Updated: Jun 29
Here’s the challenge: you’re shooting wildflowers in deep shade, but your composition includes peaks bathed in sunrise or sunset light. The difference in exposure between highlights and shadows is too great for your sensor to straddle comfortably. HDR might be an option, but there’s a breeze blowing and the flowers only come to a complete stop for a fraction of a second before starting to sway again. Merging three bracketed frames into a single HDR image is likely to produce “ghosting,” a highly unnatural effect where the image shows two semi-transparent versions of the same flower that are not in perfect alignment. Sure, you could use the deghosting feature in your HDR software, but that doesn’t always work. In some situations, there’s a better way.
The Rembrandt Solution is my name for a different approach to photographing in high-contrast light. It involves shooting two frames using exactly the same composition, one correctly exposed for the highlights, the other correctly exposed for the shadows, then blending the two images in Photoshop. The virtue of this approach is that the part of the image containing flowers will all come from one frame. This eliminates ghosting. An additional virtue is that each image will be exposed fairly close to mid-tone, which means each image will have good local contrast. Blend those two images in a believable way, and you’ll have a very natural-looking rendition of a high-contrast scene.
The crux of this technique is determining the correct exposure for each image. In the past I used a hand-held spot-meter to calculate the correct exposure for the highlights and shadows. While this is certainly a viable approach, it requires lots of practice to get it right quickly and consistently, and it requires buying and carrying yet another piece of equipment. Today I recommend a different approach.
Start by putting your camera in manual exposure mode. Next, turn on Live View, and cycle through the various displays until the histogram is displayed. Set the aperture you need to achieve the depth of field you want, then start adjusting the shutter speed while watching the histogram. Ignore the left (shadow) side of the graph. Right now you’re only concerned with the highlights. Keep adjusting the shutter speed until the highlights are almost but not quite clipped, as shown in figure 1. You’ve just determined the correct exposure for the good-highlights image.
Now begin lengthening the shutter speed, one click of the adjustment wheel at a time, counting clicks as you go. Watch the shadow data on the histogram data move slowly to the right. Ignore the highlights, which will probably become clipped. Stop when the shadows have moved comfortably away from the left edge of the histogram, as shown in figure 2. They don’t need to be dead-center. You’ve now set the correct exposure for the good-shadows image. Leave this exposure set on the camera.
By counting clicks you have determined the difference between the good-highlight exposure and the good-shadow exposure. On most cameras, one click equals one-third of a stop. If you changed the shutter speed by six clicks, the difference is two stops. Turn on auto-exposure bracketing. If possible, set the number of frames in the bracket set to two. Don’t worry if you can only shoot a three-frame bracket set. You’ll end up with one highly overexposed frame, which you can discard. If necessary, set the bracket order to metered, under, over (which is the default for most cameras). Now set the bracket interval, the difference in exposure between frames, to the same value you calculated as the difference in exposure between the good-highlight and good-shadow frames. In this example, the difference is two stops. Be sure the second frame is set to minus exposure compensation, not plus. As a practical matter, the difference will almost always be between two and three stops. If you calculate a four-stop difference, you’re in an HDR situation. Finally, set the drive mode to continuous high.
Wait for the wind to stop, and fire away. The first frame will be perfectly exposed for the shadowed flowers, as shown in figure 3. The second frame will be perfectly exposed for the bright mountains in the background, as shown in figure 4. I discuss the best procedure for combining these two frames in Photoshop in this blog post.
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