CFexpress 4.0 Specifications Announced
Just last week CompactFlash Association (CFA) announced the new standards for next-generation CFexpress 4.0 cards.
The new specifications will double the speed of current CFe cards (known as CFe 2.0 specs; don’t ask me what happened to CFe 3.0 I guess they just wanted to line-in the card specs with the PCIe version specs lol).
Now why is this exciting?
Firstly nearly all high end cameras now use CFe cards, but specifically the Type-B cards since they provide the best cost-size-performance ratio.
However Type-B cards do have a downside - it requires a special slot by itself (which is usually back-compatible with XQD specifications unless you’re using a Canon), and the slot while not as humongous as the old CF slots, definitely take up real estate as heat dissipation is a big concern for fast cards.
Enter Type-A cards, which have similar physical dimensions to the normal SD cards. This allows a single SD-card slot to accept either a SD card when inserted one-way, or accept a CFe-Type A card when inserted the other way.
Sony’s one of the major manufacturers doing it this way, and while it’s really a good move to bring CFe speeds to a higher end body while maintaining backwards compatibility with SD cards if needed, the cost-performance ratio is really bad as there’s only 1 manufacturer using it for consumer products now - Type-A cards are shunned by the other manufacturers due to the lack of speed (it’s only half that of CFe-B).
However now with CFe 4.0 specs, the Type-A cards have a theoretical max speed on CFe 2.0 Type-B cards - meaning whatever applications that CFe 2.0 Type-B could handle before without issues, the CFe 4.0 Type-A should be able to handle it gracefully too.
So just to put some numbers in for easier understanding:
A typical 45MP RAW file (14-bit lossless compressed) is 50MB
A fast camera can shoot 20FPS at full resolution = 50MB * 20shots = 1GB/s of data moving through
Currently the cameras when paired with pSLC CFe-B cards with high minimum sustained write speeds (usually in 1.3-1.5GB/s range) can fire away at 20fps all day and the camera internal memory buffer won’t fill up at all as the shots are offloaded as fast as they’re taken.
However using a CFe-A card, which have typical max write of around 800MB/s and sustained write of around 500MB/s some stuttering might happen as the buffer starts filling up and you will lose the 20fps.
The even larger culprit is the SD cards - certain camera models have a SD card slot as a 2nd card slot, and when a SD card is placed inside, it bottlenecks the entire process (if you’re writing to two cards at the same time) as write speeds for SD cards max out at 95MB/s (UHS-I) or 280MB/s (UHS-II). And also not to mention the disgusting pricing strategy of UHS-II cards.
So now back to the topic, the reason I’m really excited about the new CFe standards is because now manufacturers can have more motivation to put a hybrid SD+CFe-A slot as their 2nd slot, to maintain backwards compatibility and ease of use with SD cards, and yet not sacrifice too much in performance and speeds when needed to do a 2-card simultaneous shoot by using the Gen 4 Type-A cards.
Of course one can always argue that no matter the generation, the Type-B cards will always be twice as fast as Type-A cards, and the new Type-B cards will just open up even higher FPS shooting modes. Which brings me to the point - would you rather have an inferior SD-only slot as your backup slot where you’re locked down at 5FPS or so, or a hybrid SD+TypeA slot backup which can still shoot at 20FPS RAW which is the gold standard right now?
tl;dr I find this exciting news as on occasions I spray at 10-20 fps at my cat lol