Exposure and Tonal Contrast
Correct Exposure is combination of Shutter Speed, Aperture and ISO and a creatively correct exposure is combination of all of above and the photographer’s creative mind. I believe there is nothing can be termed as bad or good light for my exposure, it should be appropriate light as well as exposure. Lighting depends on Seasons, Weather, and Time of the day. The essential qualities of light are direction, color and intensity. I have often realized that waiting for the perfect moment and animal behavior is often the difference between a good image and a great one (Alas, I don’t have any yet). I like the term tonal contrast, which is nothing but the range of highlights and shadows. An Image with high level of tonal contrast, challenges me, if expose for highlight I loose the details in shadows; if I expose for shadows then I end up with brunt out Images.
Front Lit Subjects:
I always meter from the subject, preferably spot metering and compensate the exposure using 18% mid-grey rule. But Front lighting eradicates shadows, provides even illumination, and makes the exposure setting relatively easy for me. Overcast front lighting eliminates the tonal contrast problems that a sunny day creates in areas with lot of tonal variances. I would happily trigger the camera shutter with an evaluative meter in those kind situations. This kind of light helps us to take nice images of high contrast subject such as Zebra. In both the cases in don’t forget to garnish the Image with little bit of fill in flash.
Back lit Subjects:
Again I prefer spot metering, one of my favorite lighting conditions as these kind of lighting provides me a scope for representing the subject as graphical or atmospheric object depending upon exposure. I set the exposure for highlights to render the subject in silhouette, expose for shadow to create wonderful halo of light around the subject. I am very careful about metering when using telephoto lens in back lit conditions. Since telephoto lenses increase the image magnification of very bright background, the light meter sees this magnified brightness and suggests an exposure accordingly. May be taking exposure from a neutral area will help. For example, taking exposure from the bright sky to right or left of the sun might help if it’s outdoor. Yes, I can use flash if I don’t want to take silhouette but whenever I see the sun on the horizon, I couldn’t control myself to take a silhouette or halo.
Side lit subjects:
We need highlights and shadows to create illusion of three dimensionality in our two dimensional Images. Side lighting provides that as well as it emphasizes texture, and shows volume and depth. The Images never looks flat and dull, because of the tonal variances that are shadows, contrast and color (when subjects are bathed in a glorious illumination of early morning and late afternoon). Again I depend on Spot metering.
If the tonal variance is high, let say the light is falling on one side of the subject and the other is in shadow. I always expose for the highlights, I will swear by Spot metering. Then I will compensate the exposure using the golden rule of 18% mid grey although I will be careful not to lose any of the details on the highlighted area. Then pop required flash to illuminate the shadow area. If required, I will use raw processing tool to fill in light and recovery etc. Sometimes, its okay to lose some details if that is not very significant, let’s say I am composing an Image of a lion whose only an ear is which burring out. I would not expose for this as, I have discovered the rest of the Image. I will expose for the appropriately illuminated face and use fill in flash, if required.
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Photo credits: Arindom Chowdhury.