exposure compensation in wildlife photography

Exposure compensation: Don’t Blow Up Your Gulls

WILDLIFE PHOTOGRAPHY TIPS #1

Originally published in The Blue Bill – the quarterly journal of the Kingston Field Naturalists

I am not an expert photographer and this post is not intended for experts. I became interested in wildlife photography when I was planning a trip to Tanzania in 2015. It was likely to be a once-in-a-lifetime trip and I wanted to come back with some good wildlife photos. So I obtained a decent camera and lens and took a short photography course before we left. The results were encouraging, and I could see that with more knowledge and experience I ought to be able to capture even better images.

In a way photography is like birding: the is an infinite amount of information, so there is always something new to learn. And like birding, photography rewards both study and practice. Through trial and error I have learned a fair amount about the craft of photography over the last few years. This post is intended to share things I have learned on my journey that may be of use to other aspiring photographers.

Understanding Exposure Compensation

In this first installment I want to talk about exposure compensation. It’s a camera function that many amateur nature photographers I have met seem unaware of, but in certain situations it is a really important tool to ensure you get the image you want.

I won’t get into a long explanation of how camera light metering systems work. Suffice it to say that most of the time they work very well. But there are a few situations in wildlife photography where left to its own devices the camera will make the wrong decision. Knowledge of how to compensate for this will help you get the right exposure and avoid disappointment. Those situations are:

  • Backlighting
  • Shadow
  • Wetness and Whiteness

Backlighting

Let’s start with a common situation: birds up in the treetops, or in the case, a bird on a wire. You see a Mourning Dove; your camera sees a mostly light background with one dark object. So it averages out the exposure and you are left with something like the image in photo 1 – a dark blob. After I took the first image I adjusted the exposure compensation two steps to the left (to -0.7) and photo 2 was the result. The bird is correctly exposed and all its plumage details are visible (e.g. the thin blue eye ring).

Of course I could have adjusted the exposure of photo 1 in post-processing, but the best-looking images start with a file that is correctly exposed in the first place. This is particularly important if, like most photographers, you shoot in a lossy format such as JPEG. Each time you edit a JPEG file more data is lost, so the closer you get to correct exposure in the first place, the better your final image will look.[1]

Shadow

Metering systems also struggle to correctly expose objects in shadow. Photo 3 shows a pair of Hadada Ibis from that trip to Tanzania. The birds are underexposed because they are in shadow and there is bright sunlight on the right side of the image. The metering system tried to average out the exposure, which left the birds in the dark. In this case positive exposure compensation – moving the exposure one or two steps to the right – would have produced a better image (photo 4).

Wetness and Whiteness

Bright spots also cause trouble for the metering system. In wildlife photography this often shows up when photographing in bright sunlight. Anything white or wet can end up being overexposed even if the rest of the exposure is good. So gulls, terns and white pelicans are a problem, and so too are turtles and frogs when the sun is shining on their shells or skin.

In the case of bright spots, the issue is that the image may look properly exposed, but on closer examination the highlights are blown out. Blowing out, also known as clipping, happens where the intensity of light in a certain area exceeds the camera’s ability to capture information. So a blown highlight may look white, but if you look closely you will see that there is no detail in that part of the image.

Consider photo 5 – a Ring-billed Gull in sunlight. The image looks properly exposed, but if you zoom in (photo 6) you will see that there is no feather detail – it’s just a blank field of white. Sadly, blown highlights are on thing that cannot be corrected in post-processing, as there is no data to work with.

Here again, exposure compensation comes to the rescue. In photo 7 I deliberately underexposed the image by adjusting exposure compensation two steps to the left (-0.7). In post-processing I was able to increase the exposure so the gull is properly exposed, but as a blow-up shows (photo 8) the plumage details in the white area are fully visible.

Using Exposure Compensation

If you want to experiment with exposure compensation, the first step is to find how to adjust exposures on your camera. I recommend reading the relevant section of the manual, which will show you where the adjustments are made. On most DSLR camera bodies you will find a button that looks like photo 9. On bridge cameras, it is more likely to be a multi-function button. Typically you will need to hold down this button while moving one of the rotating dials or switches to adjust exposure up or down. In either case you will be able to see your adjustments on the exposure compensation slider, which is usually visible in your camera viewfinder.

Photo 9

Three Important Tips

1. The monitor (LCD viewscreen) on the back of your camera allows you to test and adjust. So when you come across your quarry and the lighting may be problematic (backlit, shadow, wet or white) take a photo to start off, then if the bird or beast stays around, look at your monitor to see if the exposure is good. If not, try an adjustment of two steps, reshoot, and check the monitor. Continue testing and adjusting until you either get the perfect exposure, or more likely, the bird of beast absconds.

2. Most cameras have a function that will show blown highlights in the monitor. For Nikon cameras it is cunningly named Highlight Display. Again, check your camera manual to see how to activate this function. When activated, if you take an image and look at the monitor you will see flashing lights (photographers call these “blinkies”) in areas where there are blown highlights. This quick check will let you know whether you need to adjust the exposure. Note that for backlit objects, if the object itself is correctly exposed there will probably be blown highlights in the sky behind it. This is not really a problem other than the fact that the sky tends to end up white rather than blue.

3. In most cases your camera will not automatically default back to the zero position once you have taken an image. I won’t tell you how many times I have forgotten to take account of this and taken a quick snap of a rapidly-departing bird only to find that exposure compensation was set for shadows and the image was mostly blown out. It seems that the rarer the bird, the more likely it is that this happens!  So you will want to keep exposure compensation in mind as part of your mental checklist.

Happy photography!


[1] Wikipedia has a good article on JPEG. See the section entitled Typical Usage at https://en.wikipedia.org/wiki/JPEG

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