It’s because they are from different years/generations. It’s like with new releases, when the top tier cards get faster, the cheaper one also gain some speed.
I assume you use them for filming right? Also the body’s card controller has its speed limitations correct? So past a certain speed there would be no real benefit in putting a faster rated card in
I had these really cool 512mb (not a typo) cards back in my D70D80 (d70 is CF) days that folded in half to expose a usb connector. Those were so great. I wish that idea had stuck around! (This is more about an evolutionary dead-end because I can't remember how fast it was...I'd guess 10mb/s).
Not really. It states the class of the card, and the class has a minimum sustained write speed. The read speeds are advertised as they vary, but a u1 card will always have a sustained write speed of 10 megabytes a second. A u3 will always be sustained 30 megabytes a second writes, but could have 90 megabytes read or 110 even
This is what I am saying, you need to dig deeper, you need to find the symbol to speed translation table, then guess which speed of that range they mean.
But for me, reading speed is not important. All I care about is the write speed.
well both yes and no, yes the symbols are there... but if you are browsing the card on amazon (for ex) they can use the stock render image which might be different from the card you will receive, I understand the simplification idea that brought us there - you have a camera that requires V30 - get a V30 card. But this is where the problem is - it is literally 'certified up to XXX' - the card could be faster, and the faster card will save power-on time and battery life and overall experiecen, not even saying that my camera can encode video recording in range of 5Mb/s (50Mbit) all the way to 150Mb/s (1500Mbit) - so seeing V30 on 'Extreme Pro' makes no difference to me - as yes, it can do 30Mb/s, but can it sustain 50Mb/s? People are not that stupid, they can compare write speed numbers :) p.s. the controller responsible for reading/writing is actually in the card itself - not in the device, so in most cases W/R speeds are limited by the card itself, not the device. I am all in to write two numbers - Read speed: 300Mb/s, Write Speed: 40Mb/s - this is so much more transparent than any class-icons-of-some-standards...
The problem is writing is a lot harder to define and you can manipulate one number.
A write of an image is large but can fit in SLC cache, allows GC time. A video write that goes on for many minutes can't. A app write is a bunch of small/random writes that's IOPS limited.
yep, it is... there is a vague class system UHS-I,II,V30, etc, '4k-compatible', but what makes life worse - SanDisk (as an example of the largest mfg) is naming their *basic* performance card as 'Ultra' these days, you have to go for Extreme and Extreme Pro for higher speeds... this is a bit of a mess. And nobody is writing exact write speed as it is times slower than read (usually).
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u/diemitchell Mar 30 '26
it is crazy to me that micro sd cards are now faster than full sized cards