SD ( Secure Digital ) cards are now the most common form of removable storage media for all portable devices: tablets, cameras, camcorders, cell phones, smartphones and laptops. Various types of memories are available, of different sizes, capacities and speeds; in these cases it is quite easy to make a mistake.
To avoid unpleasant situations, to avoid throwing money on cards with low memory capacity, low speed or unreadable and to buy the right SD memory card for your purpose, it is important to understand the differences between the SD card models, which they are not all the same even with the same size.
Although it is not possible to indicate exactly what to buy for each type of device here, we see the general information to be prepared when going to buy a new SD card .
READ ALSO: Choose the best MicroSD for Android smartphones
SD memory card features
When buying an SD card we have to consider four main factors to consider:
- Speed class
- Bus speed
- Capacity
- Card size
Class
For SD cards there are several classes that can be purchased: class 4, class 6 or class 10 . This number simply allows to know the minimum writing speed of the card . The card number indicates the MB per second that the card can write on itself at least.
For example, a Class 2 SD card writes at 2 MB / s. In addition to these classes, UHS classes (class U1 and class U3) and video classes (from V6 to V90) are also available, which identify the fastest SD cards, dedicated to shooting and shooting professionals to make videos and to save photos. in very high definition in fractions of a second. One class does not necessarily exclude the other: a class 10 is also U1 and V10, while the fastest ones now available on the market are the U3 / V30, the V60 and the V90 .
2)
Bus speed
In addition to the writing speed of the single card, we will also have to take into consideration the speed with which the data come and go; that's why we talk about bus speed (i.e. the speed of metal contacts in exchanging data). This speed can be classified on the SD cards by means of a Roman symbol saved in a corner of the same; Normal classes (without Roman symbols), class I (first Roman numeral) and II (second Roman numeral) are currently available. To obtain the best results in terms of transfer speed we will have to adopt only the SD cards that have a Roman numeral (I or II), so as to be sure of making the most of the writing and reading speed.
Obviously also the device in which we are going to insert the SD card must have the same compatibility, otherwise it will not be exploited adequately.
SD memory capacity
The capacity of the SD card is the most obvious value in a shop window or mall. To avoid unnecessarily spending money on an SD card that is too small or too large, we need to determine more or less what we need for our electronic device. Keep in mind that there are currently three main types of SD cards with different capacities :
The types of MicroSD cards that are on the market are as follows:
- SDSC or Secure Digital Standard Capacity, with a memory capacity from 128 MB to 2 GB and FAT file system that is not compatible with the latest smartphones;
- SDHC or Secure Digital High Capacity have a memory capacity ranging from 4 GB to 32 GB, uses the FAT file system and is compatible with practically any modern device;
- SDXC or Secure Digital Extended Capacity have a memory capacity of 64 GB to 2 TB and use the exFAT16 file system; compatible with a large number of modern devices.
Considering that the digital cameras on the market today start from 13 megapixels and above and the smartphone cameras start from 10 megapixels, we make the choice of the card based on the number of photos that we can save on it: a 2GB SD card can hold about 380 photos saved in JPEG format, but not 100 if taken in RAW format. After inserting the memory card into the camera, take a picture and then check the data on the screen to see how many images the card can hold based on the shooting mode (JPEG, RAW, TIFF)
In this table, an estimate of how many Jpeg images can contain memory cards of various sizes, taking photos with different cameras.
In the case of smartphones we will also have to take into account the use of the SD memory card as a space where music files, video files and data files of some apps can be saved (such as for example the maps of the navigation apps) so better be foresight and focus on models from 64 GB up .
Card size
Speaking of SD cards in size, there are actually several models :
- Standard format (32mm x 24mm)
- MiniSD format (31.5mm x 20mm)
- MicroSD format (11mm x 15mm)
Each device should indicate what type of card it wants in the specifications, so that it is never wrong.
Smartphones always use microSD while cameras generally use the Standard format or at most the miniSD format (although SD adapters are increasingly popular to accommodate smaller formats without problems even on the largest slots).
SD and MicroSD cards to buy today
Referring to the Amazon store and in light of what is written in this post we can recommend buying one of these SD cards, taking into account that the most reliable manufacturers (brands) of memory cards are Samsung, Sandisk, Fuji, Lexa, Delkin, Viking and Kingston.
MicroSD
- Kingston SD : microSD format, 64 GB, class 10, U1, class I (€ 15)
- Samsung EVO Plus : microSD format, 64 GB, U3, class I (€ 12)
- Toshiba microSDXC : microSD format, 64 GB, U3, class I (11 €)
- SanDisk Extreme : microSD format, 128 GB, U3, class I, V30 (€ 40)
- Delkin SDXC : microSD format, 64 GB, U3, class II, V60 (€ 70)
SD card
- SanDisk Ultra : SD format, 64 GB, class 10, U1, class I (€ 21)
- Komputerbay SDXC : SD format, 128 GB, class 10, U1, class I (€ 18)
- Lexar Professional SDXC : SD format, 64 GB, class 10, U1, class I (€ 27)
- Delkin SDXC : SD format, 64 GB, U3, class II, V60 (€ 50)
- Integral SDXC : SD format, 64 GB, class II, V90 (€ 86)
6) Conclusions
For digital cameras and reflex cameras it is advisable to concentrate above all on memory space, therefore on 64 or 128 GB models.
For digital video cameras we consider class U1 and class I cards for videos with resolution up to Full HD (1920 x 1080).
For videos in 4K or high framerates we recommend focusing only on SD cards (of any type) with class U3, class II and class V60 or V90, so as to have the right writing speed when recording videos at these resolutions. For smartphones, a very high speed is not usually required, but let's make sure that the minimum is always an SD card with class 10, U1 and class I to be comfortable in any scenario.
We can also read the following guides on the subject:
- Guide to optimize memory cards and memory SD cards for cameras and mobile phones
- Programs for recovering deleted files and photos from memory cards and USB sticks
