Active D-Lighting - Nikon D300 Complete Manual

V1.02
find it useful, though, because they always shoot in one
exposure mode (usually Aperture-preferred) and it gives them
a convenient way to quickly take an exposure at a value
different from the metered one (i.e. take a picture, twirl a
Command dial (usually Rear, as the aperture is controlled by
the Front), take another picture at the compensated setting).

Active D-Lighting

Nikon's latest cameras have a new control that intersects with
exposure: Active D-Lighting. Before telling you how the
exposure interaction works, I first need to describe what "D-
Lighting" is.
You may be surprised to find out that D-Lighting has its
origins in Nikon's scanning software, where a feature
originally called DEE (Dynamic Exposure Expansion) first
appeared. What DEE and its progeny attempt to do is re-
position highlight and shadow information.
Let's keep the discussion simple and hypothetical for a
moment. Assume that you had an 8-bit data set that had three
bit values in it: 1000 0000, 0000 0010, and 0111 1111
(those are equivalent to 1, 128, and 254, or "close to black,"
"middle gray", and "near white"). Now let's apply a shadow
boost and highlight reduction scheme to our data. We might
end up with values of 0100 0000, 0000 0010 and 0011
1111 (that's 3, 128, and 252). Note how the middle value
remained unchanged, but the shadow value rose and the
highlight value lowered. That's something akin to what DEE
(and now D-Lighting) does, though the formula for moving the
values is not linear and variable. Moreover, highlight changes
are smaller and more subtle than shadow changes. Think of it
as a method for moving shadow and highlight detail into the
more visible middle-ranges of your exposure data.
Many recent Nikon DSLRs have had D-Lighting built in (as
does the D300). This feature lives on the RETOUCH menu
and is used to apply value changes after the fact on images
you've shot (see "D-Lighting" on page <710>). What's new
Thom Hogan's Complete Guide to the Nikon D300 Page 310