Sony A9 III ProFoto A1X and on-camera TTL Issue


Feb 19, 2024
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John Hanson
I have encountered a little issue happening when the ProFoto A1X (and possibly similar) is mounted to the a9 III's hot shoe and used for TTL flash.

The a9 III's max sync speed while using TTL is 1/500th. If you dial your SS past 1/500th, the camera automatically goes into HSS and the flash goes into full-dump mode. Easy enough.

The problem I found was; if you exceed 1/500th and then dial back to say, 1/160th, the flash sticks in HSS mode and continues to fire at full dump, completely blowing out your subject. If this happens (accidentally or on purpose) the solution I found is; cycling the flash OFF and ON. This will get your camera/flash back to working in your typical TTL mode. Not sure if this is a Sony issue, or a ProFoto issue. But it can cause a bit of panic in the moment...

As of today the firmware on my camera and A1x is up to date.
There was a thread on another site describing a way to fire faster than 1/500 without going HSS.

Key setting is in Exposure/Color menu (pink), Flash (4), Flash Timing Setting (scroll to second page of Flash settings).

If this is OFF, it will go HSS
If this is ON, it won’t.

Default setting is 0 microseconds, and it is worth trying that to see if you need a value. I think it’s the delay between firing the flash and capturing the image. You get to choose a value from zero to 1000 microseconds (1000us = 1ms. A whole millisecond!) in units of 20us.

I have not tried this yet - I should, because I might need it this weekend.

Chris Nicholls did a bit about this in his second video about the A9III.