Maximum SD card size for A7RIII and A9

[2xbass]

Has anyone used cards bigger than 256GB in slot of an A7RIII or A9? I can’t seem to find any documentation that indicates 512GB would be a problem.

[Chrissie]

I have a 128 GB card in my A9, so cannot report actual experience. No issues with the 128GB card so far.

From a technical point of view:

Since the technical specification of SD cards v2 is from 2007, v3 from 2011, and both a9 and a7riii are from 2017, I would naïvely assume, that both cameras implement the full SDXC standard, which allows for up to 2 TB. I'm not aware of any additional (lower) limit imposed by Sony.

From a practical point of view:

• why would you want to use such a huge card anyways? a 512GB card is more expensive than 2  cards of 256GB, which are more expensive than 4 cards of 128 GB, and so on.
• 64 GB is sufficient for 1.000 images of uncompressed raw + jpeg. By extension, 512 GB would be good for 8.000 images.
• You run an extended risk of loosing up to 8.000 images, if something goes wrong with one huge (521GB) card.
• Continuous video recording is limited to a maximum of 29 minutes, because of the 4GB file size limit, and a 64GB card provides already for up to 1 h 15 Minutes of video at the highest quality settings.
• And then there is the overheating problem when continuously recording video for an extended time.

I'm honestly curious about your use case.

[2xbass]

Thanks for your reply. I meant to write “slot 2” in my original post. I use 64 GB cards in slot 1 but keep backing up to slot 2 across multiple shooting sessions where I might not have a chance to otherwise backup to another device. I currently use. 128 GB card in slot 2 of one of my cameras and recently filled it after a couple of sessions of wildlife shooting.