Digital Camera Memory Cards

Category: Hardware

I'm a little confused about all the different memory cards that are available for digital cameras and video cams. The memory card I bought for my digital camera is not recognized by my computer. Can you demystify this for me?

digital camera memory cards

Which Memory Card Should I Buy?

The first thing you should know about your camera's memory card is its format. There are about 20 different formats and subcategories of formats. The user manual or the vendor's Web site can tell you which format your camera supports. Be sure to buy only that format or a memory card will not fit into your camera. The most common digital camera memory card formats are:

  • CF (Compact Flash)
  • SD (Secure Digital)
  • SDHC (Secure Digital High Capacity)
  • xD (Extreme Digital)
  • MS (Memory Stick)
  • MMC (MultiMediaCard)
  • SM (Smart Media)

All but the cheapest digital cameras come with at least one memory card. Usually, it's enough for several days' worth of casual shooting. If you transfer photos from the camera to your hard drive or other storage media every couple of days, you don't need more memory. But sometimes you do need more memory, and better memory.

If you're going on a week-long trip, you don't want to run out of memory and you probably won't be able to empty your memory card frequently, if at all. If you're photographing a special event, you will snap a lot of photos and you don't want to run out of memory right before the groom kisses the bride. You need a memory card with lots of storage capacity. But how much capacity do you need?

How Much Storage Should a Memory Card Have?

It depends on how many photos you plan to take and how large each photo will be. Cameras generally let you specify low, medium, and high resolution for photos; the higher the resolution the bigger the photo file. Take a few photos at each of your camera's resolutions, upload to your computer, and note their file sizes. With a little math, you can estimate about how many photos your card can store.

Some cameras also incorporate file-compression technology; if that is enabled, a high-resolution photo will take up less space when stored in compressed (JPG) format than an uncompressed (RAW) photo. Here's an example of how many photos you'll be able to take with a 10-Megapixel camera and various sized memory cards:

FORMAT FILESIZE 512 MB Card 1 GB Card 2 GB Card 4 GB Card
RAW - Uncompressed 10.0 MB 51 photos 102 photos 204 photos 409 photos
JPG - Compressed 2.2 MB 232 photos 465 photos 930 photos 1861 photos

Memory Card Tradeoffs and Gotchas

Enabling compression slows down the storage process, though, so you have to wait longer to snap the next photo. That's no problem if you're photographing flowers but when snapping a tennis match or a fashion model, you want to snap-snap-snap very rapidly. Which brings us to high-speed memory cards.

Memory card write speed is the critical factor; that is, how many bytes of data are transferred from the camera's RAM to the card's memory per second. Like optical media, memory card speed is noted in multiples of a base speed, which is 150 kilobytes per second for memory cards. So a 10x memory card writes at 1500 kilobytes/second. The fastest memory cards currently available are 150x, and they cost a lot. Most consumers do just fine with around 40x.

If your memory card works fine in your camera, but your computer won't recognize the card, chances are it's one of the newer SDHC (Secure Digital High Capacity) cards. Most computers built before 2008 will not support SDHC cards, so you'll have to connect the camera to your computer via a USB cable. It may also be possible to do a firmware upgrade to enable your computer to read SDHC cards. Check with the computer vendor to see if such an upgrade is possible.

Here's another potential gotcha when dealing with digital cameras and memory cards. I have a friend who is "technology challenged," so to speak. She couldn't understand why her digital camera would store only four or five photos. Delving into its settings, I found she had it set to use only the camera's on-board RAM. After switching on the memory card, she had room for a couple of hundred high-resolution photos. So make sure your camera's settings will enable you to use whatever memory card you buy.

And yes, the brand name you buy does matter. Digital camera memory cards are essentially solid-state RAM chips, and quality control varies from manufacturer to manufacturer. Generally, well-known brands are more reliable than generic no-name memory cards.

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Most recent comments on "Digital Camera Memory Cards"

Posted by:

L B Geary
17 Dec 2009

Hi Bob. Would it be possible to use an SD card for back-up on a laptop? The WLAN on my school is terribly slow, and I can't carry an external HD with me. Do any back-up programs support this?

EDITOR'S NOTE: As long as your computer assigns a drive letter to the media card, it should work. A flash drive should work just as well, and is easier to carry.

Posted by:

18 Dec 2009

I work in photography and have bought several digital cameras and have yet to see any that come with a memory card. If one is included is done by the vendor to entice people to purchase the camera. In which case the card is usually a cheapie of poor quality. Most manufacturers leave it up to the consumer to purchase the card separately. Be careful purchasing the SDHC cards. Unless you are buying a high end camera it may not work. Check your manual before buying.

Posted by:

Dave Howell
18 Dec 2009

Hi Bob,

You forgot to mention that some cameras have an upper limit on what capacity card they will accept, e.g. my Panasonic FZ 30 will only take up to 2Gb cards.

Dave Howell

Posted by:

21 Dec 2009

You say that if your computer doesn't recognize your memory card, you have to use the camera to USB cord. Not so, you can buy a memory card to USB converter, a.k.a. card reader. I got mine for $4 but they usually are around $10. Advantage? Don't have to run down your battery on your camera.

Posted by:

Mmeory Card
25 Dec 2009

I read this blog and would leave my first comment. I don’t know what to say except NICE BLOG with a lot of information.


Posted by:

19 Jan 2010

Can you use the SDHC cards just for data? I don't have much use for a "photo only" card. Thanx

Posted by:

07 Apr 2011

I have some photographs in my memory card which i had clicked through my nikkon coolpix 3200.
Now when i tried transferring the data from the memory card to any laptop via data cable/ card reader or even directly, the laptop doesnt read it..
However when i open the pics in my digital camera it opens up and all pics show only in that digital camera..
Pls help.. i want to transfer my pics and need them desperately.. what is the way out.. have tried taking help from some local photographers & memory card sellers.. but even that did'nt help..

Posted by:

24 May 2011

Same problem as poster above (Mona) but my camera is a Fuji Fine Pix 4800Z. I've always just put the card into a card reader and connected to my PC to transfer pics but today the PC just shows an empty folder. Pics can still be viewed on the Camera. I tried another card and that one still works fine on both PC and camera so must be problem with the card ( just a bog standard 64mB SD card )
Lots of posters have similar problem, anyone have any ideas?

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