Smoke and mirrors

I promised a few more landscape shots over the coming days, albeit ones in a portrait format.  This photograph was taken from Sandymount strand early last December as I was on my way into the city centre to take some shots of the Christmas tree on O’Connell Street.  I had only taken a flimsy portable tripod with me onto the strand, and with light fading fast, there was no time to retrieve a sturdier tripod from the car.  It’s a wonder therefore that I got a shot that was in any way sharp.

The problem was that, due to the low light levels, I needed a long exposure.  That long exposure required the camera to remain rock steady, but the tripod wasn’t inclined to cooperate as it strained under the weight of the reasonably hefty D300.  After a few failed attempts, this exposure was my “one last go”, and for some reason, had enough sharpness to be useable.

The difficulties created by the long exposure were entirely my own doing, and came back to the fact that I set my aperture first, and let the shutter speed be what a proper exposure dictated. By any standards, f/22 is quite a small aperture, and when exposing an image the narrower the aperture (i.e. the bigger the f/ number), the less light hitting the sensor, and so the longer the shutter speed required.  There is another variable to play with in exposure – ISO – which amplifies the sensitivity of the sensor.  However, at ISO 800, I had gone as high as I was comfortable with before I’d have to really worry about noise.

So why did I set the aperture first, if the shutter speed proved problematic?  Well the aperture impacts on two characteristics of a photograph, and I was after very specific results.

The first characteristic is depth of field.  The narrower the aperture, the larger the depth of field, and so the more of the photograph will be in focus.  For a landscape shot this is often very important, and indeed it was a consideration here.

The second impact of the aperture choice isn’t so obvious, but it’s to do with the shape of the opening that the light comes through to hit the sensor.  You might think this isn’t a consideration as it’s not likely to noticeably impact the final image, and mostly that is true.  For dusk or night time photography however, the shape of that opening (which is directly related to the aperture) dictates how light sources in the frame will be represented.  A wide aperture will give you a fuzzy blob, but a narrow aperture will give a star-burst effect mimicing the shape of the opening during the exposure.  Looking at this image, you can see this effect to the center right of the image. More so than a large depth of field, getting that effect was in my mind when taking this shot.  The cost of achieving it was the 2 second exposure.

Thankfully, on that “one last go”, all the variables came together for that 2 seconds to produce the desired effect.

A final note on the composition which breaks the “rule of thirds” which very often for landscape photography is sacrosanct.  The only possible shot I could see here was a composition which showed the reflection of the smoke in the wet sand, and the only framing that made sense to me for that was to place the horizon bang in the middle of the photograph, breaking that rule.  I think in this instance it was worth breaking.