A Simple Guide To Memory Cards

I am not a gear guy. Let's get that straight right up front. I am a shooter. There is a difference. Gear guys know all about the technical side of cameras and everything that attaches to them. Shooters ask you to explain it in layman's terms, and then quickly figure out how to best use those capabilities. Whatever they are.

So the explanation you are going to get here is not from a technical side, but from a practical side. Ready? Here we go...

There are 2 main types of cards that we are using right now. CF and SD. There is a third type, but only one camera can use it, and that is an XQD card. We won't talk about that, because most of the memory card makers refuse to make it, and only one camera on the market uses it. So let's forget that one for now.

Here is what they look like:

This is an SD card

This is a CF card

First things first. Is one better than the other? Well that depends on how you look at it. For general purposes, no. One is not better than the other. However....

If you were to look closely an an SD card, You would see it has 9 pins. On a CF card, depending on the type, you get 50 to 68 pins. 

Let's pretend that data - images - were cars. And those pins were highways for those cars to travel on. It does not take a rocket scientist to figure out that you can get data onto a CF card quicker than an SD card because it has more roads for those little cars to travel. You can also, by the same token, get them off the card quicker when you plug them into the computer.

In general. Remember that we are not going to be all technical with this.

BUT... Unless you are shooting uncompressed RAW images in 15 shot bursts, it probably does not matter. Why? Because the camera has memory of it's own. Real fast memory. And those image, before they ever hit the memory card, are first written to the internal memory. That internal memory, which is way faster than the card, acts like a buffer. Images are temporarily stored there until they can be offloaded to the card.

Most cameras have a pretty large buffer. So if one card is slower than the other, no matter what type or how fast that card may be rated at, you never reach a place where the camera does not shoot. Unless, of course, you are shooting uncompressed RAW images in a big long burst. And most people do not do that. If you do, then you are shooting fast action sports. Even then, you are typically firing in 5 or 6 shots burst. Unless you are undisciplined and believe in the spray and pray mentality.

As you can tell from that wording, I don't.

Now if you are shooting fast action sports, then it makes sense to have the fastest stuff you can for those moments that do require 15 shot bursts in uncompressed RAW versus jpeg. It will happen for those people. But like I said, not much. But because it will, then be prepared. That means you want to shoot a 50 or 68 pin CF card in a camera that can handle that. Plus, that card needs to be rated to be fairly fast. We will get to speed in a minute.

Lets' first go back to SD cards and expand on those. In the SD world you have three main types. SDSC, SDHC, SDXC.

SDSC are standard cards. This is an older format for older cameras. SC stands for Standard Capacity.

SDHC are for newer cameras. Including most point and shoot cameras. HC stands for high capacity. You need to read your owner's manual to see what type yours requires.

SDXC are for newer upper end models. XC stands for Extended Capacity.

It is only important to know what your camera uses. If yours uses a SDXC - and most newer DSLR cameras do - then it is also backward compatible to the SC and HC models of memory cards as well. But the reverse is not true. Chances are, your camera uses XC versions as even most point and shoot cameras are using these now. But you should check to make sure.

Next to consider is speed. In speed, there are 2 things to consider. What is the burst rate, and what is the Class rating? Burst rate is how many megabytes per second it can transfer. Class rating is, what is the sustained megabytes per second the card can transfer. The class rating is important for those that record video on their camera.

Generally speaking, a class 10 rated card should be fast enough for most everyone. Class 10 is rated at 10 MBs or 10 megabytes per second. Though the burst rate will often be higher. So just do yourself a fvor and buy a class 10 card. Here is a great one for under $12.

Now let's talk about CF cards. We already explained that they are generally faster because there is more roads for cars to travel on. They are not rated in "classes", however. They have a "times" rating. So you will see this card, for example...

It is a 400X or 400 times card. How fast is that? Well considerably faster than a class 10 SD card. A 400X card will run you about $42 for the same size one above but can transfer data at sustained rate of 60MBs, or 60 megabyte per second. Now you know why there is a price difference. In addition, you will often find another acronym on many of those cards. UMDA. Ultra Direct Memory Access. Basically, it is how we can get even faster speeds. Most cards that are over 266X will be UMDA cards. In order to take advantage of those faster speeds, the camera must be compatible. Also, to off load the card at that faster rate, the card reader for you computer must be UMDA compatible as well.

Here is a great one to look at.

There is also something called type I and Type II cards. Most everything now-a-days is Type II, so that should no longer even be an issue worth talking about. But Type II cards are thicker. A type I can work in a type II slot, but not the other way around.

Now I copy and paste what I said about speed above: Unless you are shooting uncompressed RAW images in 15 shot bursts, it probably does not matter. Why? Because the camera has memory of it's own. Real fast memory. And those image, before they ever hit the memory card, are first written to the internal memory. That internal memory, which is way faster than the card, acts like a buffer. Images are temporarily stored there until they can be offloaded to the card.

Most cameras have a pretty large buffer. So if one card is slower than the other, no matter what type or how fast that card may be rated at, you never reach a place where the camera does not shoot. Unless, of course, you are shooting uncompressed RAW images in a big long burst. And most people do not do that. If you do, then you are shooting fast action sports. Even then, you are typically firing in 5 or 6 shots burst.

So botom line is any class 10 SD card and any UMDA or 266X or faster CF card will work plenty fast enough for most anything you will do. Unless you work for Reuters and get tasked to shoot the olympics and need blazing fast speed over long extended bursts.

FINALLY - DOES BRAND MATTER? Some will tell you yes. That they will only use brand X, or whatever. But the truth is, probably not. I have yet to find a brand that out performed ny other brand in name alone. Anybody that says they have, is probably not being very truthful with themselves. (Probably gonna pay for that remark...)

For final reference, here is a chart for you to bookmark.....

1000x = 150MB/s
 966x = 145MB/s
 933x = 140MB/s
 900x = 135MB/s
 866x = 130MB/s
 833x =  125MB/s
 800x = 120MB/s
 766x = 115MB/s
 733x = 110MB/s
 700x = 105MB/s
 666x = 100MB/s
 633x =  95MB/s
 600x =  90MB/s
 566x =  85MB/s
 533x =  80MB/s
 500x =  75MB/s
 466x =  70MB/s
 433x =  65MB/s
 400x =  60MB/s
 366x =  55MB/s
 333x =  50MB/s
 300x =  45MB/s
 266x =  40MB/s
 233x =  35MB/s
 200x =  30MB/s
 166x =  25MB/s
 150x =  22.5MB/s
 133x =  20MB/s
 100x =  15MB/s
  66x  = 10MB/s (SD speed class 10)
  40x  = 06MB/s (SD speed class 6)
  26x  =  04MB/s (SD speed class 4)
  13x  =  02MB/s (SD speed class 2)