Building on the earlier suggestion, I actually went through a bit of a trial and error phase when I first picked up my FX30. Tbh I was pretty stressed about the storage costs at first because these modern codecs are huge.

• I originally bought the fastest, most expensive card I could find, but it was so pricey I could only afford one tiny 80GB card. I spent more time offloading footage than actually shooting.
• After some DIY testing, I realized that for my documentary work, I needed capacity more than raw speed for about 90% of what I do.
• I switched my strategy and found that my current setup handles 4K 10-bit stuff perfectly fine without needing the absolute top-tier gear. I have been super satisfied using ProGrade Digital SDXC UHS-II V60 Gold for my general day-to-day shooting. It works well and I havent had any issues with overheating or buffering. For the times I really want to push the slow-mo at 120fps, I usually pop in the Kingston Canvas React Plus V90 which is a bit faster but still way more affordable than those Type A cards. No complaints so far, it just works.

ngl ive been through dozens of cards over the years and the one thing i dont do anymore is gamble with storage. learned that the hard way during a high-stakes shoot years ago where a cheap card just choked mid-take. the fx30 is special because it really pushes the limits of v90 cards when you are doing 4k 120p or using that xavc s-i codec. the sustained write speed is what actually matters, not the fancy numbers on the box. here is what ive found works best after testing a lot of different setups:

• ProGrade Digital SDXC UHS-II V90 256GB - these are my workhorse cards for 90% of my jobs. super reliable.
• Sabrent Rocket CFexpress Type A 1TB - if you need massive capacity for long docs or events this is the best value per gb.
• Sony TOUGH CFexpress Type A 160GB - i keep a couple of these for when i absolutely cannot afford a failure. honestly just stay away from the budget brands. the fx30 needs that high bitrate consistency to keep from overheating the card or dropping frames. spend the cash once and you wont have to think about it for years.

The FX30 has dual card slots - one for CFexpress Type A/SD and one for SD only. For the best performance (especially with 4K 120fps or 4K 60fps 10-bit), I'd recommend Sony's CFexpress Type A cards. They're expensive but bulletproof - I've never had a corrupted file. If budget is a concern, high-quality V90 SD cards will handle most shooting scenarios. I use a mix depending on the project requirements.

Same boat, watching this

CFexpress Type A card: Lexar CFexpress Type A Gold Series.

UHS- II V90 card: SanDisk Extreme Pro UHS-II V90.

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Are you planning to shoot a lot of slow-motion? If so, the absolute fastest cards are essential to avoid dropped frames. I'd highly recommend the Angelbird AV Pro CFexpress Type A cards. They're specifically designed for high-bitrate video and offer exceptional performance, even with demanding codecs and frame rates. The Delkin Devices POWER CFexpress Type A cards are another great option in this category.