Using a reflector with natural lighting can be very useful when taking outdoors photos in various levels and locations of light. The reflector can direct and focus the surrounding light onto the face of the subject.

 

These are two examples of photos shot with and without a reflector. The photo on the left was taken with a reflector has a much clearer level of detail on the face of the subject due to the light being directed from behind the subject to the face. Whereas the photo without the reflector, on the right, is much darker and lacks depth and detail as a direct consequence of this.

These portraits were taken the open space of a riverside park area which allowed for a great quality of natural light, however they were taken during a heavily overcast day. the use of the reflector also highlights the contrast between the face of the subject and the greenery of the background.