Behind the shot: Happy Landscape To you

Brügg (BE) Switzerland (2011), 17mm, f/4, 132s, ISO 200

This shot was an idea that came a cold summer evening in 2011.  I motivated a friend to come and help me preparing this apple tree with coloured ballons. Not a single cloud in the sky: the night was cold but perfect to catch the motion of the stars in the background. We walked in the fields during 20 minutes and arrived to the spot around 10pm (yes it was a late decision!). I took my photo material a Maglite torch for the light painting, a bag of balloons and a long string to attach the balloons to the branches. The night had fallen and climbing the tree was perilous due to the thin branches. We decided to go for a more radical way to "put" the balloons: we took a beetroot in the field behind, fixed the string with a half dozen balloons attached to it and threw it over the tree. A few ballons remained in the foliage and we repeated this a few times  (sounds easy now but our hands were already half frozen before starting to shoot).  We added a few balloons in the grass to get a nice composition and finally started to experiment the light painting. The painting was made by lightening the trunk of the tree and then its foliage. Short stops were made on each balloon to make them slightly brighter. The balloons in the grass were then lightened one by one by walking around in the scene.

Technical overview: I used my lens at its widest aperture f/4 (Canon 17-40mm f/4 L USM) to get a reasonable time of exposure (to see the stars motion, avoid to have too many blurry balloons due to the wind and to have the time to paint the whole scene with the torch) of approx. 2 minutes at 200 ISO. The 200 ISO is low enough to avoid noise. Even if the aperture is wide open, the depth of field (DoF) is infinite with a wide angle lens at 17mm for a subject at approx. 5m. Check this very useful link to calculate DoFs: http://www.dofmaster.com/dofjs.html