According to our long time trusted source, the long awaited Sony a7S III full frame mirrorless camera will be officially announced in late January, 2019. Currently, Sony has registered a new camera code WW715296 in Asia. So this camera code will probably a7S III.
According to previous rumors, Sony a7S III will have 4K@60p, HDR Video, Staked Sensor, you can take a look at rumored specs here.
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