R5 CFexpress Cards

David - Sydney

EOS RP
CR Pro
Dec 7, 2014
523
433
www.flickr.com
That's an awesome summary & testing... I put it in my bookmarks to reference later. Only nice thing would have been if they formatted the chart on wider monitors to display w/o scroll & they were consistent in the Tested Write/Reads vs Rated Reads/Writes.

I think the reason is in the explanation in the link...
"Where things get a little complicated, though, is that these speed ratings don’t necessarily reflect the absolute speed of the card. Put another way, a card that has a V30 rating isn’t necessarily faster than one that has a U3 rating. That’s because to display the rating on the card, the manufacturers have to have their cards certified for that rating. It also involves revising packaging and marketing materials, which is an expensive process. So not every manufacturer will go to that trouble and expense right away. The upshot is that it’s not as simple as just looking at a card with a V30 or even V60 rating and knowing that it’s faster than one that only carries a U3 rating. It might be, but the rating system doesn’t work quite that way. You can see evidence of that in the speed test results on this page, with some cards with a lower speed rating being faster in testing than ones that display a higher speed rating on the packaging."

Really happy I went with the ProGrade's now.
Sandisk's 64GB version does specify V30 on it but their 128GB version only has U3. Great testing that he does but weird about 128GB version.
 

SteveC

R5
CR Pro
Sep 3, 2019
1,957
1,796
Sandisk's 64GB version does specify V30 on it but their 128GB version only has U3. Great testing that he does but weird about 128GB version.
U3 and V30 both mean the same thing, 30MB/s. For some reason they felt the need to switch from "U with a number inside" to "V with a number ten times bigger next to it" to express exactly the same thing. Meanwhile, card manufacturers now have to put THREE distinct speed ratings on their cards now, all to say the same thing, because there are three overlapping scales C10 = U1 = V10. So basically any modern card will be C10 ( because the C numbers go no higher), U something bigger than 1, and V something bigger than 10.

NONE of which tells you the minimum sustained speed of a card, which is critical for large files (like video).

However...as far as I know these ratings are only used for SD cards?