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Chapter Six: Controlling the Light

Go Too Far—On Purpose

This is a quick test for comparing your in-camera highlight warnings to your raw files. The camera’s highlight clipping alert appears when the camera detects any white without detail.

There are two general ideas at work:

• Diffuse highlight detail clipping is when something that normally would—and should—have tone is missing all or part of its detail, i.e., an exterior white wall of a house that’s been overexposed. This type of clipping is easily controlled through in-camera exposure settings and post-processing highlight recovery tools.
• Specular highlight clipping is a little different. A good example of it is the reflection of the sun in a chrome bumper, which will always cause clipping. The exposure value difference of the sun compared to everything else around it is huge. It’s good to be aware of specular highlights and to try and minimize their existence in your images, but if they’re present, you won’t be able to control them through exposure.

Set Up

1. Find the Picture Styles menu and change it to Neutral, -2 on Contrast and -2 on Saturation. ¹ This will make your in-camera histograms more like your raw files.
2. Turn on your camera’s highlight warning.

Shoot

1. Choose a scene that has a wide range of tones, preferably something difficult, like noontime sun with very dark shadows and a bright sky. Bright, specular highlights are also good for this exercise. Look for sunlight reflecting off metal or glass.
2. Set the camera at a middle aperture (like ƒ/8) and take a meter reading, then balance the ISO and shutter speed to get a good normal value. Use a tripod, or choose an ISO that will let you handhold easily.
3. Starting about a stop below the metered reading, take a quick bracket of images, using shutter speed  to go up in 1/3-stop increments.
4. Shoot until the camera’s highlight warning is activated. Decide if the warning is for specular clipping or diffuse highlight detail clipping. If it’s specular, then keep shooting until you have highlight detail clipping.
5. Make a note of the filename for this frame. Take a smartphone or point-and-shoot snapshot of the back of the camera; you want a shot showing the image with the highlight warnings and another shot that shows the histogram.
6. Continue the bracket, in 1/3rd-stop increments, for another two stops.

In Your Raw Processor

1. In your raw processor, ingest the raw files. Leave the images at their default values. Find the image you took note of, where your camera flipped on its highlight alert.
2. Turn on the clipping warnings in your raw processor² and look at your selected image. Does it have a highlight clipping here that matches the one on your camera? How do the histograms compare?
3. Now move through your bracket and find the first image that activates the raw processor’s clipping warning. Calculate the difference in exposure between this image and the one that first set off your camera’s alert. You might find that there’s as much as a stop of exposure between the two.
4. Bonus: You can experiment with the different adjustments that are available to recover highlight data that initially appears clipped. Try using the Exposure, Highlight Recovery or White Point sliders to recover the clipped tones on each of your clipped images. You’ll want to make your adjustments minimal, paying attention to how the tools affect the rest of the image.

Takeaway

There’s a difference between when your camera tells you that it’s overexposing and when it actually is. There’s also a difference between specular clipping and diffuse detail clipping. With this kind of knowledge, you’ll be in a much better position to judge your histograms and use the highlight warning effectively.