There seems to be some confusion about the use of Active D-Lighting. As a reminder, Active D-Lighting (ADL) is a setting in the camera that is used for high contrast scenes. It potentially applies an exposure adjustment to reduce exposure, and applies a complex curve to brighten shadows while protecting highlights.
The camera used here is a D800E with a Nikon 24-70 lens. The camera settings were Aperture Priority, ISO 200, f/8, and 1/100 sec with -0.7 Exposure Comp.
The amount of the exposure adjustment varies depending on the setting, so the strength of the curve also varies with the setting. The exposure adjustment is in 1/3 stop increments starting with no adjustment at ADL LOW, -0.3 stops at ADL Normal, -0.7 at ADL High, -1.0 at ADL Extra High, and -1.3 at ADL Extra High 2.
The exposure adjustment is baked into the image - you can see changes in the exposure settings as you make changes in ADL. The exposure cannot be changed in post processing.
The complex curve to protect highlights and brighten shadows can be changed after the fact in Capture NX2 - but only if ADL was originally turned on in the camera. If ADL was turned off in the camera, it cannot be activated in post processing.
My position is that you should normally set Active D-Lighting to Low in the camera since it does not change exposure, applies a minimal curve that can be turned off, and it retains the ability to make further adjustments in Capture NX2 during post processing.
If you use Nikon View NX2 for post processing, the setting is applied but cannot be changed. If you use Adobe programs or other programs that do not use the camera settings, the curve is ignored and only the exposure adjustment is used.
Here are some examples to an image from a recent scouting trip.
Figure 1. This first image shows the image with ADL turned off.
Figure 2. The second image shows the image as shot - with ADL Low activated.
The change is very subtle and therefore hard to see, so a comparison of the two images follows.
The ADL Low image above (on the left) reduces highlights a little and slightly brightens the shadows. This is why I see no adverse impact of setting ADL Low in the camera as my default setting.
This ADL increase applies the additional curve to the image, but the original exposure cannot be changed. This is an extreme setting, but it gives an idea of the potential impact. The highlights and sky are a little bright here, but can be pulled back down with other edit steps.
This image has the ADL setting changed from Lo (as shot) to Extra High 2, and D-Lighting is turned on with Better Quality and the default settings. The edit was applied selectively, only to the shadows area and not applied to the sky.
Figure 6. Comparison between the image with ADL Low, and the maximum recovery possible with ADL Extra High and D-Lighting Better Quality at default settings applied selectively.
In conclusion, using Active D-Lighting in camera, set at Low, can and should be a default setting, as the effects are minimal. This gives you an additional editing option and greater latitude for adjustments than just D-Lighting in post-processing when ADL is set to Off in camera.