The combination I use -- light green (#88FF88) on dark blue (#000060) -- is very easy to focus on. In particular, having roughly the same amount of blue in the

The combination I use -- light green (#88FF88) on dark blue (#000060) -- is very easy to focus on. In particular, having roughly the same amount of blue in the foreground and background makes blue, which is the color most subject to chromatic aberration, irrelevant for focusing.