re: The Camera Market is Down to Two 35mm Format Contestants: Sony A1 and Canon TBD
re: Sony A7R IV: Which High-Speed and High-Capacity SDXC Cards Are Best?
re: TESTED: Sony 80GB CFExpress Type A Camera Storage Card
Each slot is the same. Each slot can take either CFExpress or SDXC. There are some restrictions on auto-transitioning from one card to the next while recording video, but for stills it can be two the same or one of each.
The CFExpress slot trounces the SDXC slot for bandwidth, so if you’re going to be banging out 30 fps raw files and/or you want hyper-fast downloads of 8K video, CFExpress is the only rational choice. Recording 8K video can be done to a fast enough SD card, but that seems a dubious choice at best. And if you’re spending $6500 for a camera, skimping on storage makes no sense unless you’re just shooting stills at low capture rates.
UPDATE Dec 2021: the OWC Atlas S Pro SDXC cards are top notch, and even a little faster than the Sony. I am switching to them. See TESTED: 256GB OWC Atlas S Pro SDXC Card (plus comparison to Sony TOUGH SF-G).
UPDATE: I’m going to skip the CFExpress Type A cards for now until prices come down. I’m going to pay $398 for a measly 256GB card plus another $118 for a Type A card reader ($516 total!). I’ll just use the Sony TOUGH SDXC cards for now ($115 for 256GB, or $190 for the 128GB card rated at 299MB/sec, see below).
I just bought a blazingly fast Sony 512GB CFExpress card and the Sony MRW-G1 CFexpress Type B/XQD Memory Card Reader. Ouch on the cost, but the CFExpress card should be good in an increasing number of cameras and I expect it to become the standard for all new high-end cameras within a year.
Update, I goofed on my order, which I’ve canceled: the Sony A1 needs a CFExpress Type A card. Most cameras (Nikon, Canon, Panasonic) need a type B card—incompatible. And type A cards are half as fast as Type B cards. And it means I cannot use the XQD cards I have. Pretty sucky overall with yet another card reader neede—yuck!