What is microsd. Which class of memory card is better to choose - an overview of SD formats. Other types of cards
Users are often interested in information about the microSDHC memory card: how it differs from microSD and microSDXC. Secure Digital Memory devices are widely used as additional storage options for portable devices such as tablet computers, mobile phones, digital cameras and GPS navigation devices. SD, SDHC, and SDXC drives are secure digital memory cards, but they have certain differences that you need to understand to ensure optimal performance in your portable devices.
If the user is interested in what is the difference between the types of flash drives, then he will be interested to know that the SD memory card is the first generation of Secure Digital, which was developed to improve the MMC (MultiMediaCard) standard. SD drives were created primarily to increase file storage space on mobile phones. The MMC standard is also used for data storage. It is similar to microSD, but is considered obsolete because it cannot provide a high enough information transfer speed.
For those interested in the difference between microSD and microSDHC memory cards, it will be useful to know that the storage size of a regular SD cannot exceed 2 GB. Typically, it has a standard physical size of 11mm x 15mm. The maximum read and write speed for such a drive is 25 Mbit/s. This is a very decent speed considering the small physical size of the device. This card is mainly used on mobile phones to store photos, videos and applications. SDHC and SDXC drives appeared later.
Second and third generation SD
SDHC
An SDHC (Secure Digital High Capacity) card differs from a regular microSD in its more capacious information storage, the size of which can range from 4 to 32 GB. It is also a secure digital device with a standard size of 11mm x 15mm. The difference between SD and SDHC is a higher data transfer rate (for Secure Digital High Capacity it can range from 50 Mbit/s to 150 Mbit/s).
SDHC memory cards are in many ways identical to SD drives, but there are significant differences. Older SD card devices are not compatible with SDHC because the latter uses the FAT32 file system instead of FAT12, FAT16 and FAT16B. The difference between microSD and microSDHC is that the latter uses a more convenient file system. However, some of the older gadgets can still use the Secure Digital High Capacity standard after a firmware update. Devices that are originally designed for SDHC should recognize regular SD without problems. Prices for such drives may vary depending on the amount of memory.
SDXC
An SDXC (Secure Digital eXtended Capacity) device can have a capacity from 32 GB to 2 TB and this is the main difference between SDHC and SDXC memory cards. Like other similar drives, the physical size is 11mm x 15mm. Data transfer speeds can vary from 50 to 312 Mbps. The speed potential of such a drive depends on the version of its design. Build 3.0 with UHS-1 (Ultra High Speed) bus can accelerate to 104 Mbps, and the more recent version 4.0 with UHS-2 reaches 312 Mbps. Prices for such drives can vary greatly depending on their capacity and speed. microSDHC and microSD devices are already considered obsolete standards in many countries. However, SD and SDHC memory cards are still popular.
Hi all! I think that many of you are interested in the question of which class of memory card is best to choose for a camera, video camera, tablet, mobile phone or any other digital device that uses an SD card to store information. Surely you know that there are several generations of SD cards with speed classification and memory capacity. So, each type of memory card has its own specification, which directly affects the scope of application and compatibility mode with a particular device.
Many consumers, when choosing a drive for their digital device, completely in vain ignore the classes of SD memory cards, taking into account only the type and large volume for storing information. IN Lately Manufacturers themselves clearly and clearly indicate in the specifications for the device what class of memory card is needed to work together with the device. However, some consumers still find it difficult to understand the types, classes, capacities and compatibility of SD drives. In this article I will try to talk as simply and in detail as possible about a digital memory card in SD format.
Let me start with the fact that the SD format has replaced the MMC portable flash memory card ( MultiMedia Card) with which they physically have the same size (32x24x2.1 mm), but technically have a different design. The format in question has its own controller and a special protected area from unauthorized access, as well as a manual switch to prevent unintentional erasure or overwriting of existing information. Keep in mind that accidental erasure protection is not activated by the SD card itself, but by the device in which it is located, provided that it supports this function.
Volume and format of SD memory card.
There are several types of memory cards in SD (Secure Digital Memory Card) format, which I have listed below in order of backward compatibility. That is, the previous memory card format in the list is backward compatible with the following ones and is not interchangeable in reverse order.
SD (Secure Digital Memory Card)- this is the very first secure format digital card memory. This type is compatible with all digital devices that support all of the following formats (SD, SDHC, SDXC).
