Sometimes your exposure time is determined, not by technical or aesthetic requirements, but by nature.
I had just finished photographing Dawn Sentinel when something caught my eye. At the bottom of a cove, a few hundred metres away, shining like a beacon, was this slab of rock. Naturally I couldn't see any details, but I could see the potential so I packed as quickly as possible and made haste along the cliff top, searching for a way down.
Before long I found a Pandanus-filled gully and executed a semi-controlled, on-the-bum, slide down the gully, emerging just a few metres from the rock.
The bottom of the cove was totally in shade, while the far cliff was bathed in light. The slab reflected the light from the cliff, this is what gave the contrast to the scene. However the sun was gaining height rapidly and the effect would vanish before long.
Setting up the camera to take the photo I realised why the rock remained so wet. A wave broke nearby, swamping my feet and the rock and drenching the camera with spray. This would complicate matters.
I use a change bag as a focusing cloth and, in situations like this, I drape the change bag over the camera to protect it. For this photo I would only be able look through the camera to check composition, depth of field etc. during the periods between waves.
Normally I use a combination of camera movements and a small aperture to obtain maximum depth of field. The trade-off being a very long exposure. I realised that this would not be an option here because I didn't want a wave intruding during the actual exposure.
I would have to time the waves to find the longest time between them, this would determine my exposure. I did this and decided that they occurred every 13 seconds so I selected an exposure time of ten seconds and exposed two negatives.
With one photo "in the bag" I did what I should have done in the first place. Thought about the image.
In the rush to get a shot I had lined up on the first composition that looked reasonable. The trouble is I had totally missed what attracted me to the scene in the first place; the bright reflection from the slab.
Let's try again.
Changing the camera's position slightly moved the reflection from a narrow band on the slab's leading edge to a full-on glow covering the entire top. That's better.
Now let's think about colour. Remember that the slab and its surroundings are totally in the shade, in predominately blue light. The reflection however is coming from a rock face bathed in bright sunlight, this light is yellow in nature. An orange filter will increase the contrast between the two by blocking much more of the blue light than the yellow.
I added an orange filter, adjusted my
exposure by two stops to allow for the light adsorbed by the filter,
Returning to base I dismantled
the camera, washed off the salt water and dried the parts in the sun.
This is one of the beauties of a simple camera, it is almost unaffected
by nasties like salt water and can largely be fixed in the field with
simple tools. Of course the same does not apply to lenses, I try to
be more careful with them.