4 Most Important Factors for Selecting a DSLR Memory Card

Memory cards are a necessary piece of equipment for any digital photographer. Most cameras do not come with built in storage, so you need some way to record the images that our camera sensors capture. Luckily, navigating the world of memory cards is not that difficult and it’s fairly easy to figure out what you need for the type of photography you do.

Here are the four specs you need to keep in mind when selecting a memory card.

A variety of SanDisk cards


First, you need to find out what kind of card your camera uses. The two important formats are Secure Digital (SD) and Compact Flash (CF). Most cameras use a version of SD cards, either plain old SD, SDHC or SDXC.

SDHC stands for High Capacity—meaning between 2 and 32 Gigabytes. The SDXC allows an even higher capacity in the same size card—up to 2 Terabytes. Compact Flash cards are much bigger in physical size and, these days, are typically only used in higher-end cameras and video cameras. Like the name implies, these cards use flash memory to record data. You can get cards from 2GB up to 128GB. In years past, Compact Flash cards were faster and could hold higher capacities than SD. However, in 2014, the difference between the two is difficult to see.

Memory size on the card

When I say the size of the card, I’m referring to the amount of data it can hold. When choosing a capacity, consider how large the files you need to store are. Are you shooting RAW files or JPEG files? Are you working with an 8 Megapixel camera or a 50 megapixel camera? Depending on the capacity of the card you could hold a few dozen images or a few thousand images. If I’m photographing something important, I prefer to use several smaller cards. On the outside chance one of the cards becomes corrupt, I won’t lose ALL of my images. 8GB cards hold about 300 images for my camera. Every 300 or so images I’ll change cards.


Cards are assigned a class based on their write speeds, either 2, 4, 6 or 10. Class 10 cards are able to write at least 10 MB/sec, while Class 6 cards can write at least 6 MB/sec. In addition to the class, memory cards will have a speed rating. This is the maximum write speed. Some are 30 MB/sec and some are 45 MB/sec, etc. The faster your card can write data, the more photos you can take in a row, and the higher definition of video you can continuously record. If you are a casual shooter with a relatively low resolution camera, you will be good with a Class 4. If you take photos often, ever use burst mode, or shoot HD video, you should use a Class 6. If you shoot a lot of HD video or need speed with a high resolution camera, you should use a Class 10.


I would recommend brand name cards as the way to go when choosing a memory card. You can certainly find great deals on off-brand cards, but you run the risk of them being cheaply made or not carrying a warranty. When it comes to accurately preserving your photos until they get to your computer, it’s not worth the risk of using a sketchy memory card. Unfortunately, even the best manufacturers have cards that fail. Pick a brand with a good reputation for quality and you minimize your risk.

For even more tips on digital photography, check out the new Craftsy class The Basics of Digital Photography, where your learn all the essential techniques for mastering your DSLR!

What cards do you recommend? Have you ever had a card fail? What cards do you not recommend?


Ann-Marie Mair

I had a card fail at exactly the wrong time. It was an 4Gb SanDisk CF card in my Canon EOS 10D (at the time) back in 2008. We were on vacation in Yellowstone National Park. I had been waiting and desperately hoping to see a wolf. We slowed down behind a park ranger who was going really slowly and we saw what looked like a black German Shepherd dog running along the road in front of and next to him. I snapped one shot and the CF card froze up. My one and only wolf in the wild ever and the damned CF card froze. The shots of the tiny black dot in the distance in the following three images were perfectly fine. It was just that one shot when he was right next to our car that I never got. I was gutted! This has been the only time, so far anyway, that a CF card has failed. I now have a Canon EOS 6D that uses SD cards. I have a SanDisk 64Gb Extreme PRO 95MB/s speed class 10. I LOVE it. At mid-size RAW and jpg images, I get approximately 2700 shots on this card. And can take some pretty excellent HD videos that I do at my kids choir functions at school. SanDisk is my favourite by far.


I highly recommend at least 2 cards, and personally carry 5 or 6 at any given time.You should also recommend backing the photos up on a regular basis, due to the fact that the cards could fail. I cringe whenever a customer tells me they use the memory card for long term storage, and just go get a new card when the first one is full. I guess working in a tourist area, I have heard too many lost photos stories from failed or lost cards.


I just bought one of the new SD cards with wifi capability – there are a few out there, but I bought the Eye-fi brand, class 10. So far I’m really happy with it. I don’t find it any slower at all, and uploading using the wifi is intuitive and quick. I’d recommend giving it a try.

John Doe

This article was completely useless and just webpage filler swill.

William Hughes

I presently use SONY SD, HC I. , Class 10, 40MB/sec.
I have been very fortunate to never have had a card fail.
I am just an enthusiast , but a serious one, so I would hate to loose any photos.

Andy Whitehurst

I use smaller capacity and change regularly, all your eggs in one basket is asking for trouble. That said I’ve only ever had one card fail and that was because I sat down on a rock with it in my back pocket!

Markas Easter

I have 2 SDHC Lexar memory cards, and to tell you the honest truth, I cannot really see any great significant difference between a 8gb at 6x speed and a 16gb at 4x speed.

I use a Fujifilm finepix S4000 point and shoot digital camera, which has 14 megapixels with 30x zoom wide angle lense, which is enough of a camera for me!

As I work 2 jobs (one of them is a casual job, where I have to work 7 days a week “rain,hail or shine”) and study 2 courses, so I don’t really get as much time as I would like to, as photography is a passion and a hobby for me!


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