- Maximum memory: 4 GB;
- Initial file system: FAT16.
SDHC (SD High Capacity) is the next high capacity SD memory card. This format works a little differently than the previous representative and is not backward compatible with devices that support the SD format.
- Maximum memory: 32 GB;
- Information exchange speed: 12.5 MB/s;
- Initial file system: FAT32.
SDXC (SD Extended Capacity)— another descendant of the SD memory card with extended capacity. This format has a different file system and is therefore not backward compatible with digital devices that only work with SD. Many devices released after 2010 should be compatible with this format. To finally make sure that the memory card is compatible with the device, look for the SDXC logo on the card and the device. In addition, a card reader capable of working with a format no higher than SDHC will not be compatible with SDXC cards. This format is not supported by all operating systems.
- Maximum memory capacity: 2 TB;
- Information exchange speed: 25 MB/s;
- Initial file system: exFAT.
SDHC I, SDXC I, SDHC II, SDXC II— a card with one of these logos has an increased data exchange speed due to improvements in the UHS bus interface. In simple and understandable language, we can say that UHS (Ultra High Speed) is an addition to the original SD format interface, which is improved by developers from time to time. It should be said that the host device will receive the maximum possible UHS speed only if both the memory card and the receiving device support UHS, otherwise they will be able to access the slower speed provided in the SD format.
- UHS I - has two architectures for the fastest data transfer of 50 MB/s and 104 MB/s. Here the developers have redefined the purpose of some pins to implement four-bit data exchange.
- UHS II - the next improved generation also has two architectures for high-speed data transfer of 156 MB/s and 312 MB/s. A four-bit data exchange mode is also used.
The maximum possible data transfer speed for the interface is indicated here, and you can find out the supported data transfer speed for a particular memory card from the specifications on the manufacturer’s website or from the information sticker on the card packaging. Full compatibility of UHS cards with digital devices that do not have the high-speed UHS protocol.
Since this SD format is aimed mainly at portable devices, it consists of three types. Each type of card has its own size.
For example, the standard SD format has a size of 32x24x2.1 mm, and miniSD has a size of 21.5x20x1.4 mm. The small microSD format has the most compact size of 11x15x1 mm, and with the help of special adapters this type of memory card can be adapted to the desired slot form factor.
Classes of SD memory cards.
Now let's take a look at what a memory card class means and what meaning this information carries for the consumer. So, under the classes there is information about the minimum write speed to the memory card. In other words, the higher the class of the memory card, the faster you can record and save voluminous information, play large audio and video files without interruptions and sound clips.
And to make it easier for consumers to navigate the speed capabilities of memory cards, the international SD Card Association classified them according to speed characteristics (multiplier) along with digital devices that can work with them, called SD Speed Class. The speed on memory cards is indicated through a special multiplier called a rating.
This figure is constantly growing, but this moment SD card multiplier from 6x to 633x. To make it clear, I will say that 1x = 150 KB/s. It turns out that the cards entry level have speeds of 6x = 900 KB/s, and top-tier SD cards have comparable speeds of 633x = MB/s. According to the speed specification from the SD Card Association, all memory cards are divided according to the minimum recording speed characteristics as follows:
- SD Class 2: write speed of at least 2 MB/s - multiplier 13;
- SD Class 4: write speed of at least 4 MB/s - multiplier 26;
- SD Class 6: write speed of at least 6 MB/s - multiplier 40;
- SD Class 10: write speed of at least 10 MB/s - multiplier 66;
- SD Class 16: write speed of at least 16 MB/s - multiplier 106.
It is the class of the memory card that is one of the important parameters when choosing a removable SD drive. In a previous publication, I touched on the topic of unscrupulous manufacturers, and in this case the SD memory card was no exception.
Unfortunately, there are “honest” manufacturers who indicate a multiplier on the map that does not correspond to the actual speed. That is, the card may actually have the speed declared by the manufacturer, but in read mode and not write mode.
