Yes, the Samsung PRO Plus 256GB SD is compatible with the Sony Alpha A9 III.
Samsung Pro Plus is UHS-I V30. Meets U3 threshold for XAVC S HD (100Mbps). Cannot record XAVC HS 4K (280Mbps, requires V60 — UHS-I bus cannot achieve V60), XAVC S 4K (280Mbps, requires V60), XAVC S-I formats (require V90), or S&Q Motion (requires V90).
Conditions for compatibility
Compatible for stills and XAVC S HD (100Mbps, U3 met). Cannot record XAVC HS 4K (280Mbps, requires V60 — UHS-I bus cannot achieve V60), XAVC S 4K (280Mbps, requires V60), XAVC S-I 4K (600Mbps, requires V90), or S&Q Motion (requires V90). Full HD only for video.
“This camera supports CFexpress Type A memory cards and SD memory cards (UHS-I, UHS-II compatible).”
Last verified:
Confidence: inferred