Moment’s SuperCage Can Record ProRes Log Only to Very Specific SD Cards
Yesterday, Moment announced the SuperCage: a smartphone cage system with integrated USB-C and an SD card port. That might lead some mobile filmmakers to believe they can use their existing memory cards to take advantage of the iPhone’s ProRes Log capture, but as PetaPixel has written before, it’s not that simple.
Firstly, it should be noted that the SuperCage isn’t just for iPhone users — it will theoretically work with all modern smartphones (and for non iPhone capture, UHS-II SD cards are likely just fine). However, as is evident by Moment’s marketing imagery, the iPhone 15 Pro and 16 Pro series are the most popular for filmmaking because they support ProRes Log capture, which — when graded — can look as good as footage captured with some high-end, standalone mirrorless cameras.
In exchange, ProRes Log demands a huge amount of data. While 4K at 24 and 30 frames per second (FPS) can be captured directly to the iPhone, higher 60 FPS and 120 FPS options require external SSDs due to both speed and heat demands. Beyond that, ProRes Log files are big. Even shooting at lower frame rates, filmmakers will want access to removable storage for workflow purposes as well as the fact that most iPhones will run out of onboard storage quickly.
That’s where the dream of SD comes in. Many iPhone shooters already own SD cards because they have been the ubiquitous memory format in cameras for more than a decade. However, as that age should indicate, the technology is old. While cameras have improved and data rates have become more demanding, SD cards have stayed largely the same.
As a result, a vast majority of SD cards, and likely the cards most photographers already own, are not fast enough to handle the data requirements of ProRes log. While many will claim in big bold numbers that they have 250 MB/s or higher speeds, weak oversight by the SD Association and misunderstood performance numbers hidden behind terms like V30 and A10 means most general smartphone users have no idea how fast their memory cards actually are.
While SD cards are great if photographers and filmmakers want to transfer footage from an iPhone after capture, they are a terrible choice for direct recording with an iPhone shooting ProRes Log. However, first Anker and now Moment have released products that directly support the iPhone with an SD card reader. PetaPixel has already warned that it’s important to look at the limitations, but Moment’s entry into the space has changed the discussion a bit.
Two SD Cards are Capable of Supporting Some ProRes Log Capture
Before speaking with Moment, PetaPixel urged photographers to avoid using all SD cards to record ProRes Log with no exceptions. However, thanks to internal testing at Moment, that language is softening a bit. Moment’s lead product engineer Eric Riley spoke with PetaPixel yesterday and explained why it included an SD card slot into the SuperCage.
“When we first started this project I agreed with you 100%,” Riley says, referring to the use of SD cards with ProRes Log capture. “In the beginning, it was hard to even find an SD card reader that was fast enough, let alone an SD card that was equally up to the challenge. Things have changed a little since then though. It’s still not where I want it to be with industry implementation and SD card storage sizes but it’s a lot better.”
Riley says that Moment tested two memory cards that are capable of sustaining the write speeds necessary to capture ProRes log in 4K at up to 60 frames per second: the OWC Atlas Ultra V90 and the Sabrent Rocket V90. V90 refers to the SD association’s Video Speed Class, which is an indicator of an SD card’s sustained write speeds. The SD association doesn’t have a class above V90 — or the promise that write speed won’t fall below 90 MB/s — so not all V90 cards are going to perform the same. It just so happens that OWC — which makes some outstanding memory cards — and Sabrent are able to maintain a write speed of between 119 MB/s and 227 MB/s, according to Moment’s testing.
“We threw a barrage of testing at them because I didn’t trust them,” Riley continues. “I even had our app team write a custom program to scan the video output files for dropped frames. We cross-checked that custom app against all manner of slightly slower and much slower cards because again, I didn’t want to trust it at all. We also implemented a handful of PC, Mac, iOS, and Android apps to cross-check write speeds both for dummy file loads and actual filming.”
Riley says that, after the testing, he’s confident that these two memory cards can handle ProRes Log capture.
“After all of that, I can very confidently say that those two cards can absolutely record Apple 4K 60FPS LOG from the stock Apple app to the SD card for sustained amounts of time without dropping frames. You will run out of storage with the current generation of cards before the speeds dip too low,” Riley continues.
