SDHC / SDXC / SD cards

Advice on SD cards

What is an SD card?

An SD card has been one of the standard formats for storage media for years. They are available in several sizes and versions, such as a WLAN version, as well as a very small version for smartphones, action cams and the like. The memory cards are not this popular for nothing, they are relatively inexpensive and very robust, they can withstand adverse outdoor conditions such as moisture, heat or cold and still work without problems or data loss.

A memory card has a lock switch that puts the SD card into a write-protected mode, which is helpful if you still have important data on the card and want to make sure that you don't accidentally delete it. This lever can become loose over time and automatically "lock" the card so that it can no longer be written to.

Tip: With an SD card with WLAN support, older devices can also be made a little smarter and the images can be transferred directly. A newer standard here is the TransferJet.

Which memory card formats are available?

• SD card
• microSD card
• CFexpress
• XQD card
• Compact Flash
• MiniSD

There are various readers for memory cards, and there are now many combination devices that support over 30 different connections & types of different cards.

Tip: If you want to store your memory cards safely, you should use a memory card case, these are available in different designs so that they can store different models more often, but also cover different requirements, whether water-tight or compact.

What is which memory card for?

Micro SD memory card

• Smartphones
• Tablets
• Action cams
• Drones
• Handheld game consoles

SDHC / SDXC memory cards

• DSLR cameras
• SLR Cameras
• Compact cameras
• Scanners

Which SD card can have which storage capacity?

You may have asked yourself which capacity classes there are for SD memory cards and why SD cards are also called SDHC memory cards, SDXC memory cards or SDUC Standard.

Overview of the storage capacities of the classes

• SD Standard supports up to 2GB (FAT 12 or FAT 16 file system)
• SDHC Standard supports up to 32GB (FAT 32 file system)
• SDXC Standard supports up to 2TB (exFAT file system)
• SDUC Standard supports up to 128TB (exFAT file system)

What transfer speeds do the different memory cards have?

Memory cards are categorized into different speed classes, these are called UHS Speed Classes (Ultra-High Speed), which were first introduced in 2009 and have continued to evolve since then. The end devices in which a UHS SD card is inserted must support the UHS standard, otherwise the end device will use the older standard, the Speed Class standard. Anyone hoping to improve the read/write speed of an old device with a new card will be disappointed.

The UHS classes in the list:

• UHS-I - Theoretically up to 104 MB/s
• UHS-II - Theoretically up to 312 MB/s
• UHS-III - Theoretically up to 624 MB/s

The UHS standard is followed by the SD Express standard, which offers a write speed of up to 3940MB/s and uses PCIe Gen 3 & Gen 4 technology.

As an alternative to the UHS standard, the speed of video cameras is specified in Video Speed Class (V Class). This V Class designation is subdivided into the following groups:

• V6
• V10
• V30
• V60
• V90

Which SD card do I need for 4k?

For a video camera with 4K / UHD video resolution, you need a camera with a minimum V6 standard. Depending on how many frames per seconds (fps)/ frame rate (up to 120fps) & codec you record with, you need a minimum write speed of 60MB/s. You have maximum flexibility with a V30 or V60 card, which is also sufficient for some FPS rates in the 8K range.

Which SD card do I need for 8K?

To be able to write an 8K video resolution on an SD card, you need a memory card with the V60 or V90 standard. This means a speed of at least 90 MB/s. For 120fps, you need an SD card that supports 90MB/s, which corresponds to a V90.

How robust is an SD card?

SD cards from San Disk are known for their robustness. The manufacturer tests the memory cards under various adverse conditions such as the following: Frozen in a block of ice, 72 hours in salt water at a depth of 1 M, temperatures from 85°C to -25°C, the cards have been subjected to even more tests and have been dubbed virtually indestructible. Even drops or X-rays do not affect the SD card, meaning that the cards retain their data safely on the memory module even after one or more flights.