Spot Metering for expressive exposure.
Passing Rain, Sgeir Liath.
One subject that crops up time and time again when I'm tutoring is correct exposure. Before I explain my work-flow regarding this I would say that, rather like composition, exposure can be subjective and any rules that apply can (and should) be broken if you wish to develop your own vision. The classic mistake I encounter is when people spend ages hunting for a mid-tone around which to build a tone map of a scene. When in Gairloch back in February a client on the tour stood for about twenty minutes trying to fathom the relationship of tones in the scene and struggled to choose a mid tone, eventually the fantastic pool in the middle ground drained of water as the tide went out and the composition no longer worked. I had come over to help and found the ideal exposure in just a few seconds using my trusty Pentax Digital Spot-meter. Not by looking for a mid-tone but by quickly deciding how I wanted a certain detail in the foreground to look (be it a highlight, shadow or other tone) and working from there.
As an easy illustration I shall use this Sgeir Liath image which was made in fast changing (and falling) light on a breezy Summers evening just twenty minutes walk from home. Wishing to capture the passing shower I had no more than five minutes to set up, focus, meter, grad and shoot just the one sheet of film. Any doubts about exposure and I would have missed the opportunity.
Rather than waste any valuable time trying to ascertain what could be a mid tone in this scene I simply looked for something with an absolute value to me, something in the foreground that I would always assign a value to based on how I choose to expose transparency film (for which this illustration applies). In this case it was obvious, not the darkest patches of sea weed along the very edge of the shore but the whitest patch of lichen on the rock. I always expose white to be one and two third stops brighter than a mid-tone (assuming I wish to record textural detail as well as colour) so having metered the white with a ev reading of 9 and 2/3rds ( 1 second @ f16 2/3rds if you prefer apertures). This meant that the ideal mid-tone for my lichens to appear white was ev8 giving me an exposure time of 4 seconds @ f22. Now to quickly ensure that everything in my foreground could be held in the four stops that Velvia allows by metering highlights and shadows elsewhere ( note foreground only). Yes, everything holds, time taken so far=10 seconds. Now for the sky and whether I can hold it with grads and make this invisible. So I go straight to the darkest part of the cloud with the intention of bringing this back to my chosen midtone ( ev8, 1s @ f11). Here the value of the darkest part of the cloud was ev10 which basically meant that two stops of nd were needed to get back to ev8. In this instance I used two, 0.3 (1 stop) grads as I also had to control the reflecting water between the rocks. These were applied diagonally with one right down to the seaweed and the other higher and only really covering the sky. The resulting image has a very natural feel with the colour in the sky, water and rock perfectly balanced. The whole process of metering and filtering took less than a minute.
So, what other tones do I base my exposures on? Firstly I learned fairly early on that sunlit grass is a mid-tone but I made the stupid mistake of exposing it so in a wider scene. Being 18% grey doesn't mean it has to be recorded that way, I prefer to record sunlit (lawn) grass a third of a stop brighter than mid to portray the correct mood (for me). Don't forget that grass comes in a multitude of colours and tonal values. Bleached, yellow or white grass will clearly need to be exposed brighter than a mid tone, usually one to one and a third stops brighter. If there is bleached grass in your foreground there's a good place to start your metering. Sunlit snow will normally be one and two thirds above mid for obvious reasons, snow in the shade makes a reliable mid tone as would white paint in the shade, check if you have both in the scene and you can choose which to base your whole exposure on.
Through experience I now build all my exposures based on what tone I assign to an important colour that is usually in my foreground.
White with detail 1 and 2/3rds over mid.
Yellow 1 over mid
Pink 1 over mid
Edges of (unlit) moss covered rocks 3rd over mid
Post Box Red/Lawn Green mid tone, plus or minus a 3rd for expression
Maroon/Chestnut Brown 1 below mid
Black with detail 2 below mid
Afterburn, Torridon.
My recent images made among the burnt pines in Glen Torridon basically had two easy reference points on which to build an exposure, yellow grasses and black charred wood. In that instance however I opted to work from the grasses as they presented me with a more uniform mass of colour. Burnt timber can contain lots of tones as it can take on a silvery sheen and therefore become reflective in which case it could give misleading readings that would be likely to result in an underexposed image.
While I still make the odd mistake with my metering due to lack of concentration or sometimes very complex scenes I would say that 95% of my A sheets are now accurately exposed and I rarely push or pull any processes to compensate for poor exposure.