How to Buy Memory Cards

This is a top line memory card from a proven maker.  Note that the amount of info on the face may not actually tell you want you want to know, such as sustained write speed

This is a top line memory card from a proven maker. Note that the amount of info on the face may not actually tell you want you want to know, such as sustained write speed

A reader asked me to go over this topic. So here we go.

There are lots of misconceptions about memory cards, and frankly, a lot of no longer useful information marked all over them. Let’s see if we can make some sense of this.

Card Type

As it stands at time of writing, there are five common memory card types. We see SD, CF, CompactFlash, XQD and MicroSD. Are there others? You bet, but they exist only for older cameras and typically are very hard to find in stores, making them hard to buy.

The only thing that you care about when it comes to card type is if it fits your camera physically. I say only thing, because if your camera is very old, it may have an internal bus that limits it to maximum card size, typically 2GB or less. If that’s the case, good luck to you because those things are like hen’s teeth, meaning that they do exist but are very hard to find.

Card Labeling

Cards are covered in labels and acronyms. There are only three things that you care about.

  1. Does the card fit and work in my camera?

  2. How much storage does the card have?

  3. What is the sustained write speed of the card?

On a good day, you will find answers to the first two questions, getting the answer to the third is more difficult.

Card Class

This is mostly marketing hyperbole. You can ignore it because of the amount of BS involved and the lack of it really mattering at all. Anyone who makes a case for a specific card class is trying to sell you something and figures you don’t have a clue. Walk away. In fact these card class ratings are just so much crap, I won’t even waste the time explaining them all to you because they are so out of date as to be irrelevant

UDMA or UHS Number

Higher is better. That’s it.

Read Speed

Typically measured in megabytes per second, this is one of two parameters that makers play very fast and loose with. Unless otherwise documented, conclude that this is the maximum burst read speed and that it is unattainable for any length of time. If the read speed is rated really really high, it’s BS. Read speed only matters when you are copying information from a card to something else, like a computer hard drive. It doesn’t have much impact at all on the speed with which the JPEG preview gets to the camera LCD.

Write Speed

Typically measured in megabytes per second, this is the other parameter that makers play fast and loose with. Unless otherwise documented, conclude that this is the maximum burst write speed and that it is unattainable for any length of time. The more important question to ask is what the maximum write speed of your camera is. Putting a fast card in a camera with a slower internal bus adds no value. Putting a slow card in a camera with a faster internal bus is a big waste of the money that you spent on the camera. Always try to match or slightly exceed the internal bus speed of your camera. Having trouble finding out what the internal bus speed of your camera is? You aren’t alone. Manufacturers do a pretty shit job of documenting this, but a tip is to check the maximum video bandwidth that you can record in. If your camera is rated at 100Mbps maximum bandwidth for video, that’s the bandwidth on the card slot so try to match that with the card that you use.

Life Cycle

Memory cards use flash memory. It’s pretty darn good, but is not the same as the flash memory used in Solid State Drives. Flash memory can go bad over time and there’s no “I’m starting to die” notification. Based on MTBF (mean time before failure) numerics, I recommend replacing memory cards every three years or so. This does not mean that they die after three years, only that the probability of random death is closer to 50%. The deal with cards is that newer cards might be better built, will certainly have more current flash memory, and will likely deliver a lot more capacity than the card that you have for about the same money as you paid three years ago. Card prices used to hold and double capacity every year, but that has slowed down a lot. Nonetheless, storage is cheap. Why risk that one time shot on an old card. Certainly if you get a new camera, get new cards with it. To do otherwise is really silly, unless the cards you have are less than three months old and max out the camera internal bandwidth.

What Brand to Buy

There are limited sources for high end flash memory out there. These makers will sell off the memory that doesn’t make their cut to others. Card makers will also use different internal components, with the better cards using better quality components and the lesser cards being a lot less concerned about your images. You actually do get what you pay for. I used to recommend only Sandisk and Lexar cards, but Lexar went away when Micron Technologies shut it down, so anything you see with a Lexar label is very old stock. These days, I would stick with Sandisk and Sony, and if your camera uses the excellent XQD cards, you are stuck with Sony. If that’s the case buy the higher end XQD cards and not the entry level ones. Unfortunately with Sony being the only game in town, you are getting hosed on price. Welcome to Sonyland!

Any other brand that you see, other than perhaps Toshiba is using someone else’s memory and that means its not top tier memory. Store brand cards are built in Asia from the cheapest possible components with the lowest quality control in order to maintain the highest profit margins. Margin on a Sandisk card might be 30% to the retailer. Margin on the house brand card is probably close to 85% even at the reduced sell price. These cards are NO bargain and my recommendation is to avoid them like you would a rabid bat. But hey, it’s your camera and your images, do whatever makes you happy. Personally, I wouldn’t use them ever.

You may have had great success with Jimmy’sOwnSDCard. If so, that’s nice but please don’t waste either of our time by telling me. The same is true if you have had a bad experience with a no name card. It’s possible to have a bad card happen with a top line vendor, but those vendors also provide lifetime warranties for their best cards and respond very well. The only downside is that most camera stores no longer handle lifetime warranty across the counter, not because they cannot, but because they do not want to incur the human cost of collecting and prepping the warranty claims. That’s a business decision on their part.

Do you have an idea for an article, tutorial, video or podcast? Do you have an imaging question unrelated to this article? Send me an email directly at or post in the comments.  When you email your questions on any imaging topic, I will try to respond within a day.

If you shop with B&H Photo Video, please consider doing so through the link on as this helps support my efforts and has no negative impact whatsoever on your shopping experience. 

If you find the podcast, videos or articles of value, consider clicking the Donation tab in the sidebar of the website and buy me a coffee. Your donation goes to help me keep things going. 

I'm Ross Chevalier, thanks for reading, watching and listening and until next time, peace.