Location

This photo was taken with my Canon EOS 350D at 17:45 on 28 Dec 2007, on a bridge over the M23 (junction 10a), near Crawley. Although ideally I would have steadied the camera with a tripod, I actually used one of the posts of the metal fence/guard along the edge of the bridge to support the camera during the exposure.

Lens and Exposure

I used my 18-55mm lens at a focal length of 35mm. The exposure was 30 seconds at f29.0, long enough to capture a number of vehicles travelling in each direction to give the streams of light, but with a narrow aperture to prevent over-exposure on such a long shutter. The narrow aperture also caused the starburst effect at the converging point due to diffraction of the light within the lens, something that wouldn’t have occured at a lower f stop.

Unfortunately I used ISO 1600 which is far too high and so there is some graininess to the image. With hindsight I would have used ISO 100 or 200 and used a much longer exposure (on bulb mode) to capture a similar image with less noise. It may also have exposed the sky more which had a very interesting purple tinge that evening and is just noticeable in the shot. However as the temperature was hovering about 2-3 degrees, we were quite keen to move on as soon as possible!

Fine tuning

Post production editing of the photograph was done using Google Picasa and involved simply darkening the shadow areas to increase the contrast of the image and remove some the unnecessary and noisy detail in these areas.

Another option to get the most our of the various photos that I took at different exposures, would be to layer them all together in an image editing app (e.g. Photoshop) and use layer masks to pick out the best bits, e.g. the sky from one, the light trails from another. This was a tip I picked up from Digital Photo‘s Jan 08 edition. Unfortunately because I wasn’t using a tripod I haven’t got different exposures from the same angle. And I don’t have Photoshop – yet.