To determine the multiplier of an SD memory card, you can conduct your own independent test using a card reader and a specialized program (for example, for Windows - H2testw; Linux - F3), and then compare the results with the table. You can also see how we did it, which can also be used to test SD and MMC cards.
| Rating/Multiplier (X) | Speed (MB/s) | SDHC class |
|---|---|---|
| 6x | 0,9 | n/a |
| 13x | 2,0 | 2 |
| 26x | 4,0 | 4 |
| 32x | 4,8 | 5 |
| 40x | 6,0 | 6 |
| 66x | 10,0 | 10 |
| 100x | 15,0 | 15 |
| 133x | 20,0 | 20 |
| 150x | 22,5 | 22 |
| 200x | 30,0 | 30 |
| 266x | 40,0 | 40 |
| 300x | 45,0 | 45 |
| 400x | 60,0 | 60 |
| 600x | 90,0 | 90 |
The speed class rating plays an important role for HD video mode, because in this case the digital device is in a state of constantly saving a stream of data to the memory card. It is the resolution and format that influence the number of stable data streams. Therefore, be sure to check the instructions for the digital device for the minimum speed class requirements for HD video mode.
How to choose an SD card.
As a rule, the speed class of a memory card on a simple SD format nameplate is indicated by a number inside the letter C, and for the UHS standard, the speed class is indicated by a number inside the letter U. Scope of application of the classes and compatibility with devices.
| Class | Write speed | Purpose |
| Class 2 | at least 2 MB/s | Recording video data for standard definition television in SD format |
| Class 4 | at least 4 MB/s | For recording HD (high definition) video, as well as Full HD (high resolution from 720p to 1080p/1080i). Entry-level digital cameras, game consoles and other devices that support SDHC cards. |
| Class 6 | at least 6 MB/s | |
| Class 10 | at least 10 MB/s | For Full HD (1080p) video recording and sequential recording of HD stills (high-speed data bus) |
| UHS Speed Class 1 (U1) | at least 10 MB/s | Capture Full HD video, 3D video, High Definition (HD) photos, and real-time broadcast recording |
| UHS Speed Class 3 (U3) | at least 30 MB/s | Recording video files for 4K television - UHD television (UHS bus). D-SLR and D-SLM cameras and video cameras with 4K or 2K support. |
And finally, I’ll say a few more words about the SD card compatibility mode. SDHC memory cards are not compatible with those digital devices that are originally designed only to work with SD cards, but those host devices (camera, video camera, phone...) that can work with SDHC cards are fully compatible with SD cards.
SDXC format memory cards should only be used with SDXC devices, as they will not work with SD / SDHC devices, but digital SDXC devices can use and support SD, SDHC and SDXC memory cards. SDHC host devices support both SD and SDHC cards memory, and SDHC memory cards can be used with SDHC and SDXC digital devices.
I hope I was able to tell you about something complicated in a simple way and you can now choose an SD card for your camera, video camera, phone, tablet, reader, and so on. Subscribe to new articles, there will be a lot of interesting things ahead. If you can add to the material or express your opinion, then by all means do so in the comments.
Do you know what the 10 in C, the 1 in U, and 300x mean on this card?
On mysku.ru, Vladimir Veretennikov (user Waldemarik) in a review of the MicroSD card (http://mysku.ru/blog/ebay/29690.html) wrote a whole treatise on memory card standards and notations. I took the liberty of dragging out the entire theoretical part from this review.
A little about the Secure Digital format standards:
— SD 1.0 is the very first standard, created in 1999 by SanDisk, Toshiba and Panasonic, as a direct competitor to another Memory Stick standard. This standard, in theory, implied storage capacities from 8 MB to 2 GB. File system FAT16.
— SD 1.1 is a further refinement of the standard, adopted in 2003. Among the features are an increase in capacity to 4 GB and a twofold increase in speed. File system FAT16/FAT32.
- SD 2.0 (SDHC, Secure Digital High Capacity, high capacity) - was created in 2006 to remove some of the limitations of old standards, in particular the insufficient capacity of drives. Thanks to this specification, the 4 GB limit has been removed and speed classes have been added (Class Speed Rating). It is now possible to create cards with capacities from 4 to 32 GB. The changes also affected the addressing scheme and the use of the FAT32 file system.
- SD 3.0 (SDXC, Secure Digital eXtended Capacity, extended capacity) - adopted in 2009, the maximum capacity was increased to 2 TB (capacity ranges from 64 GB to 2 TB), speed class 10 was added. The updated version of this standard SD 3.01 introduces an updated data exchange protocol (UHS-I), the data exchange speed over the interface is up to 104 MB/s. File system exFAT.
