For 1080P video, Class 6 (recording 24 frames) and Class 10 (recording 60 frames) memory cards are sufficient, while memory cards lower than Class 6 cannot record 1080P video without frame loss.
When recording 4K video, you basically need a memory card with a speed grade of Class 10 (very far-fetched) to V60 to be able to record. Basically, you need at least a U3 (minimum writing speed of 30MB/s) memory card to be able to record.
As for the recording of the legendary 8K video, a memory card above V60 is required to support it.
The criterion for determining the speed level is the writing speed, not the reading speed. In many cases, the most important factor affecting the performance of the memory card is not the writing speed but the reading speed, such as the loading speed of game consoles such as switches is to test the read speed of the memory card. Therefore, users should choose the appropriate memory card according to their needs, instead of blindly pursuing ultra-high writing speed.
The types of SD cards are classified according to their storage capacity. The SD cards below 2GB are called SD cards, which have been basically sifted out. Now the market is basically filled by SDXC cards (32GB and above) and a small amount of SDHC cards (2GB to 32GB). The corresponding mobile phone memory card can be added with micro in front. For example, the terminological name of the card used in the camera should be SDXC memory card, but everyone is habitually calling it SD card.
In addition, different types of memory cards use different bus frequencies. Starting from SDHC, it has supported UHS-I and the more advanced UHS-III bus interface. The memory card that supports UHS-III can reach a speed of 624MB/s, and the SSD equivalent to the SATA3 interface. The newly released SD Express standard, the speed can reach 3940MB/s, has reached the speed of M.2 SSD. And even the ordinary UHS-I has a speed of 104MB/s, which can basically run at the maximum read and write speed of most memory cards.
If the memory card supports UHS-I, for the reading device that supports UHS-I, the maximal speed of 104MB/s can be approached. At this time, it is not the memory card itself but the reading device that restricts the transmission speed. If you use UHS-Ⅱ reading equipment, the maximal reading speed of 170MB/s this memory card can reach.
It should be noted that only card readers that support UHS-I will be marked in a prominent position that they support UHS-I. Readers that do not support UHS-I will generally only emphasize the USB3.0 speed.
If you check on the same brand from the same sales channel, the price of a card reader that supports UHS specifications is three times expensive than of a card reader that does not support UHS specifications, so if you want to use your own idle memory card with a card reader as a USB flash drive to use, you need to buy a matching card reader to be able to play its max. speed.
Regarding the choice of card reader, I personally recommend directly starting a card reader that supports UHS-Ⅱ. After all, whether it is an ordinary user or a high-end user, there will be the possibility of upgrading the SD/TF card in the future, instead of purchasing a new card reader, it is better to buy one with bigger reading potential and to avoid unnecessary waste.