See the wood from the trees

Last weekend’s stroll around Killiney Hill and Dalkey was an opportunity to savour some lovely spring weather, but as I wrote last week, the conditions were not optimal – at least at the time of day that I was out and about – for landscape photography.   On a bright sunny cloudless day, the best location for photography is often an area in the shade, which is being lit not directly, but indirectly from the sun-exposed areas around it.  There were no areas of total shade on Killiney Hill last weekend, and the area pictured was as close as I could find. And it wasn’t easy to work with.

In my minds eye, when I spotted it as we walked around the hill,  I thought it would photograph much better than it actually did.  I mustn’t have been thinking too hard, because the reasons why it didn’t, and the ways in which it didn’t, are all to easy to understand if you think about how light works, and how camera sensors respond to light. For a start, this being a wood (of sorts – at least a collection of trees) meant that the sunlight hitting the ground, and hitting the trees on its way there, was patchy.

The sun is a hard light source because it is so far away, which makes it small relative to any subject on earth.  Hard light is, essentially, small light.  Soft light is big light. You can make a hard light soft by making it bigger, and you (usually) make it bigger by diffusing it through some semi-transparent material – a softbox or an umbrella for instance, or by bouncing it off a larger surface to take advantage of the angles of incidence and reflection and the fact that light travels in straight lines.  That’s a subject for another post on another day, so if you don’t believe me, trust me for now.

For landscape photography, it’s difficult if not impossible to make the hard sunlight soft.  At least on a cloudless day.  If there are clouds, they will act as a semi-transparent material and diffuse the light.  On this occasion there were no clouds. And the patchy cover that the tress was giving was serving only to create patchy areas of lots of light and no light on the ground and on the trees.

So while shade, or cloud cover, might help reduce the extremes between the brightest and darkest areas in a photograph and so help your camera’s sensor keep everything within it’s limited range of black to white, a patchy cover of trees does nothing of the sort, and if anything exasperates the problem.

Consider if I took a photograph of the ground in the desert, with no trees overhead.  Yes, it would all be brightly lit by the sun, but I could adjust my exposure to bring it back within range of the camera’s sensor.  Similarly, if I took a photograph of the ground in a rain forest, with a total cover of trees overhead.  Now, while it would be dark, I could slow down my shutter speed, or open up my aperture, or increase my ISO, or do all three, and bring it back within range of the camera’s sensor.

All a patchy cover of trees, like I had decided to photograph beneath, does is take both extremes and slam them together into one photograph.  I can opt to expose for the sunlit bits, or the shady bits, but my camera, and no digital camera, is going to retain detail in both areas from a single exposure.

So what options are there? I can always decide to not take the photograph.  I can take multiple photographs at different exposures and merge them in a High Dynamic Range image.  I can take a RAW image and create multiple exposures from it for a pseudo HDR image.  I’ve done all three many times before.

There’s another option of course, and that is to take the photograph straight, exposing for what I feel is important in the scene, and sacrificing some of the less important (to me, at least) parts – typically at the opposite end of the dynamic range of the scene.

So if I decide the sunlit bits are important, I can expose for that and allow the shaded bits to go to black.  Or, as I decided here, I can retain detail in the shaded bits and live with the sky and other sunlit bits going to pure white. Of course, shooting in RAW means it’s not as bad as it might be and I was able to recover a surprising amount of highlight detail in the file when I brought it into Aperture for processing.

The end result is an image I actually quite like – at least more than I thought I would when I first started out.  Faced with a scene with lots of white and black it was difficult to know what to aim to reproduce and what to sacrifice, but once I decided what in the scene it was I was trying to photograph – I’ll avoid using the bad pun that is the title of this post at this point – things got a lot easier.