为了获得更清晰的背景虚化效果，我把相机的光圈调到了f/1.8。

To get a better background blur, I set my camera to a wide ___f-stop of ___f/1.8.

为了获得更明显的背景虚化效果，他调低了相机镜头的f-stop值。

He lowered the ___f-stop on his camera lens to get a more blurred background effect.