SD Association (SDA) today announced the latest evolution of SD Express memory cards doubling microSD Express memory card speed up to 2GB/s, plus four
www.businesswire.com
That's funny, I was literally checking the other day to see if the microSD Express standard had been updated to PCIe 4. I'd be curious to see if the power limits have changed at all for the microSD version. The current version of the spec doesn't seem to distinguish between regular SD and microSD, and has a sustained power limit of around 3W for a PCIe 4.0x1 link, which is what the microSD variant uses. That's a lot of heat to dissipate from a little 0.5g piece of silicon and plastic.
Also, the SD card association really loves throwing extra visual clutter on cards, don't they? Not that speed classes aren't useful, but this is the
fourth speed class system they have. Here's a typical SD card these days:
There are already three different speed class ratings on there:
- Class 10, meaning it supports at least 10MB/s sustained writes
- UHS-3, which is a different thing from UHS-III, and I don't think anyone really knows what it means
- V30, meaning it supports at least 30MB/s sustained writes
On top of this they're going to throw a completely separate E150 logo. They could have just extended the existing V classification to V150, V300, etc., but nope. Their claimed reasoning seems to be that the E speed classes include guarantees of performance with multiple streams of data, which the V classes didn't, but it's not exactly difficult to say "speed classes of V150 and up have extra requirements for multiple data streams". In reality, I suspect the reasoning is related to SD Express's awkward partial backwards compatibility. Because there's no BC with UHS-II mode, SD Express cards are going to be limited to V30 speeds in devices which don't support SD Express, meaning a V60 or V90 UHS-II card would actually be faster than an E600 card for anyone looking for an SD card for their camera.
This author seems to have an admitted personal vendetta against SD Express. It's kind of weird.
I think you can just set these articles aside and say the most obvious reason why SD Express cards wouldn't be used is the fact that they simply don't exist on the market.
It's a photography website, so it's not exactly surprising for them to point out that it's a dead format as far as cameras are concerned. Aside from the fact that CFexpress has already taken the high end of the camera market, SD Express lacks backwards compatibility with UHS-II speeds, and many photographers have spent hundreds of dollars on UHS-II SD cards which they would want to continue using. Many CFexpress cameras have better backwards compatibility with their SD cards than an SD Express camera would (eg Sony's cameras which have combo CFe Type A/UHS-II SD slots), so photographers aren't particularly eager for SD Express to become a thing.
Another factor is that the handful of SD Express cards that are actually on the market seem to be largely aimed at camera owners who don't realise their camera doesn't support them, and that a "slower" UHS-II card would actually be faster on their camera. With much of the existing SD Express market being little more than a scam aimed at unsuspecting camera owners, it's not too surprising to see photographers in general not being very supportive of the format.