Samsung Galaxy S6 - Manual (Page 60)

Applications
60
Separating the exposure area and the focus area
If bright light affects the contrast or the subject is outside the auto focus area, use this feature
to achieve an appropriate exposure. You can separate the exposure and focus areas and select
the exposure level you want for the subject.
1
On the preview screen, tap and hold the area to focus.
The AF/AE frame will appear on the focus area.
2
Drag the AF/AE frame to the exposure area.
The exposure area will be separated from the focus area.