- SD 4.0 (SDXC) - appeared in 2011. According to the specification, a new data exchange protocol (UHS-II) has been introduced, and a number of new contacts have been added on the cards. Data exchange speed over the interface is up to 312 MB/s. File system exFAT.
Compatibility of cards and devices of different standards:
As we can see, older SD cards are supported on all devices, the speed is limited by the speed of the card. But if you insert an SDHC or SDXC card into a device designed only for SD cards (old photo/video equipment), the device simply will not see it. All standards have only direct compatibility (support for old formats), which is why my popular SDHC card reader Kingston MCR-MRG2 (previously included with all microSDHC Kingston cards) does not see the SDXC card (second line in the photo, SDHC devices see only SD and SDHC cards). There is only one conclusion, if the smartphone/telephone/tablet/player/photo/video camera, etc. do not support SD 3.0, you should not buy SDXC cards for them. Devices simply won’t see them!!! Conversely, even in the latest device with SD 3.0 support, you can insert and use old cards without problems, but there will be speed restrictions.
Small speed class plate microSD cards(indicate minimum write speed):
SD Class 2 - write speed of at least 2 MB/s
SD Class 4 - write speed of at least 4 MB/s
SD Class 6 - write speed of at least 6 MB/s
SD Class 10 - write speed of at least 10 MBs
SD Class 16 - write speed of at least 16 MB/s
UHS Speed Class 1 (U1) - write speed of at least 10 MB/s, theoretical ceiling - 104 MB/s, the speed can be any (updated data exchange protocol)
UHS Speed Class 3 (U3) - write speed of at least 30 MB/s (updated data exchange protocol)
Note: UHS Speed Class only applies to devices that support the UHS-I interface.
Manufacturers often indicate the speed rating as a multiplier, such as 13x, 40x, 300x, etc. How can this multiplier be converted into understandable MB/s? You just need to multiply by 150, i.e. 1x = 150 KB/s = 0.15 MB/s. As a result, we have 100x=0.15*100=15 MB/s, 300x=0.15*300=45 MB/s. For those who are too lazy to calculate, here are the most popular speed ratings:
13x - 2 MB/s
26x - 4 MB/s
40x - 6 MB/s
66x - 9 MB/s
100x - 15 MB/s
106x - 16 MBs
133x - 20 MB/s
150x - 22 MB/s
200x - 30 MB/s
266x - 40 MB/s
300x - 45 MB/s
400x - 60 MB/s
600x - 90 MB/s
Note: these multipliers are indirectly related to the speed class. Often, manufacturers mark the card's read speed in this way, but the write speed can be several times lower. Always look at the speed class first, and then at the rating (multiplier).
Since our card supports the UHS-I protocol, let’s try to figure out what it is (something with Wiki):
Data bus interfaces (protocols):
UHS (Ultra High Speed) bus is a high-speed data exchange protocol introduced in version 3 of the standard. The specification requires UHS cards and controllers to be backward compatible with earlier Normal Speed and High Speed interfaces.
The UHS-I interface (protocol) is defined in the technical description of version 3.01. Data exchange speed via the interface is 50 MB/s or 104 MB/s. Standard pins are used, but some pin assignments are redefined to accommodate 4-bit communication.
The UHS-II interface (protocol) is defined in the technical description of version 4.00. Transfer speed - 156 MB/s or 312 MB/s. Cards of this standard contain two rows of contacts - 17 for a regular card and 16 for microSD; a 4-bit exchange mode is used.
Depending on the conductor architecture, the maximum speed according to UHS-I interface may be different. The standard allows two options: up to 50 MB/s (SDR50, DDR50) and up to 104 MB/s (SDR104). The architecture is usually indicated on the blister (packaging) of the card. In our case, this is SDR50 mode interfase, i.e. transfer speed up to 50 MB/s:
There are devices that support the UHS-I protocol, therefore, in them, a UHS-I standard card will reveal all its capabilities, in this case speed (the protocol allows data exchange speeds of up to 104 MB/s). There are also legacy devices that do not know about the UHS-I protocol (created, for example, for the second or third version of the SD 2.0 or SD 3.0 standard), so there will be some speed restrictions. Familiar situation, fast UHS-I card and a cheap card reader that does not support the UHS-I protocol. The latter will greatly limit the speed, operating in High Speed mode (up to 20-25 MB/s), although the card is capable of more (see photos of modes above). In more understandable language, these are like USB 2.0/3.0 standards. That is, if the flash drive worked at the limit of its capabilities of 8 MB/s on the second version, then by connecting it to the third, we will not get an increase in speed (well, insignificant). So it is here (figuratively, for comparison). This is just a “startup” for the future, because 4K and 8K are just around the corner, and at today’s speeds, you need to wait a long time to transfer such a film to the card. As they say, if your card is “tailored” to a new specification, then zer good!
