Digital Focusing Part Two

By: Gary Ferguson
In the first part of this article we looked at how badly image quality was degraded by any shift from the plane of precise focus, and the way that historic concepts of depth of field are inappropriate if enlarging to the capacity of today’s inkjet printers. So if stopping down only delivers limited benefits are there any alternative solutions?
Well, there are at least three focusing strategies that don’t revolve around the traditional notion of extending depth of field with smaller apertures.
Infinity Focus
When we’re confronted with a scene that demands near-to-far sharpness most of us instinctively bias the depth of field in favour of the foreground. The rationale being that the far distance tends to be a bit soft anyway, so the eye won’t object if we make it a bit softer still. For many compositions it’s a strategy that makes sense, especially when the background only serves to give context to a dominant foreground object. For example a popular subject for British...