As a thumb rule, when photographing reflections, use the smallest aperture possible (the largest f value); unless you want to capture a blurred reflection. In this photograph, I did want to frame in the entire tree crown, but the water body imposed constrains in doing that. Here I have used a f/8 aperture the smallest possible with my Sony-H7. Since the image is a reflection and the smallest aperture was used;a slower shutter speed had to be used, and to prevent camera shake, I did use a tripod. Now Since the water was still, the image turned out to be sharp, in case of a moving water body, then the above settings may not give the best results. In that case either use a higher ISO or a little bigger aperture.