So the V90 advice is spot on, but if you're really worried about safety and reliability, you HAVE to look at the physical build of the card too. A lot of SD cards fail because the tiny plastic ribs or that flimsy lock switch break off inside the slot. > What specific SD card brands and models have you found to be consistently reliable... Imo, the absolute gold standard for the a7 IV is the Sony SF-G Tough Series UHS-II SDXC Memory Card. They are ribless and basically indestructible compared to standard cards. If you're shooting XAVC S-I (Intra-frame) at 4K/60p, you absolutely need that sustained V90 performance to keep the buffer clear. If the Sony Tough cards are too pricey, ngl the Kingston Canvas React Plus V90 SD Card is a fantastic alternative. I've used them for professional gigs for over a year and they've been rock solid. Afaik, 256GB is the sweet spot for 4K/60p; anything less and you'll be swapping cards mid-shoot. Since you have dual slots, I'd honestly recommend buying two and using 'Simult. Rec' mode for an instant backup. That's the ultimate reliability-first setup.

Honestly, I went down a massive rabbit hole benchmarking cards for my a7 IV because I basically refuse to pay the "Sony tax" if I don't have to. Tbh, the market has shifted and some boutique brands are actually outperforming the household names in terms of thermal stability during long 4K/60p takes. I eventually found that moving away from the mainstream stuff saved me a few hundred bucks on my 512GB setup. * Check ur codec: You only *need* V90 for XAVC S-I; for XAVC HS or S at 4K/60p, a high-end V60 like the Lexar Professional 1800x SDXC UHS-II is way more cost-effective.
* Thermal reliability: If ur doing long shoots, the Angelbird AV PRO SD MK2 V90 handles heat soak way better than most retail cards I've tested. It's reallyyy just about matching the card's minimum sustained write speed to ur specific bitrate requirements so ur not overpaying for overhead you'll never use. What bitrate are you planning to shoot at?

honestly im still pretty new to the a7 IV world but im also super nervous about losing my files so i spent way too much time looking this stuff up lol. before you jump in and buy the most expensive thing out there i think it helps to really look at how youre going to use the camera day to day because it changes the price a lot and i dont want to waste money if i dont have to. i have a couple questions to help narrow it down:

• how long are your typical recording sessions going to be like are we talking 5 minute clips or full hour long interviews?
• are you planning to back up to a hard drive every night or do you need the cards to hold everything for a long trip? since you mentioned being worried about reliability i basically spent hours looking at these two resources that really helped me understand the diy side of testing cards and figuring out what i actually needed:
• the official sony help guide for the a7iv has a specific bitrate chart that shows exactly which speed class you need for each setting so you dont overbuy
• alphashooters has a massive database of real world speed tests for this specific camera model which is great for comparing stats checking those charts made me feel way more confident than just guessing based on the box labels anyway i hope that helps you narrow it down

To add to the point above: i have been using the a7 IV for a while now and honestly im super satisfied with how it handles 4k video. but tbh instead of just taking our word for it you should really just check out some of the specialized benchmark sites. there are people who spend way too much time testing every single card for sustained write speeds and they usually have a giant spreadsheet you can look at.\n\njust google something like a7 iv sd card speed test and look for the reddit threads or the dedicated gear review sites. i remember seeing a killer youtube video about this a few months back too... just search for it and its gonna be right at the top. it shows exactly when the buffer kicks in for each card which is super helpful. i just picked one from their top list and i have had zero complaints so far. saves a lot of time vs trying to figure out which labels are actually honest lol...

With the a7 IV, be careful; I've seen reports of corrupted files with less reliable cards. I would suggest sticking with ProGrade Digital Cobalt series. I personally use the 128GB version, which cost me around $180 last year. Make sure it's the Cobalt line specifically, as the other ProGrade cards don't consistently maintain the necessary V90 (90MB/s minimum sustained write speed) for reliable 4K/60p recording based on my experience. I've never had a single dropped frame using this card, even after hours of continuous shooting. I'd also suggest formatting the card *in-camera* before each major shoot. A larger capacity might be tempting, but I prioritize reliability over pure storage space. I've found that managing multiple 128GB cards minimizes the risk of losing a whole shoot to card failure. Have you considered a card reader that supports UHS-II to speed up offloading?

Beyond the usual Sandisk/Sony recommendations, consider ProGrade Digital Cobalt cards. They're designed for sustained high write speeds, particularly crucial for extended 4K/60p recording on the a7 IV. Aim for a V90 rated card; this guarantees a *minimum* sustained write speed of 90MB/s, crucial for avoiding buffering. While others suggest 128GB, given your usage, I'd lean towards 256GB minimum. A ProGrade Cobalt 256GB currently runs around $230.

Alternatively, explore CFexpress Type A cards *with* a compatible reader. While more expensive upfront, they offer substantially higher speeds and longevity. This could future-proof your workflow. The Sony CEA-G160T (160GB) is an option. Are you planning on shooting in S-Log? If so, the larger capacity is even more crucial.