Exposure Part VI - Bringing all it together

20 May, 2007

In the final part of my short guide to exposure, I bring the whole process together and examine the thought processes I went through in a number of real field situations.

I follow the same routine to evaluate the exposure for each image I make. In each case, I am looking to select one reference point to use as a base for metering – either a midpoint, a highlight or a shadow.

Here is the process:

  1. Identify a mid point exposure - either by spot metering (most scenes) or using an incident reading (macro or closer in scenes).
  2. Find the brightest point and check that it is in the range of the film or sensor. If it is not decide whether to meter for the highlights , add a graduated filter or switch to a higher latitude film.
  3. Check where the shadows fall and decide if you want to meter for the shadows or not
  4. Make the final adjustments for filters and (on large format) bellows factor, if necessary
  5. Re check your exposure just prior to pressing the shutter (because light changes and our eye doesn’t always notice)

Here are some real examples to illustrate the process.

'Holding Out'

For the green fern, I used an incident reading to get an accurate exposure. Using a quick disk indicated that +1.3 stops was necessary to account for bellows factor.

'Rowan Tree Falls'

The primary risk in this scene was not retaining sufficient detail in the water. Having started with a spot meter reading on the grass (cross checked with an incident reading), I checked the highlights. It was on the edge of the film (velvia), about +1.7 above the mid point. So I chose the water highlights as the reference point to be safe. (I metered from the highlights and added +1.7 stops.)

'Dawn over Loch Cleat'

This scene was going to need a graduated filter to expose successfully for transparency film (Velvia). Comparing the midpoint (spot reading off the grass) and the highlights in the sky, a two stop grad placed the highlights within range of the film. Having positioned the filter, I waited until the sun came. As soon as it did, I spot read off the sunlit grass on the mountain side and exposed for that.

'Icicles'

In this final icicle scene, I was determined to retain shadow detail. I metered for the shadow area and reduced the exposure by -2.7 (for provia film).

© Jon Brock 2007