TL;DR: Honestly, grab Sony SF-M Series Tough UHS-II SDXC 128GB V60 cards. They handle 4K 60p 10-bit perfectly unless you shoot All-I. Save ur cash for more gear!! peace 👍

Works great for me

No way, I literally just dealt with this yesterday. Small world.

Totally agree with David about the heat factor. I learned that lesson the hard way during a summer wedding last year. I was using a card that was technically fast enough on paper, but after about 45 minutes of intermittent 4k shooting, the camera just threw a write error and I lost the last few minutes of the ceremony. It was a nightmare honestly. Now I am way more cautious and basically never record to just one slot for anything important. I have found that even if a card says it can handle the bitrate, the sustained heat in some of those cards is a real gamble. For events, I would much rather have two slightly slower cards recording simultaneously than one bleeding-edge card that might cook itself mid-vow. Reliability is everything when you are on a paid gig, tbh. I just dont trust the specs alone anymore after that scare.

Saw this earlier but just getting back to the computer now. Before you drop a ton of cash, how long are your typical takes for these events? If you're doing hour-long continuous recordings versus short b-roll clips, the heat build-up is a way bigger factor than just the raw speed rating. I went through this exact same headache when I first got my current setup. I was basically obsessed with the specs and thought I absolutely had to have the fastest V90 stuff for 4K 60p. I ended up spending way too much on a couple of high-end cards, only to find out that for almost everything I do, the lower bitrate codecs (like the HS or S ones) look basically identical and don't push the hardware nearly as hard. Tbh, I actually ran into an issue once where my 'fast' card was getting so hot it gave me a warning mid-shoot, whereas my cheaper backup stayed cool because the camera wasn't working as hard to dump data. It really comes down to whether you're planning on using that All-I codec or not. If you're just doing standard Long GOP, you can save a lot of money. I mean... do you actually need the All-Intra for your editing workflow, or are you just looking for the best quality?

To add to the point above: it feels like everyone is leaning towards V60s to save a buck, but honestly, I had such a bad experience trying to do that. I bought a cheaper card recently and it was just not as good as expected, kept giving me write errors right when I thought I was finally getting the hang of 4K... super disappointing when you're already nervous about a shoot. The thing is, even if V60 works for some codecs, the a7 IV is really picky. If you ever want to use the All-I settings for better playback on your PC, the camera literally blocks you from recording unless you have a V90 card. I wish someone told me that before I bought three V60 cards that I can't even use for the high-end stuff now. I eventually had to get the ProGrade Digital SDXC UHS-II V90 256GB and it has been way more reliable for my peace of mind. I also tried the Kingston Canvas React Plus SDXC UHS-II 128GB V90 because it was cheaper than the Sony ones, and it has been solid so far. Just make sure you format the card in-camera every single time you start a new project. It is a bit of a DIY habit I picked up to avoid those scary database file errors. Better to spend a bit more now than have to explain a failure to a client later, imo.

Seconded!