Another kind of exploration is over an extended period of time. Ansel Adams wrote, in relation to his chosen field, landscapes, "Repeated returns may be more rewarding than prolonged waiting for something to happen at a given spot." This clearly makes more sense in the photography of place than most other subjects, but it brings with it a new set of issues and expectations. With a landscape, what the photographer expects to have changed is the lighting in the short term, and perhaps seasonal variations over a few months. But the unexpected becomes more likely as time goes by and as more of the hand of man is evident. The exploration of one subject over a period of time takes on a very different form from the single-session exploration that we began with. In addition to unpredictable changes that might include demolition and new construction in the manmade landscape, we should also factor in our own changing attitudes. What appeals to a photographer at one point in time might at a later date seem boring.

There is considerable risk in actually relying on a return to deliver an improvement, not least because the combination of things that first attracted a photographer's attention with the possibility of making an image can be quite a subtle mix, and may simply not be there at another time. This is especially true when unpredictable lighting is involved. Actually relying on a return visit to produce results is out of the question, which is...