The Sony a7 IV adds support for the much faster CFexpress Type-A memory cards in slot one.
However, currently only Sony and Prograde are making CFexpress Type-A cards, so they are ridiculously expensive.
So do you really need to use a CFexpress Type-A card in the Sony a7 IV?
Thankfully not, since the a7 IV also supports UHS-II and UHS-I memory cards in both slot one and slot two.
However, there are two instances when you will need to use a CFexpress Type-A card.
Shooting Video in S&Q Mode & XAVC S-I 4k (2x Slow Motion)
If you want to shoot in S&Q Mode with the file format XAVC S-I 4k, a record frame rate of 25p / 30p and a frame rate of 50fps /60fps (2x slow motion) then you will need a CFexpress Type A card. The a7 IV will not let you record in this specific format with a V90 card.
This is documented in the a7 IV Manual and I’ve also tested it myself.
That said, it’s a little odd because if I select XAVC S-I 4k, a record frame rate of 30p and a frame rate of 60fps (NTSC) then record for 10 seconds I get a 805mb file, so it’s recording at 80.5MB/s which is comfortably within the capabilities of a V90 card. What I’ve also noticed is that the bitrate drops to 250M (PAL) and 300M (NTSC) with these settings, it’s not possible to select 500M/600M.
But despite only recording at 80.5MB/s the a7 IV still insists that you use a CFexpress Type-A card. Maybe Sony just wants to sell more CFexpress Type-A cards? Or perhaps this will change with a future firmware update?
But for now, if you want to record with these specific settings a CFexpress Type-A card will be required I’m afraid.
Burst Shooting with Uncompressed & Compressed RAW Files
If you want to shoot continuous bursts in Hi+ Drive Mode with either uncompressed or compressed RAW files and not hit the buffer then you will require a CFexpress Type-A card.
If you use a slow UHS-II card like the Sony SF-M cards or a UHS-I card then you will also hit the buffer when shooting JPEGs and lossless compressed RAW files.
Please note that when shooting in uncompressed RAW, lossless compressed RAW, uncompressed RAW + JPEG or lossless compressed RAW + JPEG the maximum frames per second is reduced from 10 fps to 6 fps. This is why you will not hit the buffer shooting lossless compressed RAW with a UHS-II card but you will shooting compressed RAW.
Here are my in-camera speed test results using a 64GB Kingston Canvas React Plus UHS-II SDXC Memory Card and shooting to slot one in Hi+ drive mode.
|Image Type||Shots Before Hitting Buffer||Time to Clear Buffer (Seconds)|
|Uncompressed RAW (70.3MB)||26||3.85|
|Compressed RAW (36.6MB)||67||3.40|
|Lossless Compressed RAW (40.5MB)||Never hits buffer|
|JPEG Extra Fine (24MB)||Never hits buffer|
|Uncompressed RAW (70.3MB) + JPEG Extra Fine (24MB)||17||4.53|
|Compressed RAW (36.6MB) + JPEG Extra Fine (24MB)||24||4.26|
|Lossless RAW (40.5MB) + JPEG Extra Fine (24MB)||22||3.05|
For the price and performance the Kingston Canvas React Plus UHS-II SDXC are the UHS-II cards that I would recommend for the a7 IV unless you need the toughness of the Sony SF-G cards.
I’ve tested 14 UHS-II cards in the Sony a7 IV, you’ll find all of the results in my Sony a7 IV Memory Card Guide.
With the crazy price of CFexpress Type-A cards I’d definitely only recommend using them if you really need to.
Thankfully the a7 IV clears the buffer a lot faster than the a7 III does, so if you are shooting a lot of continuous bursts in RAW format you might find that UHS-II cards are still fast enough for your needs.