Adobe Photoshop CS6 User Manual page 696

Adjust light properties
1. In the Lights section
2. In the lower half of the panel, set the following options:
Preset applies a saved group of lights and settings. (See
Light Type Choose from the options described in
Intensity Adjusts brightness.
Color Defines the color of the light. Click the box to access the Color Picker.
Image For image-based lights, specifies a bitmap or 3D file. (For dramatic effects, try 32-bit HDR images.)
Create Shadows Casts shadows from foreground surfaces onto background surfaces, from a single mesh onto itself or from one mesh onto
another. Disabling this option improves performance slightly.
Softness Blurs the edge of shadows, producing a gradual falloff.
3. For point or spot lights, set these additional options:
Hotspot (Spot lights only) Sets the width of the bright center of the light.
Falloff (Spot lights only) Sets the outer width of the light.
Use Attenuation Inner and Outer options determine the cone of attenuation and how fast light intensity decreases as distance from objects
increases. When an object is closer than Inner limit, light is full strength. When an object is further that Outer limit, light is at zero strength.
At intermediate distances, light attenuates linearly from full strength to zero.
Hover the pointer over the Hotspot, Falloff, and Inner and Outer attenuation options. Red outlines in the icon to the right indicate the
affected light element.
Position lights
In the Lights section
Rotate tool
(Spot, infinite, and image-based lights) Rotates light while maintaining its position in 3D space.
To quickly aim a light at a specific area, Alt-click (Windows) or Option-click (Mac OS) in the document window.
Pan tool
(Spot and point lights only) Moves the light to a different position in the same 3D plane.
Slide tool
(Spot and point lights only) Moves the light to a different 3D plane.
Point Light at Origin
(Spot light only) Directs light at the center of the model.
Move to Current View
Places light in the same position as the camera.
To precisely position image-based lights, use the 3D Axis, which wraps the image around a sphere. (See 3D Axis (Photoshop Extended).)
Add light guides
Light guides provide spatial reference points for your adjustments. These guides reflect the type, angle, and attenuation of each light. Point lights
appear as a ball, spot lights as a cone, and infinite lights as a line.
At the bottom of the 3D panel, click the Toggle icon
You can change the guide color in the 3D section of the Preferences dialog box.
of the 3D panel, select a light from the list.
Add or delete individual
of the 3D panel, select any of the following:
Save, replace, or add groups of
lights.
, and select 3D Light.
lights.)