Bob Grier’s From the West: Digital Exposures-Problem Solved.

Snake River and extreme contrasts

Returning somewhat to the subject of my last blog, photographing during the contrasty lighting of over head-sunlight, here is an example from yesterday. The Snake River image here is very contrasty, brilliant whites — back-lit white water and deep, dark shadows. Again, I’m amazed at the contrast range that can be captured by the digital sensor. This is a “straight-forward” image, without PhotoShop, the white balance and a few other tweaks performed in LightRoom’s develop module.

The camera was a DSLR, a larger, high megapixel interchangeable lens camera with a 35mm moderate wide angle lens. I started out trying a few test exposures, setting the camera to a slow shutter speed, hoping there would be some “movement” of the water but without resorting to placing the camera on a tripod. While relying on another digital camera wonder, in-camera image stabilization to keep camera movement from ruining the photo handheld at a slow 1/25-th of a second shutter setting.

What I’m trying to say — this was a very quick shot taken while walking around, looking at quite a few different compositions through the lens.

If your digital camera has a viewable “histogram” to help you understand the exposure process, here is how it works. (Unfortunately, I’m not able to “draw” a histogram here to help explain it). Basically, the histogram window shows a bar graph of that specific exposure, the high values or brightest parts of the image to the right of the histogram window, the darkest areas represented by the bar graph’s lines on the left side of the histogram.

Most digital tutorials available on the internet usually talk about “Expose to the Right” or ETTR. When I looked at an earlier test exposure taken at the shutter priority mode where the camera sets the aperture or f-stop to go along with the shutter speed I’d selected — the histogram’s “bar graph”, appeared like a “bell curve”, appearing in middle of the histogram window. I tried the expose to the right fine tuning, turning the camera’s exposure mode to Manual and very slightly increased the exposure for this image. Some cameras warn the photographer by “blinking” in high light and low tones in the review image indicating both over and under exposed areas. The very brightest bubbling water in the center of the image was blinking in this example’s, review and histogram, but a few small tweeks in the post processing produced the balanced exposure captured here.

For more information on ETTR, a good tutorial site like www.luminous-landscape.com can help you understand and use the camera’s histogram features.

Another advantage to ETTR is that the very slight increase in exposure has a dramatic impact on the amount of digital noise (think film grain here) in the shadow areas, producing a cleaner final image, especially for larger prints.

Sorry for all the geek talk, but since I’d mentioned it earlier I thought those of you that enjoy digital photograph might be looking for a clue to my rants and raves. Another lesson to be learned here is the very high percentage of your photographs that the camera is able to accurately expose without the photographer’s involvement. The camera’s automatic exposure system’s photograph could be post processed as well to an image that could look nearly as good as this one. Spending a few minutes on digital exposure tutorials and your camera’s instruction booklet is always a good idea. Especially if you run into extreme contrast situations.

Bob