“Our app will have the ability to store footage directly to the SD card in Apple Log and a bunch of other log formats before the cage starts shipping. We have been using prototype builds of the app for the last year with these features.”
Of note, neither of these cards has been tested to support the iPhone 16 Pro’s new 120FPS capture. The data requirements for that slow-motion footage are twice that of the 60FPS capture, so SD cards simply can’t keep up.
You Can Use Them, But You Probably Shouldn’t
PetaPixel still believes SD to be the worst way to take advantage of the iPhone 15 Pro and 16 Pro video capability for a couple of reasons. One, the actual performance of SD cards is inconsistent and even if two cards from different companies promise the same speeds on the box, what they can output will vary wildly.
After speaking with PetaPixel, Moment agreed that its language around SD card support with the SuperCage was too broad and agreed to edit its Kickstarter to better explain the limitations. It also will remove references to any other SD card that it didn’t test; the original Kickstarter showed a V90 Angelbird card, but Moment hasn’t actually tested that card to certify its performance. Given that Angelbird dragged its feet on getting official CFexpress Video Performance Guarantee numbers, PetaPixel is hesitant to trust the brand’s ability to sustain high enough write speeds to handle ProRes Log, especially since it remains untested by Moment. A card simply stating “300 MB/s” write speed is not enough, as that is not an indication of sustained performance. The inclusion of this card in marketing materials for the SuperCage when it was not tested by Moment shows that even amongst experts, assumptions about performance exist.
Moment also added a section to its Kickstarter FAQ explaining that the use of an SD card comes with “heavy caveats.”
The second reason SD cards are a bad choice is cost: the aforementioned Atlas Ultra V90 card costs $120 for a 128GB card. The highest capacity option is 512GB and that runs a staggering $500. Sabrent’s Rocket V90 card is more affordable, but not by much. A 128GB card costs $90 while the 512GB option costs $450.
To put that in perspective, there are three SSD options that PetaPixel confirms support all ProRes Log 4K frame rate options (including 120 FPS): the LaCie Portable 2TB SSD, the Samsung T9 1TB SSD, and the OWC Envoy Pro Elektron 1TB SSD which cost $150, $135, and $180, respectively (there are of course other SSD options beyond these that work great, too). From a price-to-gigabyte perspective, neither SD card makes any sense by comparison. Beyond that, all three SSDs listed support ProRes Log at 4K 120 FPS, which no SD card will.
The main reason anyone would likely want to use an SD card to begin with is because they already have one and it is convenient. Out of all iPhone users and all SD cards in the possession of those people, it’s highly unlikely that the OWC or Sabrent card is among them, making the SD card port on the SuperCage effectively something a vast majority of users should ignore entirely.
Luckily, the SuperCage supports SSDs via any of the several USB-C ports on it. The cage looks extremely well made and Moment has an outstanding reputation for making great products. Beyond that, it seems to genuinely care about doing things right and the conversation with Riley this week solidified that belief. As long as a filmmaker knows enough about memory and storage, the SuperCage looks like a fantastic way to make using an iPhone, or any smartphone, for video capture a better experience.
Storage is Confusing
Camera enthusiasts, which make up a majority of PetaPixel readers, probably know everything that’s been covered in this story but because the iPhone — and all smartphones — attract very entry-level photographers and filmmakers, it’s important to restate these facts.
Because the SD card format plays host to such a wide range of performance metrics, it’s ripe for confusion. For example, there was a post on Threads last week from someone who thought there was genuinely something wrong with their SD card because it had a second line of pins showing. They thought that it looked like the card was broken and had no idea what UHS-II meant.
All of this clarification is important only for filmmakers who want to record in the highest possible quality on smartphones. For lower quality, non ProRes Log capture, an SD card is likely to be fine. But because the quality of ProRes Log footage is so good, most iPhone videographers are going to gravitate toward it — especially if they plan to buy something like the Moment SuperCage. That’s why having a constant discussion about storage options is so important.
PetaPixel will continue to do its best to keep discussing memory and storage. Simply by reporting and staying on top of this industry, the wild west of VPG in the CFexpress space got cleaned up within half a year. This publication has every intention of continuing efforts to increase knowledge and visibility into storage and memory to assure every creator never feels like they got a raw deal.
Image credits: Moment
