Thursday, January 18, 2007

Low light, high ISO

click photo to enlarge
For most of the year my camera is permanently set to ISO 100. My reasoning for this is as follows. I have a good camera with good lenses capable of resolving images well. I usually take a fair amount of care with my photographic compositions. All of my images are shot in RAW to allow the greatest flexibility in post-processing. So, why would I unneccesarily raise the ISO and introduce the image degradation that this entails?

However, there are a few occasions when I do increase the ISO. On dull winter days, typically between mid-November and the end of January I sometimes set the camera to ISO 200 and leave it at that for all my shots. Indoors, when taking family snaps, I sometimes use ISO 200 or even 400 rather than flash. And, when using a long focal length lens on darker days those same settings are useful. But, I've never used my present camera at a higher ISO setting than 400 - until a fortnight ago. I was coming to the end of a longish walk that had taken me inland and then along the shore between St Anne's and Lytham in Lancashire, when I saw this man, with his rucksack and his dogs. In the tinted light of dusk he was outlined against the water of the Ribble estuary. Southport's gasholder and buildings were dimly silhouetted beyond, and above the gulls were gliding down to their night-time roost. I could see that the man would soon run out of sand, turn away from the water's edge, and head up to the promenade. So if there was a shot to be had, I had to be quick! With no time to set up the tripod, I turned the camera to ISO 800 and fired off a few shots, more in hope than expectation.

The resulting images had visible noise, and in my haste I had underexposed too much, increasing the effect. But, some heavy post processing has produced, if not a great shot, then one that is passable, and that captures the atmosphere and empty space of the estuary at dusk. I used a long zoom lens at 268mm (35mm equivalent), with the camera set to Aperture Priority (f6.3 at 1/200 sec), ISO 800 and -0.7EV.
photograph & text (c) T. Boughen