In last month's Question of the Month I discussed using the computer to solve the problem of extreme exposure values within an image. However, to solve that problem one must also know how to meter the correct areas in the first place. Today's cameras and digital cameras offer incredibly accurate metering systems, and usually matrix or evaluative metering (Nikon's and Canon's terms for full-screen metering) works remarkably well. For that reason, many photographers simply put their camera on evaluative metering, aperture (or shutter) priority mode, and fire away. Most of the time, the shots that result look fine.
But there is a flaw in relying solely upon matrix or evaluative and simply letting the camera make settings. Recently, on our Kenya trip I observed folks shooting dark subjects in deep shade against bright, sunlit backgrounds, just firing away without any awareness that:although the camera on an aperture or shutter priority mode on evaluative (or matrix) metering would give a shutter/aperture combo that would 'zero' the meter -- indicating a 'correct' exposure, the contrast range present within the scene insured that a good image would not be produced.
Let me expound on this to stress this point. When you simply 'point and shoot,' no matter how sophisticated the camera -- an F5, a EOS1v, whatever, the camera will always give a 'zeroed' exposure, indicating that all is well. Of course, you can auto or manually bracket around that exposure, and that might produce an alternative result that works. However, as my friend on safari illustrated, relying solely on PS methods sometimes cripples the thinking process -- and a good photographer may be lulled into thinking every shot will come out OK because he or she does not recognize the extremes in exposure values that are present. I can't tell you how often I've heard, 'well, I hope it comes out' when, in fact, you should be extremely confident that your exposures are correct and that the images will come out!
Writing this, I'm not dismissing evaluative or matrix metering and the auto modes. I'd bet that 90% of the time the shots are right-on or within 1/3rd of a stop of what I'd use using my method. However, these modes cannot recognize image-ruining contrasty situations. Each shot, unless bracketed, is zeroed to what the camera thinks is best, and it may not be. In fact, sometimes the range in contrast is so great that nothing can be done short of recomposing to eliminate the contrast range, or using fill flash, or some other method to reduce the contrast. But unless you recognize these limitations, and the PS method lulls and tempts and eventually seduces even the best shooters I know, you're quite likely to blow great shots because the camera computes the wrong answer.
Contrast can kill a shot, because it can so trick an exposure meter. Conversely, contrast can enhance an image by emphasizing or capitalizing on the dramatic lighting inherent in a contrasty scene. Bracketing such images might work -- and waste film, but isn't there a better way to insure great shots?
Welcome to spot metering, manual mode. Most of the serious professional wildlife photographers I know (and there are some successful and notable exceptions, to be sure) use this method. Doing so, one meters the tonality one wishes to base an exposure upon. Perhaps just as important, using spot metering gives one an awareness of what can sometimes be extreme differences in exposure value in a scene. On PS modes, that difference is rarely evident, as exposures are so 'averaged' that rather radical compositional shifts must be made to seem a significant change in a meter reading. Indeed, many of the students we teach have grown so accustomed to PS mode that they don't even look at the shutter speed and aperture displays, are not aware when they change, and do not recognize the importance of any changes. That's scare.
What was especially gratifying for me on our recent Kenya-Tanzania trips was seeing how most of the graduates of our Complete Nature Photo Course handled exposure. With perhaps one exception, all were using manual mode, spot metering. I asked a few whether they were using evaluative/aperture mode and they looked at me like I was crazy -- you taught us spot metering, why would we switch? -- was the general gist of the comments I received. So, how would I expose for these images?
Both
of these images exhibit a lot of contrast. In the lioness image
the light areas probably are greater than the dark areas, but
with the Gaucho the dark areas predominate. PS methods might yield
an OK exposure on the lioness -- although there might be a bit
too much weight given to the dark side of the lioness, resulting
in an exposure that would be slightly overexposed. With the Gaucho,
PS methods probably wouldn't work, as the dark areas predominate,
and the light area is predominantly in the upper right of the
image. So, what did I do?
For the lioness, I spot metered the flank of the lioness. Leaving
the settings at the metered value would have produced a middle-tone
coat but the lioness's coat glowed in the side-light/back-light
situation. Opening up about 2/3rds of a stop lightened the coat,
and also 'opened up' a bit of the shadowed detail that would otherwise
be lost.
For the gaucho, I simply metered the non-shiny area of skin on
the man's face (right below his left eye, i.e. the eye/cheek on
the right side of the image) was my base middle tone value. I
was careful not to meter the specular highlights -- the shiny
skin, since these would underexpose the image. Remember (if you
knew), metering white makes white gray, and metering a shiny white
area would do likewise, darkening the entire image.
Sunsets
may trick PS methods. In the image on the left, the bright sun
could bias the exposure as the camera tries to make the sun middle-tone.
If it did, the tree would be lost against an almost black sky.
I metered the sky to the right of the tree trunk, then metered
the sky a bit above the topmost branches, and compared values.
The area right around the sun can be so bright that the sky at
the top of the tree branches could be several stops less, and,
if so, the tree branch silhouettes would merge with the dark sky.
Letting that area of the sky go about 1 stop underexposed and
the area to the right of the trunk meter middle tone (zeroed)
gave me the correct exposure. The sun, being so bright, just burns
out bright and that's OK.
For the giraffe silhouette I purposefully framed in this way to
illustrate several points. If you were in the field with me, you
would have seen objects and details in the area below the giraffe's
legs. Although you cannot see it in this image, there could have
been a herd of zebras or gnus or a pride of lions -- you can't
see them (they weren't there) because the exposure differences
between the bright sky and the foreground is just too great. With
PS methods the camera, based on an almost 50-50 composition, would
try to bring some detail to the foreground by 'opening up' and
by doing so the bright sky would be 'blown out' or overexposed.
With PS methods, you get a 'zeroed' exposure, and you might compose
thinking that the foreground critters are going to show up, too.
They won't, unless the sky is hopelessly overexposed.
I simply spot metered the pinkish/mauve area of the sky and went
with that exposure. This gave the sky a middle tone look, a somber
look, but I liked that. Had I wished, I could have overexposed
that area of the sky by 1 stop to brighten up the sky and give
it a translucent look, but this could have required using a slower
shutter speed and may have produced blur as the giraffes were
walking rapidly.
The
fox? I spot metered the orange fur. Alternatively I simply could
have relied on Sunny 16 - 1, as the image was made under Sunny
16 conditions but was side-lighted, which reduces the exposure
by 1 stop.
The Lion? Backlighted subjects often look most realistic when
they're slightly darker than a zeroed, middle tone exposure. I
metered the cat and underexposed by 1 stop. The backlighted fur
still glowed brightly as the light passing through the translucent
hair was far brighter than the opaque lion.
All of these techniques are taught, in depth, in our Complete Nature Photo Course, here at Hoot Hollow each summer. If you're interested in learning more, check out the brochure.