How to choose your SD card

Photo cameras, smartphones, cameras, the list of devices using it is endless... An indispensable asset for photography, video and any kind of data storage, the memory card is a key part of almost all our electronic devices. Mainly used for removable storage, meaning to be able to save on a device, copy on another and then use these files, there exist many kinds, of many brands, with a lot of logos and standards as many as incomprehensible. We will try to decode them by rank to help you select the appropriate memory card for your needs. Note that not all acronyms are found on all cards... It would be too simple otherwise, wouldn't it? In addition, we will include some tips to avoid as many unpleasant surprises as possible and our recommendations.

Formats

• The CF card, for Compact Flash, is a bigger, more powerful card, although high-end SD cards are close to their level. Intended for very expensive reflex cameras, they are intended for a professional public and use very expensive equipment, for specific purposes. Sports photography, for example.
• The SD card, for Secure Digital, is smaller and fits most of our devices. It is the most widely used format. In the rest of this article, we will therefore focus strictly on SD cards.

Storage capacities

• HC for High Capacity. Indicates storage capacity from 4 to 32 GB. When replaced by XC, for eXtended Capacity, the card will be 64GB or larger. Used for outdated compatibility, we recommend to focus on the following acronym only, expressed in gigas. Should you be in doubt, you can check the compatibility of your old devices with the SDHC standard in the manual or in the technical specifications.
• 32 GB means 32 GigaByte. Indicates the maximum storage capacity in GB. This is the value to look at when making your capacity selection.

Any capacity is available, up to 512 GB, but the prices are exponential. Therefore, it is important to choose a capacity that suits your needs, else you risk losing money. With the remaining budget, it would be better to buy a second card to have several sets in case one of them fails. However, you should never fill them to their maximum capacity, to be on the safe side: every electronic device works with a small portion of free memory for its internal computations.

Some indicative tables below to help you choose the capacity you will need. These are average values, the numbers may vary slightly depending on your settings and the device you are shooting with. For photo shooting, it will also be crucial to choose whether you prefer to capture photos in JPG or RAW, as the storage required is dramatically different.

Pictures in JPG format

Table above: for photos taken in JPG format. The vertical line shows the capacity of the memory card, the horizontal line shows the resolution of the camera and the boxes show the number of photos which can be stored.

Pictures in RAW format

Table above: same as the previous one, but for photos in RAW format.

Video

Table above: for video. The vertical line shows the capacity of the memory card, the horizontal line shows the definition (or resolution) of the video and the boxes show the maximum recording time which can be stored.

Our recommendation: calculate your daily usage, add about 30% and take several cards of this capacity to change every day. This way, you will be comfortable every day and, in case of a problem, you will only lose one day's worth of images.

Classes

The symbol representing the class is the only one not blurred above: the 10 with an incomplete circle around it. It only takes even values, up to 10... Except for 8, for some unknown reason.

This is a category of minimum guaranteed writing and reading speed. The higher the number, the faster the card will be, for example :

• A class 4 will have a minimum theoretical speed of 4Mb/s for writing.
• A class 10 will have a minimum theoretical speed of 10Mb/s for writing.

In consideration of the current constraints, a class 10 is to be considered as a standard and will allow you a sufficient comfort for the classic activities of shooting. For video quality beyond 4k, then this standard is not enough and you will need to consider the next criteria.

Our recommendation: this is the most synthetic and important standard of all. Only consider class 10. And if you plan to shoot in 5k or 8k, you should definitely continue reading.

Speeds

These are all the symbols that are not blurred in the above image... And there are quite a few of them, but you will see that some are more interesting than others, starting with the first one listed.

Its symbol is the V with a number. V30 on the SanDisk card in the example. This is the minimum guaranteed video recording speed, created in response to the ever-increasing video resolutions on the market. Important therefore for those who want to shoot in high quality. Some examples:

• V6 and V10 are identical to classes 6 and 10 explained above: their minimum video recording speed is 6 and 10 MB/s respectively.
• V30: guaranteed minimum recording speed of 30MB/s. Ideal for full 4k recording comfort.
• The V60 and V90 should only be used for 8k recording. They represent a recording speed of 60 and 90 MB/s respectively.

Our recommendation: if you don't intend to use video or if you shoot in a quality lower than 4k, then this standard is useless to you. If you want to shoot in 4k, you may want to consider a V30, depending on your budget and settings. Beyond that, the V60 and V90 standards should only be considered if you plan to shoot in 8k.

The capacity, class and recording speed we have just seen are the three most important standards to understand. The following are explained as guidelines, but will not change the quality of your footage.

The next symbol is the one expressed in MB/s. 95MB/s on the Lexar card in our example. This is the maximum reading speed. Since reading speed is less important than writing speed, we are not interested in this standard. For example, when you transfer your pictures to the computer: it is comfortable to go fast, but you are not within 10 seconds. Also note that the read speed will always be higher than the write speed.

In the same context we sometimes have a multiplier: 633x on the Lexar card in our example above. This is a weird invention to show the reading speed in multiples of 0.15 MB/s. Redundant with the previous point, which was already not very interesting itself. And more complicated. To find out the maximum reading speed in MB/s, you have to multiply 0.15 with 633 (0.15 X 633 = 95 MB/s).

The U with a 3 in it on our example. U for UHS, which stands for Ultra High Speed. This is the transfer bus and this standard represents the read/write speed. Redundant with the minimum video recording speed.

• Class U1: 10 MB/s read/write.
• Class U2: 20 MB/s read/write.
• Class U3: 30 MB/s read/write.

The Roman numeral now. I (1) on our examples. Located below V30 on the SanDisk card and to the left of U3 for the Lexar. This is the generation of UHS, the bus interface: there are generations 1, 2 and 3. Logically, each is better than the last. The class and minimum video recording speed are still sufficient criteria for choosing your card and this one can be considered informative only.

A1 on our examples. It can take A1 or A2 values and represents the read/write speed for mobile applications. Useful to guarantee the performance of mobile applications on a smartphone using an SD card to store them for example. A2 is faster than A1.

Our recommendation for shooting lovers: for the speed, only consider the class and the minimum guaranteed recording speed.

Formatting

It is important to format your card before each new use. However, make sure you have backed up the contents previously. It is recommended to format on the device you are going to use. Because formatting does not only mean deleting everything, it also means that the folder tree and the system files are being processed at this time. This way you can avoid any potential disappointment that may be related to this.

Our SD cards

We have already sorted this out for you. In our shop, you will only find class 10 cards, so all you need to focus on is storage capacity and video recording speed.

Our SD cards

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