A small plate according to SD standards:
If the above is still not understood, then this is the same thing in simple words(it’s impossible to figure this out without a bottle :-):
There are regular cards, and there are cards that support the UHS-I protocol (Roman numeral 1). And there are devices with or without support for the UHS-I protocol. If some element is not supported, there will be restrictions.
Here is an example - a comparison of two identical microSDHC cards, but the latter has support for the UHS-I protocol (SD 3.01 standard):
In fast card readers that support UHS-I, the first card will be limited to Normal Speed or High Speed modes.
Another example of a Lexar 64 GB microSDXC card (the situation is similar):
A little about marking cards.
Since there are no uniform marking standards, all manufacturers label their cards differently. The most correct labeling of cards is the one that indicates the speeds for devices that support UHS-I and for regular ones. The speed for devices supporting UHS-I is indicated by the number 1 or 3 in the letter U. The speed for conventional devices is indicated by the number inside the letter C. Additional parameters are often indicated, in the form of a read speed of 300x-500x or a speed of Up to 45 MB/s.
Example of markings:
Toshiba microSDXC card (information content 3 out of 5). As you can see, the speed class is indicated only for conventional devices (number 10 inside the letter C), i.e. speed in conventional devices is not lower than 10 MB/s. Since the card supports UHS-I (Roman numeral 1), it lacks speed class when connecting via the UHS-I interface (number 1 inside the letter U). It is not clear what the minimum recording speed is in UHS-I mode. The actual recording speed is also unknown. But there is additional information on read speed, not higher than 30 MB/s.
Next microSDXC samsung card(informativeness 2 out of 5). As you can see, both speed class designations and the UHS-I specification icon (Roman numeral 1) are present, but there is no additional information about read speed. In devices that support UHS-I, it can vary widely, up to 104 MB/s. Here we only have a minimum write speed in any device (with/without UHS-I support) of at least 10 MB/s. The actual recording speed is unknown. Perhaps the reading speed is indicated on the packaging (blister).
More informative microSDXC Lexar (information content 3 out of 5). Both speed class designations and the UHS-I specification icon are present. As planned, 300x should mean write speed, which corresponds to 45 MB/s. Is this the real recording speed? Unfortunately no. The manufacturer is cheating again (*Up to 45MB/s read transfer, write speeds lower. Speeds based on internal testing. x=150KB/s), the “loud” numbers of 300x do not give anything, the write speed is unknown. Here 300x again means reading speed. The actual recording speed cannot be determined from the packaging.
Another microSDXC Transcend card (information content 3 out of 5). Both speed class designations and the UHS-I specification icon are present, as well as a read speed of 300x, which corresponds to 45 MB/s. Again, nothing is known about the actual write speed except that it is at least 10 MB/s.
And finally, the legendary microSDXC SanDisk (information content 3 out of 5). There is no speed class for conventional devices (the number 10 inside the letter C), although it is present on the packaging. There is also no speed rating, although the packaging shows Up to 45 MB/s (300x), in tests it shows about 45/80 MB/s for writing/reading and the price is around 3.5 kilo rubles:-(, but in a store with there is no way to know about this from the packaging.
Total: why didn’t one card receive 5 points for information content? Because manufacturers are cunning and almost always indicate the read speed (Up to 45-60 MB/s or 300x). In most cases, the write speed is important, it is the bottleneck, and it is indicated by a class that gives almost nothing (almost all cards provide a write speed of 10 MB/s). When buying in a store, you can easily run out of money and buy a regular budget card with a write speed of 10-12 MB/s (two cards with a U1 class can have different write speeds from 12 MB/s to 45 MB/s). One of the main guidelines is price. Therefore, there is only one conclusion: the information on the map/packaging does not indicate anything about the travel information and before purchasing it is better to look at speed tests on the Internet!
