NEW - Ken Gilbert

Do you have some near-perfect digital
photographs that are marred by
overexposure, underexposure, or low contrast? If
you’re itching to fi x them, but reluctant to muck about
with Adobe Photoshop’s Curves and other manual
adjustments, Photoshop also offers some jiffy fi xes.
Called Layer Blending modes, these use math to
combine the pixels of one layer with the pixels of an
underlying layer to create an improved image. First
step: Duplicate the image layer, which stacks your
picture on top of itself. Then click on the drop-down
menu in the upper left corner of the Layers panel to
change the blend mode from Normal
to one of the following:
nMultiply. This darkens images
and increases highlight
contrast, just what you want
for an overexposed photo. It
multiplies each layer’s pixel
values together.
nScreen. Basically the
inverse of Multiply, this
lightens images and increases
shadow contrast, good for
underexposed photos.
nOverlay and Soft Light. These, in
effect, multiply the shadows and screen the
highlights, which increases contrast. Soft Light is a
weaker version of Overlay.
You control the degree of the blend effect by
adjusting the opacity of the upper layer—the lower
the percentage, the more transparent the layer. When
you get the look you want, merge the layers and
you’re done. Duplicating and blending layers takes
only a few keystrokes, so it’s well worth trying for
quick fi xes of your photographs. —Timothy Edberg
You’ve said to use a circular polarizer
to make skies bluer, reduce refl ections,
etc. Aren’t all polarizers circular? And
how does a linear polarizer work? —F.P.
“Circular” has nothing to do with its
shape—circular polarizers can also be
rectangular. And linear polarizers are also
made in a round, rotating fi lter mount.
Both types reduce refl ections by aligning
light waves in ordered ranks. A linear
polarizer passes waves that are aligned in a
linear fashion; think of a slotted grate.
Circular polarizers work the same way,
except that they add an additional layer of
BLENDER RECIPES:
The Multiply Blend mode
in Adobe Photoshop darkens
an overexposed image and
improves colors (A). Screen
adds snap to an underexposed
frame (B). Overlay opens up
shadows and enriches
colors (C).
90 POP PHOTO MAY 2009
fi lter material, called a
quarter-wave plate, that
cranks the polarized light a bit
off kilter. (It’s much more
complicated, but believe us, you don’t want
to read all about it.) “Circular polarization”
was already a science term when the fi lter
was invented, adding to the confusion.
Circular and linear polarizers produce the
same effects. But the latter can create
problems with autofocusing and in-camera
metering, for which DSLRs use
semitransparent mirrors (also called beamsplitters).
Linear polarizers tend to
(surprise!) suppress refl ection in
the beam-splitters.
Circular polarizers’
slight rescrambling
of light allows the
AF and metering to work normally, which is
why DSLR makers recommend them.
Circular polarizers are considerably more
expensive—sometimes twice the price. You
can economize by using a linear polarizer if
you’re willing to focus manually (or
manually touch up the AF) and diligently
check your exposures using a histogram. p
FIELD GUIDE: How can you tell linear
from circular? Often by the markings. Also,
a linear polarizer works the same when
reversed on your lens, whereas a circular
one has little or no effect when reversed.
TIMOTHY EDBERG (6)