that support them. This includes cameras from 2010 on.

The new XQD format is designed for high capacities and high data transfer speeds. So far, the professional-standard Nikon D4 and D4s are the only cameras to use this new card format.

It offers capacities in excess of 2Tb and potential transfer speeds of 125-500GB per second.

SEE MORE: Best photo accessories – transform your images for less than £100!

How much speed do you need from your memory card?

How much speed do you need from your memory card?

Continuous shooting: maximum possible speed
A faster memory card won’t let your camera shoot at a faster rate. The frame rate is fixed by the camera hardware.

But the camera is saving images faster than it can write them to the memory card, so it saves them temporarily to an internal memory ‘buffer’ while it’s shooting.

The faster your camera’s memory card, the longer it takes for this buffer to fill up, and the quicker it can empty the buffer when it’s full.

So a faster memory card in your camera will let you shoot a longer burst, and it will reduce the delay before the camera is ready to start shooting again.

The maximum speed rating of the memory card is a pretty good guide to how well it’s going to do this.

SEE MORE: Raw vs JPEG – how many pictures can you actually take with each format?

HD video: minimum sustained speed
When you shoot HD video, the camera has to write the data straight to the memory card in ‘real time’.

If the minimum ‘sustained’ speed falls below a certain level, you get dropped frames in your footage.

This is why SD/SDHC/SDXC memory cards now have a ‘Class’ rating and some CF cards have VPG 20 (20MB per second, fine for amateur use) and VPG 65 (65MB per second, for pros) logos.

A minimum sustained speed of 10MB per second is adequate for 1920 x 1080 full HD video, while 30MB per second is needed for the new 4K video standard.

HD video speed ratings – Minimum sustained speed

SD Class 10 – 10MB/s
SD U-1 – 10MB/s
SD U-3 -30MB/s
CF VPG 20 – 20MB/s
CF VPG 65 – 65MB/s

PAGE 1: Understanding memory card formats
PAGE 2: What the numbers on your memory card actually mean


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  • Michael Clark

    UHS-I (with a roman numeral “capitol i/one”) is not the same standard as U1 (with an arabic “one” inside the “U”). The former regards the bus speed/clock frequency with which the card communicates with the host device, which normally indicates a maximum *read* speed approaching the standard. UHS-I requires a bus speed of anywhere from 12.5 MB/sec (SDR12) to 104 MB/sec (SDR104). UHS-II requires a bus speed of either 156MB/sec ((FD156) or 312 MB/sec (HD312).

    The latter is a standard regarding the card’s minimum sustained *write* speed: U1 requires 10 MB/sec , U3 requires 30 MB/sec. This is the speed the card uses to actually write data to a sector of memory within the card, and is usually considerably slower than the card’s bus speed/clock frequency with which it is connected to the host device.