Before reading this text, I only knew about notation classes (a number inside the letter C) and something vague about speeds with an "x" at the end. :)
In my opinion, a very useful holiday reading. :)
For most people, microSD is just a form factor, but in reality it is not. You can easily insert any microSD card into a standard slot, but not all of them will work, since the cards differ in many ways.
Format
There are three different SD formats, available in two form factors (SD and microSD):
- SD (microSD) - drives up to 2 GB, work with any equipment;
- SDHC (microSDHC) - drives from 2 to 32 GB, work on devices supporting SDHC and SDXC;
- SDXC (microSDXC) - drives from 32 GB to 2 TB (currently maximum 512 GB), work only on devices with SDXC support.
As you can see, they are not backward compatible. Memory cards of the new format will not work on old equipment.
Volume
Support for microSDXC declared by the manufacturer does not mean support for cards of this format with any capacity and depends on the specific device. For example, the HTC One M9 works with microSDXC, but officially only supports cards up to 128 GB inclusive.
Another one is related to storage capacity. important point. All microSDXC cards use the exFAT file system by default. Windows has supported it for more than 10 years, it appeared in OS X starting with version 10.6.5 (Snow Leopard), Linux distributions support exFAT, but it does not work out of the box everywhere.
High speed UHS interface
An I or II is added to the UHS card logo depending on the version SDHC and SDXC cards can support the Ultra High Speed interface, which, with hardware support on the device, provides higher speeds (UHS-I up to 104 MB/s and UHS-II up to 312 MB/s). UHS is backward compatible with earlier interfaces and can work with devices that do not support it, but at standard speeds (up to 25 MB/s).
2. Speed
Luca Lorenzelli/shutterstock.com Classifying the write and read speeds of microSD cards is as complex as their formats and compatibility. The specifications allow you to describe the speed of cards in four ways, and since manufacturers use them all, there is a lot of confusion.
Speed class
The speed class macro for regular cards is a number inscribed in the Latin letter C The Speed Class is associated with the minimum write speed to a memory card in megabytes per second. There are four in total:
- Class 2- from 2 MB/s;
- Class 4- from 4 MB/s;
- Class 6- from 6 MB/s;
- Class 10- from 10 MB/s.
By analogy with the marking of regular cards, the speed class of UHS cards fits into the Latin letter U Cards running on the high-speed UHS bus currently have only two speed classes:
- Class 1 (U1)- from 10 MB/s;
- Class 3 (U3)- from 30 MB/s.
Since the speed class designation uses the minimum entry value, theoretically a card of the second class may well be faster than a card of the fourth. Although, if this is the case, the manufacturer will most likely prefer to indicate this fact more explicitly.
Maximum speed
The speed class is quite enough for comparing cards when choosing, but some manufacturers, in addition to it, use the maximum speed in MB/s in the description, and more often than not even the write speed (which is always lower), but the read speed.
These are usually the results of synthetic tests under ideal conditions, which are unattainable in normal use. In practice, speed depends on many factors, so you should not rely on this characteristic.
Speed multiplier
Another classification option is the speed multiplier, similar to the one used to indicate the read and write speed of optical discs. There are more than ten of them, from 6x to 633x.
The 1x multiplier is 150 KB/s, that is, the simplest 6x cards have a speed of 900 KB/s. The fastest cards can have a multiplier of 633x, which is 95 MB/s.
3. Objectives
StepanPopov/shutterstock.com Choose the right card taking into account specific tasks. The biggest and fastest is not always the best. In certain use cases, the volume and speed may be excessive.
When buying a card for a smartphone, capacity plays a bigger role than speed. The advantages of a large drive are obvious, but the advantages of high transfer speeds on a smartphone are practically not felt, since large files are rarely written and read there (unless you have a smartphone with 4K video support).
Cameras that shoot HD and 4K video are a completely different matter: both speed and volume are equally important here. For 4K video, camera manufacturers recommend using UHS U3 cards, for HD - regular Class 10 or at least Class 6.
