The best memory cards for the Sony FX3

Choosing the best memory cards for the Sony FX3 can or A7SIII be tricky so in this post I’m going to look at the best options. I’ll describe how each card type could effect your use of the camera and the choice that I made for my FX3.

best memory cards for the Sony FX3 or A7sIII

Card Types

The Sony FX3 uses a clever slot design that’s capable of utilising either CFexpress Type A or SDXC UHS-II cards. While the camera does accept either card type you need to choose carefully based upon your intended usage as the slower cards will limit the cameras capabilities.

Let’s begin by looking at the speed of each type of card.


CFexpress Type A

best memory cards for the Sony FX3 or A7sIII - Type A

The new CFexpress Type A cards offer the fastest read and write speeds of the the two options. Sony’s own brand ‘TOUGH’ cards for example list write speeds of 700 MB/s and read speeds of 800 MB/s.



best memory cards for the Sony FX3 or A7sIII - V90

SD cards have been around for ages but they are not all created equal! The Sony FX3 will work with slower SD cards but with more limited recording options.

I’m going to assume you want the best cards for your camera so I’ll use the Angelbird SDXC UHS-II v90’s in my comparison.  The UHS-II V90 card has write speeds of 260 MB/s and read speeds of 300 MB/s.


So the CFexpress Type A is best right?

Without doubt the CFexpress Type A cards offer the fastest of the two options. You’ll need to decide however if the additional cost is worth it for your uses. Let’s put this in to perspective with some current prices as of writing this post. The prices shown will change over time so click the provided links for the latest prices.

Sony 80GB TOUGH CFexpress Type A – $198 ($2.45 per GB) – latest prices

Sony 160GB TOUGH CFexpress Type A – £398 ($2.48 per GB) – latest prices

Angelbird 128GB AV Pro SDXC UHS-II v90 – $160 ($1.25 per GB) – latest prices

Angelbird 256GB AV Pro SDXC UHS-II v90 – $400 ($1.56 per GB) – latest prices

As you can see there’s currently a big difference in the prices. The CF Express type A cards cost almost twice as much per GB as the SDXC V90 cards. You also have to factor in offloading  the cards to your computer. SDXC v90 cards will work with most existing SDXC card readers however the CFexpress Type A cards require a dedicated card reader such as Sony MRW-G2. The MRW-G2 currently retails for around $120.

The Sony MRW-G2 Type A Card Reader


What difference does it make in the camera?

If you choose the SDXC v90 cards you wont be able to access all of the recording features that the FX3 offers, but you won’t be as limited as you might expect!

The only recording option you won’t be able to use with V90 cards is the XAVC S-I (Intraframe) codec using the S&Q (slow & quick motion) at 100 or 120 fps. All of the standard recording options (non S&Q) up to 4K XAVC S-I at 50/60 fps will work fine with the SDXC V90 cards.

When using SDXC v90 cards you can still shoot at 100/120 fps, you just need to use the 4K 10 bit 4:2:2 XAVC HS codec instead. In my experience the XAVC HS codec offers similar quality to XAVC S-I but at the cost of requiring more processing speed or transcoding in post production.


Proxy considerations!

One of the little mentioned features of the Sony FX3 is the ability to record smaller proxy files at same time as recording the full quality files. As this requires additional write speed from the cards it will also be effected by your card choice.

When using SDXC V90 cards you cannot write proxy files at the same time as recoding the best quality XAVC S-I files in either 4K or HD. If you’re looking to record proxy files at the same time as shooting in the best quality XAVC S-I codec then you’ll want to choose the CFexpress Type A cards.

Using the SDXC V90 cards you can still record proxy files when using XAVC HS or XAVC S as the main codec at up to 50/60p. Recording proxy files at the same time as shooting 100/120 fps is not possible with either card type.


If price isn’t a factor then the CFexpress Type A cards are the best option for the Sony FX3 because they allow all recording modes and features to be used.

If you don’t need to use the XAVC S-I codec at 120fps or XAVC S-I with proxies then the Angelbird SDXC V90 cards offer a big saving and could be the better choice.


My choice

I decided the best memory cards for me were the Angelbird 128Gb AV Pro SDXC V90 cards as they offered the best price per GB. The ability to shoot at 120 fps using XAVC S-I wasn’t worth almost double the cost when 120 fps in XAVC HS offers similar quality at the expense of some rendering time in post.

My 2015 iMac Pro can fluidly edit the 4K XAVC S-I footage just fine so there is no need for me to record proxies when using that format.

Whichever type of card you decide to use I’d recommend buying them in pairs as then you have the ability to shoot to both card slots at the same time to protect against data loss.


Sony TOUGH CFexpress Type A Cards:

80GB – get prices

160GB – get prices


Angelbird SDXC AV Pro v90 Cards:

64GB – get prices

128GB – get prices

256GB – get prices

128GB Twin Pack – get prices

256GB Twin Pack – get prices

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