Fisheye (hemispherical) photographs were taken in apple (Malus domestica Borkh.) tree canopies of varying types and analyzed for the percentage sky visible in the photograph. Canopy structure was evaluated with photographs along vertical transects, and seasonal development of different canopy forms was followed. Good correlations of the % sky to total and diffuse light, sunfleck penetration, red/far-red ratios, flowering and fruit coloration were found. Results were used to help define the proper balance between light penetration and interception by apple tree canopies, which was estimated as about 20% sky at the bottom of a canopy for ‘McIntosh’.