For photos, many professionals prefer to use several smaller cards to minimize the risk of losing all the images in force majeure circumstances. As for speed, it all depends on the photo format. If you shoot in RAW, it makes sense to invest in microSDHC or microSDXC class UHS U1 and U3 - in this case they will reveal themselves fully.
4. Fakes
jcjgphotography/shutterstock.com No matter how trivial it may sound, but buying a fake under the guise original maps Now it's easier than ever. Several years ago, SanDisk claimed that a third of SanDisk memory cards on the market were counterfeit. It is unlikely that the situation has changed much since then.
To avoid disappointment when purchasing, just follow common sense. Refrain from buying from untrustworthy sellers, and beware of offers of “original” cards that are significantly lower than the official price.
Attackers have learned to fake packaging so well that sometimes it can be very difficult to distinguish it from the original. You can judge with complete confidence the authenticity of a particular card only after checking using special utilities:
- H2testw- for Windows;
If you have already experienced the loss of important data due to a memory card failure for one reason or another, then when it comes to choosing, you will most likely prefer a more expensive card a well-known brand than an affordable “no name”.
In addition to greater reliability and safety of your data, with a branded card you will receive high speed and a guarantee (in some cases even lifetime).
Now you know everything you need to know about SD cards. As you can see, there are many questions that you will have to answer before purchasing a card. Perhaps, best idea will have different cards for different needs. This way you can take full advantage of the equipment without exposing your budget to unnecessary expenses.
How to understand the card class, what UHS is and how to choose best map at the lowest price.
We will tell you everything using examples of Toshiba SD cards. All data is relevant for CF and other types of cards.
The card always indicates the card type, data transfer speed, card class and bus.
Types of cards
There are three types of SD cards:
- SD- the very first memory cards, compatible with all devices. Capacity up to 2 GB.
- SDHC - SD High Capacity— cards with increased capacity. Capacity 4 - 32 GB.
- SDXC - SD Extended Capacity— extended capacity cards. Capacity 32 GB - 4 TB.
Speed
For photography, the recording speed at which the camera will save data is important.
On cards, the speed may be indicated directly, for example 95 Mb/s.
You can also find cards in which the operating speed is indicated in multiples, for example 600x. The multiplicity is always the same x=150 kb/s.
100x = 100 x 0.15 kbps = 15 Mbps. This speed went back to CD-ROMs (things that existed before the iPod and long before the iPhone). The maximum multiple speed is 633x (95 MB/s). For CF cards, the maximum speed multiple is 1066x (160 MB/s).
For example, Toshiba EXCERIA PRO UHS-II 16GB. Read and write speeds are 260 and 240 MB/s, respectively. This means that a gigabyte of data will be written to the card in 4 seconds. The main thing is that your camera supports this speed and bus (you will learn about it below).
Card class
The card class specifies the minimum guaranteed streaming write speed. For example, Class 10 corresponds to a speed of 10 Mb/s.
For video, it is not the peak speed that is important, but the streaming recording speed, otherwise there will be frame loss.
Since 2009, additional classes U1 and U3 have been introduced for SD cards (based on the new high-speed UHS bus). The classes provide a minimum speed of 10 and 30 Mb/s, respectively.
Example. Toshiba EXCERIA UHS-I. The card uses UHS speed class 3, which provides a minimum speed of 30 Mb/s. and although its maximum write and read speeds are 60 and 95 MB/s, this card is capable of recording video at 4K resolution.
Below is a table of correspondence between class and minimum streaming recording speed.
SD recently developed new standards for card classes that will allow you to shoot video in 8K resolution.
What is UHS
UHS - (Ultra High Speed) ultra-high-speed bus that provides maximum recording speed.
- UHS-I supports speeds up to 104 MB/s
- UHS-II supports up to 312 Mb/s.
UHS-II cards can be identified by two rows of contacts.
Example
As you can see, the speed indicated here is 260 Mb/s. Roman I means UHS-I class. And U3 shows that the card supports 4K video shooting.
Which card to choose
- Shooting FullHD video using Class 10 cards or Class U1 cards from the EXCERIA series.
- Maximum Photo Recording Speed – Choose the fastest speed UHS-II cards from the EXCERIA PRO series.
- Shooting 4K video using U3 class cards from the EXCERIA series.
- High recording speed + 4K video shooting - U3 class cards and UHS-II bus of the EXCERIA PRO series.