The Sony A90K's SDR peak brightness is just passable. Like all OLED TVs, it has an aggressive Automatic Brightness limiter that makes large bright scenes dimmer, which isn't ideal if you use it as a PC monitor or watch sports like hockey. It also automatically dims static content, like the HUD in some games, as a burn-in prevention method. This 48" model is slightly brighter than the Sony 42 A90K OLED, but the difference isn't noticeable with real content.
These results are from after calibration with the 'Custom' Picture Mode, Brightness at its max, Contrast at '90', Color Temperature on 'Expert 1', and Peak Luminance on 'High'.
If you want the brightest image possible and you don't care about accuracy, then use the 'Vivid' Picture Mode with the Brightness and Contrast at their max, Live Color, Advanced Contrast Enhancer, and Peak Luminance on 'High', and the Color Temperature on 'Cool'. It results in a peak brightness of 766 cd/m² in the 2% window.
