What is an SD card and what are the types | Syntex.cz

What is an SD card and what are its types

Need to choose a memory card and don't know how to do it? Let's navigate through SD cards so that you make the right choice. Find out the difference between SDHC vs SDXC, as well as what write speed to choose to get the best results.

What is an SD card?

The acronym SD stands for Secure Digital and under this name you will find memory cards for phones, laptops, digital cameras and camcorders. With a memory card, you can expand the capacity of your device by up to hundreds of GB, as well as transfer data from one device to another.

SD card size distribution

You will commonly come across classic SD cards and the smaller microSD size, which is, however, perfectly full-size. The choice between a classic and a micro card depends on what slot your camera/camcorder has and what slot your computer has. So often a microSD and a reduction to a large SD are sold together.

Distribution of SD cards by capacity

While there used to be multiple types of memory cards on the market, today SD cards (and their smaller microSD variants) are virtually synonymous with memory for most devices. This is despite the fact that the original SD cards had a relatively small capacity and are virtually unused.

What types of SD cards are there?

- SD & microSD cards, which have a capacity of 8 MB to 2 GB, which is quite inadequate for today's needs.

- SDHC & microSDHC (SD High Capacity) cards, which have a capacity of 4 GB to 32 GB and are the successors to SD cards. You will find the minimum write speed markings already on them, which we will discuss later in the article.

- SDXC & microSDXC (SD eXtended Capacity) cards are the next generation of memory cards and have capacities of 64 GB to 2 TB.

So the fundamental difference between SDHC vs. SDXC and microSDHC vs. microSDXC is in their capacity as well as write speed.

Distribution of SD cards by speed

To choose the right card, it depends on what you'll be using it for. Shooting video in 4K resolution and above (or even RAW) is the most demanding and requires the fastest cards. Shooting is less demanding, although even there you shouldn't skimp on the card. It's always better to choose a slightly faster and larger card than you think you'll use.

You'll find several indications on SD cards that give an indication of their speed. Let's break them down one by one.

Class

For clarity, memory cards are divided into speed classes (Class). The class number lets you know the minimum guaranteed write speed. In terms of transfer speed, this is equal to or higher than the write speed on SD cards. For taking high-resolution photos, you should always get a card with a higher write speed to avoid delays.

UHS

The speed class doesn't stop there, you'll also find the UHS (Ultra High Speed) designation on the cards, which indicates that the card is suitable for cameras and camcorders with a USH bus. These cards are also compatible with cameras and camcorders without UHS, just not at their full speed.

What are the differences between them?

- SD without UHS can handle a maximum speed of 25 MB/s.

- UHS-I has a theoretical maximum speed of up to 104 MB/s.

- UHS-II supports a theoretical maximum speed of up to 312 MB/s.

- UHS-III supports a theoretical maximum speed of up to 624 MB/s.

Video Class

When purchasing an SD card for camcorders, then also look at the video class (Video Speed Class), which is indicated from the lowest V6 to the highest V90.

To get a clearer picture, check out the table where you'll find all the information lined up side by side.

To get a better idea, look directly at the example of what each character on the card means:

This 256GB card's SDXC designation means it works in any SDXC device.

The U3 designation means it can handle 30 MB/s write speeds on UHS devices.

The number 10, which you'll find in the circle next to it, means you can expect a minimum write speed of 10 MB/s on non-USH devices.

The Roman I indicates that it is UHS-I and supports a theoretical maximum speed of up to 104 MB/s

The V30 designation, on the other hand, means that you can record 4K videos on the card without any problems.

The 170 MB/s number then indicates the transfer speed.

Exascend memory cards boast a great price/performance ratio among SD memory card brands.