With many manufacturers and multiple symbols on SD cards, here is which memory card a beginner should buy!
SD or CF Card?
The first part of your choice is likely made for you as it depends on which type of slot your camera has. The majority of cameras have a slot for the physically smaller sized SD cards (pictured to the left) rather than the larger CF cards. Some of the “professional” cameras only offer the CF card slots, but most of the newer bodies either offer both types of slots or only SD. You can look it up in the online specs or the owner's manual to see which your camera has, but it is pretty easy to tell just by looking at it. If the slot for your memory card is about the size of your thumbnail it is SD. If it is 2 or 3 times wider than that, you have CF.
Since most of the cameras support SD cards, that is where the beginner should start things off (you likely have no choice). Specifically a “full” sized SD card, not a mini or micro sized SD card. You can use adapters to make those physically smaller SD cards work in your full sized SD card slot, but simpler is always better with electronics and if you can avoid an adapter you should. Of course if your camera only has a CF slot then you have to get a CF card. The good news is CF cards have been around longer and generally have been faster, so you nearly can't go wrong with them for your camera (except for that 20 year old one that has been gathering dust in your office, don't use it).
SD Card Symbols
You have likely purchased and used SD cards before you got your “nice” camera. Many point-and-shoot cameras use them, along with smartphones, GPS devices, and many other types of electronics. So you have probably seen all of the symbols these things can be littered with. The chart above from www.sdcard.org does a good job of outlining what the symbols mean and what kind of applications they were intended for. The numbers in what looks like a big “C” (for class) give you a good indication of the write speed of the card. The numbers inside of what looks like a “U” (for UHS) indicate that the cards work with a UHS bus, which means they are faster than those without the symbol.
Symbols to Look For
OK, so that's great, but which one does a beginner need for their new camera? I recommend one with at least class 10 and UHS-I to make sure your card can do a good job of keeping up with your camera. Your camera has something called a buffer that your shots get written to as you push the shutter button. The buffer is a relatively small amount of really fast memory inside your camera. It is used so that you can take between 3 and 10 shots a second (depending on your camera) as you press and hold down the shutter button. The SD card is much slower than the buffer memory, so once you use up all the buffer memory your camera won't take another picture until you let it write out what is in buffer to your card. The faster your card, the less time you will wait for your camera to “catch up.”
However, it isn't necessarily true that if you got a class 10, UHS-II card that you will see a lot of difference on all cameras. That depends on your card slot, and what technology it supports. If you have an older camera like the Canon T3i or the Nikon D3000, then you won't see much difference with a faster card because the SD slot in them isn't fast enough to fully utilize it.
You can probably get away with a class 4 card if you really need to for some reason (maybe you have one already), but things will go better with a faster card. If you are buying a new card there isn't much price difference anymore, in fact looking at Amazon as of the date of this article it looks like there are more options and cheaper prices on class 10 cards than class 4. If your are going to do any video then class 4 will not be enough. In fact, I have had trouble with a class 10 card (wasn't UHS-I) when shooting video where the video would stop recording. If you want to shoot video I recommend looking for a class 10 UHS-I card that has 45MB/s written on it too. Personally, right now I only buy class 10 UHS-I cards rated at 90+MB/s.
SD / SDHC / SDXC?
What about the difference between SD, SDHC, and SDXC? You can breathe a little easier, this isn't nearly as complicated as the other symbols on the card. SD allows for the card storage size to be up to 2GB. 2GB to 32GB is SDHC. 32GB to 2TB is SDXC. This again will be very dependent on the camera you have. Older camera models may not be able to use an SDXC card with over 32GB of storage. Check your owner's manual to see which type of card it supports. If your camera doesn't support SDXC, then you are limited to SDHC cards with a maximum storage size of 32GB.
How Many GB?
As a long time IT professional, just have to take a second here and laugh that the title of this section includes GB. Seriously, GB. Kind of crazy. Anyway, you have lot's of options in storage size from 2GB up to 2TB. Yeah, TB. Again, crazy. So, bigger is always better, right? I am hoping I can convince you that in this case it may not be. For stills I think the optimal size of a memory card is 16GB, unless you have the Nikon D810 which has such big RAW files you will want at least 32GB. 32GB for video, maybe 64GB (make sure your camera can use an SDXC card) if you are really going to shoot a lot.
