Earlier we saw Carl Pei teasing the portrait mode of the upcoming OnePlus 5T and rumors have suggested an upgraded hardware. A camera review posted before the official unveiling reveals what the rumors did not – that 5Ts dual camera will drop the zoom lens.
Instead, the second sensor will focus on low-light photography and portrait mode. It reportedly has the same field of view (i.e. no zoom) and the same f/1.7 aperture as the other sensor. Its resolution was increased from 16MP to 20MP though theres no additional OIS for it.
OnePlus 5T (left) vs. OnePlus 5 (right)
The eager testers found that the OnePlus 5T switches over to the second camera at around 3.5 lux (quite dark). As you can see that helps the image quality the 5T does notably better than the OnePlus 5.
As for the bokeh of portrait mode, it doesnt look like a massive improvement over the current model. Portraits of humans (with no stray hairs) turn out better, but the edge detection of the digital bokeh still leaves something to be desired (e.g. it failed on trees).
Source (in German)