When buying a memory card, we often only consider the card type. For instance our camera or device takes a certain type of card, like XQD, CFexpress, CFast, SD, micro SD etc. However, the decision on what card to buy does not stop there.
Card Capacity
Some devices like older cameras and trail cameras can only take certain size cards. There may be a max size (GB) that it can take.
Today’s card capacity can go beyond gigabytes (GB) to terabytes (TB). Camera that produces 4K and 8K video requires large and fast cards.
Card durability
· Some cards are more durable than others in general. Some professional cards have metal casting instead of plastic casting. Some cards have protection from moisture and magnetic interference.
Card Speed -- Transfer Speed (not WRITE SPEED)
UHS (ultra high speed)
UHS-I Transfers up to 104mb/sec
V10 and V30 card
Uhs-II Transfers up to 312mb/sec
V60 and V90 cards
UHS-III transfers up to 624mb/sec
Video Speed
V10 10mb per second
Ideal for still photography
Full HD recording 1080p at 30fps
V30 30mb per second
4K video at 30 frames per second
RAW photo in burst or rapid-fire mode
V60 60mb per second and V90 90mb per second
6K and 8K video
Time lapse
Simultaneous capture of raw and jpg images
Multiple video streams
Class
Older way of indicating the speed of the memory card. Minimum speed for modern equipment would be Class 10. If your memory card less than Class 10 it would be a good time to replace it.
Class 2---2 mb per second
Class 4--4 mb per second
Class 6--6mb per second
Class 10--10mb per second
Other Speed Concerns
Write vs Read Speeds
Write speeds are the most important since that is the speed at which data in captures on your memory card.
Write speeds are often slower than read speeds so when comparing cards only compare write speeds to determine the better card.
Be aware of maximin, minimum and sustained speeds especially on large capacity drives. Sustained speeds can be dependent on buffering in the camera as well as the card. Often the read speed is the maximum speed while the write speed in the minimum or sustained speed.
Research the true speed of your memory cards --try these websites.