I can hear you as you read this article. “Wait,” you are thinking, “if I can get a 128GB class 10 UHS-I SDXC card why wouldn't I?” Because, while SD cards are pretty tough (some have been readable after spending days to weeks in the ocean), they do and will fail. SD is type of flash memory that has a limited number of writes. It absolutely will not last forever. If you are out shooting you could easily put an entire day's work on a single 128GB SD card, something that is super convenient. But what if at the end of the day something terrible happens and the card gets ruined or lost? Your entire day is gone. Eventually you may end up doing a paid shoot, can you think of anything worse than going home after a day or two of shooting to find you can't read the only card you used?
Trust me here. Get a couple of smaller cards that you will deliberately switch out as you do your shooting. Use one in the morning, and another in the evening. Use one at this location and a another at that location. There are usually natural breaks in your shooting where you can switch them out. That said, there is one caution to be aware of here, if you write to the card until it is filled up you are significantly more likely to end up with an unreadable card (a situation where when you stick it in the computer it can't be read). Doesn't mean it absolutely will result in an unreadable card, but it is more likely, and therefore should be avoided. The card also gets slower as it gets full. So spend some time learning how it is you can figure out how many more pictures you can take and switch it out as you get down to 10 or 20 or so (if not earlier).
If you are going to follow my advice you will get a couple of 16GB class 10 UHS-I cards. But Sony, SanDisk, PNY, Kingston, Transcend, and others make SD cards – which one should you get? I mostly don't think it matters. That is why they have the symbols on them. In order to put those symbols on their cards they have to have meet some minimum requirements and should mean that they are all about the same.
That said, I have personally seen cards with the same symbols perform differently. In fact, I have spent some time with the cards I have purchased in the past couple of years and tested them on the computer to see what their real read/write speeds are. They are not all equal. My test size it too small to share and have it mean anything, I did it just so that I knew which cards I wanted to use for video, but I will share that my experience hasn't been as good with Transcend branded SD cards for video (just fine for stills). Oh, and don't even bother trying to use an Amazon Basics SD card. They don't have any of these symbols on them, and that is because they are junk.
On the podcast Jim has mentioned a couple of times something special Lexar offers with their professional class cards. If your card goes “unreadable” in some way, you can send it in and they will use their tools to do all they can in the way of restoring the data that was on the card and send you the data plus a new card. Pretty incredible service there. Add that to the very high quality of the Lexar branded SD cards and that may just make the slightly higher cost very worthwhile.
One final feature that is not all that common in SD cards is WiFi. Yes, WiFi. If you buy a WiFi enabled card that is compatible with your camera body (check with the SD card manufacturer to make sure it will work in your camera because they don't work in all of them), when you use it a little bubble of WiFi will be around your camera and you can connect your phone or tablet to it. Then you can use an app provided by the manufacturer (another thing to check out before you buy to make sure the app works on your phone/tablet) and see the shots put on the SD card by your camera as soon as you click that shutter. Very cool feature that is built into some more modern cameras (Sony and Panasonic are killing it here), but an SD card with WiFi is a way to add it to many bodies that do not.
I haven't ever used a WiFi enabled SD card. I worry they will be very slow and that creating that WiFi bubble will kill the battery life of the camera very quickly. I have heard from many photographers that they work very well and love the ability to shoot using a much more capable camera than their phone/tablet yet still be able to post the images to social media instantly. I would imagine this could also be a big selling point with clients where they could see the pictures on a tablet as you take them – if you are brave enough for that.
Anyway, for a beginner, I recommend staying away from SD cards with WiFi built in for a while for the simple reason that it isn't worth the extra cost to get the feature.
SD cards go on sale. A lot. Given that your SD cards are going to die someday, as a hobbyist with little budget to spend on equipment, I buy a fast 16 or 32GB card every time I see them on sale. Usually for something like $10-$15. This is another good reason to get a few “smaller” sized SD cards because I have yet to see anything higher than 64GB cards in the sale, and 32GB is almost always there. This has allowed me to get fast cards at 50% off and now I have enough of them I know when I go to do a shoot that I won't have a problem of which SD card to use. In fact, I have enough I can leave my photos on them for a while as sort of a temporary offline backup in case I do something terribly stupid on the computer. So, keep this in mind as you see sales happening at the various online retailers and pick up one or two because I think you can never have enough of them myself.