Test: Memory Cards – We Check the Speed on CF and SD Cards

Choosing the right memory card is not easy. There are a whole variety of memory cards to choose, where some are bigger, some cheaper, some more quickly. We have checked we both CF and SD cards, and how fast they really are in practice.

If you’re looking to buy a memory card for your camera, you’ve probably noticed that the jungle with memory card is big. Besides that there are many cards to choose from, after both the size and price, so it’s hard to know which card that keeps what it promises. In addition, it can be difficult to know exactly which card is best for your particular camera, because all of the cameras is fast and handles the cards differently.

Some cards are more expensive than others. One reason is that they have a larger storage space, but another reason is that they are faster. This is not to say that your camera can handle the higher speed, which means that you do not want to buy the most expensive – you may not be able to use the benefits of the card.

Different types

Two years ago, a new standard for SD cards that are referred to as UHS-1.The idea of this» Ultra High Speed was to meet the requirement for cameras that can shoot in full HD. UHS-1 card is in the camera, a theoretical maximum speed of 104 megabytes per second, which is more than what the camera produces when recording video in full HD.

SDHC Secure Digital card is where the name HC stands for High Capacity» «, which indicates that the memory card is over 4 GB and less than 32 GB. To manage a memory card that is so large, your camera cope with SDHC standard. Today, this is usually not a problem, but it’s good to know.

SDXC is, however, a little more modern standard, and means that the memory card is between 32 GB and up to 2 TB. Do you have a memory card of 32 GB or larger, so it is smart to check if your camera is SDXC compatible.

About the same is the arrangement of CF-cards. UDMA is a specification for measuring speed Pole of CF cards. We go back to 2006 so we can see that the UDMA-6 arrived, which meant a maximum transfer rate of 133 MB/sec. Today it is common with UDMA-7, meaning a theoretical transfer rate of 167 megabytes per second.

If the test

To test the memory card is not entirely obvious. There are various methods and test procedures, but also the different variables that play a role when it comes to the performance results to get out. The so-called bus speed is a source of different results on different devices, such as a computer or camera, since it is this bus that handles the data that flows through it from a particular device.

Another thing is that confuses any is that some manufacturers of memory card using the theoretical maximum speed that a value on how fast the card actually is. The problem we get then is that the theoretical speed is never going to come up, because it’s just theoretical and is under optimal conditions. The practical speed is what we measure in tests, and it will never reach an optimal performance due to certain factors, for example, the peripherals we use.

Important to know is that the speed we get with a specific memory card in the camera – or mostly – is different to the read and write speeds we get with a memory card reader in a computer.


We have tested 16 different types of memory card CF (Compact Flash) and Secure Digital (SD). Interesting to know is how the practical use of a memory card in a particular camera affect your photography, making the write speed is the most interesting. Another interesting test is to see how quickly you can transfer your pictures from the memory card to a computer, which enables us to measure reading speed for a computer.

To test this, we used a Canon Eos 5 d mark III, which have two slots, one for SD card and one for the CF card. By using the same camera for the two card types, we can also compare the cards against each other. What we don’t know here is how the camera’s data handling differs between the two card types.

Series of images in fastest mode

The camera was set up with the default setting of 1/1000 sec in manual mode with no lens attached. The image quality was set to raw form (L).The camera is capable of simultaneously contain 13 photos in its built-in buffer. The camera also was asked about to burst in fastest mode.Memory card was formatted in the camera.

After this we photographed with the memory card until the continuous speed of 6 frames per second, and the top screen on the camera showed» busy «, which occurs when a new image ends up on cue to be written to the buffer, and this does not have space for this new picture. Any image that almost could count to the series were counted in other words not in the test procedure above.

After the buffer has been filled were calculated also until the buffer has been emptied, which is the time between being unable to shoot due to filled buffer as described above, and that the diode for memory card went out. The test was repeated three times.

External card reader

To test the write and read speed against computer used an external card reader USB 3-type (Kingston USB3-FCR-HS3) connected to a Macbook Pro with OS X 10.8.3 from mid-2012 (Intel Core i7 USB3, 2.9 ghz, 8 GB 1600 MHZ DDR3, 750 GB, 5400 RPM).

126 photos in raw form on a total of 4 GB (4150 MB) copied over to your memory card (formatted in camera) with card reader to note the time it took (typing speed). The same image files then copied from the memory card to the computer to note this time (read speed). The test was repeated three times.


How to interpret the results depends on your type of photography.Unfortunately, it is difficult to accurately compare cards with other camera models then the bus speed is slightly different, although from this test can make a general comparison for how a card performs.

Canon Eos 5 d mark III can hold 13 pictures in its buffer, which in practice means that you can shoot in around two seconds before it is filled, if not skyfflats away from the buffer to the memory card. The buffer begins however, directly to shovel over the pictures you take to the memory card, so you can fit a few pictures to your series before you experience problems.

The slowest cards in this case just have time to receive and clear the buffer on the two images, because you can only shoot 15 shots before having speed problems. The fastest card, Transcend Ultimate 32 GB, however, let us photograph 17 images to, because the faster could receive and write data buffer gave it, with a total of 30 pictures before we had speed problems. Card write speed was measured up to the best.

CF before SD

Another thing we see is that the CF cards handle images for burst shooting faster. We look for example on SDHC card Sandisk Extreme Pro 16 GB that has a measured write speed of 55 megabytes per second, so give this card a series of 16 pictures in raw form before it becomes a problem. On the other hand, it gives the slower CF card Sandisk Extreme 32 GB a series of 19 images. Canon Eos 5 d mark III does so on – as well as several other DSLRs – to use a CF card before an SD card at serebildstagning.

For some, it is also important how fast it is possible to save all the images in the buffer, because this speed determines when you can start shooting a series again. Here was the CF card Transcend Ultimate 32 GB fastest with the shortest waiting time of 3 seconds before the buffer completely was empty. Also here we see the proof that CF cards do more work in the buffer against SD cards.

For example, we may take the CF card Kingston Ultimate 32 GB and compare against SD card PNY Pro Elite Plus 32 GB. Here we have measured both the write and read speed to the same, and the number of images in raw form in the series differs only with a picture card. Despite this, it takes almost double the time of SD card from PNY to empty the buffer completely. The worst of this was the two Wi-Fi-enabled SD cards from Toshiba and Sandisk.