Saturday, June 29, 2013

More on Exposure: how to fix common exposure problems in your photography

The second article in an occasional series aimed at beginners called “Things Experts Forgot to Tell You” or “Things that You Forgot you had to Learn” was All about Exposure.  (The first article is Why Won’t My Lens Focus?) This post expands on the ideas presented in that article with some real life examples of exposure problems and how to overcome them.

I recently returned from a trip to the Pacific Northwest and Alaska. One of the major exposure problems that I encountered was white, featureless skies due the fog, mist, and overcast clouds common in the region. There are a few different options for dealing with such a problem, and I will present a few examples to explain them each, below.

AE Lock

In All about Exposure I explained some of the benefits of the AE Lock button and how you can use it to override your camera’s suggestions about what the correct exposure might be for a given situation. I found myself using the AE Lock button quite frequently at Mount Rainier to force the camera to balance the darker colors and tones of the trees, rocks, and landscape against the overwhelming brightness of the overcast skies.

The images above show the impact of using AE Lock. The image on the left was the camera’s suggestion for the correct exposure, based on evaluative metering: ISO 100 (set by me), an aperture of f/5.6, and a shutter speed of1/80th. For the image on the right, I pointed the camera up at the nearly blank sky, pressed the AE Lock button, and then recomposed the image, which resulted in an exposure of ISO 100, an aperture of f/8, and a shutter speed of 1/160th. The second image is deliberately underexposed, according to the camera, but far better represented the colors and tones before me, in my opinion. It also brought more definition and detail to the sky.

Troubleshooting Your Exposure | Boost Your Photography

The brightness of the sky can impact an image even when you don’t think of the sky as being in the picture, as in the two images above. Here, the brightness of the sky is evident in the light filtering through the trees and the shadows on the path. The camera chose the exposure on the left: ISO 100 (set by me), an aperture of f/3.5, and a shutter speed of 1/13th, while I used the AE Lock (again, pointed up more towards the sky then recomposed) for an aperture of f/3.5 and a shutter speed of 1/20th. This slight underexposure led to better colors and depth to the overall image (as did slightly adjusting the composition to ensure a straight horizon line and vertical trees).

Recompose

Another option to fix exposure problems is to reconsider the composition of your image. If a featureless sky forms too large of a portion of your image, it may be impossible to properly balance it out for a correctly exposed image.

Tunnel at Mount Rainier - note the white sky

In the image above, I wanted to focus on the tunnel, but while I was happy with the colors and details through and inside the tunnel itself, the sky above got ‘blown out.’ (Blown out is a term that photographers use when a picture or area of a picture becomes so overexposed that it becomes completely white and loses any detail that might have been there.) If I used AE Lock and exposed for the sky, the resulting darker image would lose the colors and details in and through the tunnel that I wanted.

Tunnel at Mount Rainier by Archaeofrog on Flickr

The solution here was to rethink and then recompose the image. I knew that I wanted to feature the tunnel, both inside and outside, so I decided to recompose the image to completely exclude the sky. Then it became much easier to balance the light and tones before, inside, and through the tunnel.

Bracketing

The method and ‘how to’ part of exposure bracketing was covered in the All about Exposure article. Bracketing is a particularly useful technique in the field when you are unsure about an exposure or want to capture a range of different exposure options.

I know that the LED screen on the back of my camera is merely a compressed snapshot and not a perfectly accurate representation of the image that I have captured. In general, I have found that images that I might think look ‘too dark’ on the LED screen look perfectly exposed when I download and examine at them on my computer monitor. The LED screen is also difficult to see in bright sunlight, and I often don’t think about how my wearing sunglasses while looking at it may impact how I interpret an image. Thus, when I find myself in a situation where it is difficult to determine the correct exposure, I often rely on bracketing and make the decision later, in front of my computer.

For much of our time at Rainier, we were unable to see the mountain itself, due to the fog, mist, and clouds, but I still wanted to capture images of the bits of the mountains that were visible. Determining the exposure was difficult, due to the brightness of the sky, the darkness of the trees, and the variable nature of the mountain, so I decided to use exposure bracketing.

Bracketing. View towards the mountains at Mount Rainier by Archaeofrog on Flickr

This set of three images, bracketed at plus-and-minus one stop on the exposure compensation scale, demonstrate a range of exposures for the same image. In this case, I liked the definition of the mountain and the blue sky in the middle image (underexposed), even though it rendered the surrounding pine trees as fairly dark and a bit featureless.

Fixing Exposure Problems in your Photography

The key to finding and fixing exposure problems in the field is knowing what you are trying to accomplish in each image and using workaround techniques, as needed, to meet your goal. If a bright sky or overcast day is making your images appear too bright or blown out, use AE Lock to take a reading from the sky, recompose your image, and see if you get a result that is closer to your liking. Or, if you can, change the composition of your image to exclude the sky entirely and eliminate it as a factor. Or, give yourself a buffer by using exposure bracketing to capture a range of different exposures for the same composition and choose the best at a later date. Each of these methods gives you more control over your images and their exposure and will help you come home with the images you desire.

Want more posts like this one? Click 'For Beginners' up at the top or try the rest of our series, Camera Settings and Strategies:




Want to learn more? Boost Your Photography: Learn Your DSLR is now available from Amazon. Get the most out of your camera with practical advice about the technical and creative aspects of DSLR photography that will have you taking beautiful pictures right away.
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