add field lighting page

docs-source/field.md

@@ -19,6 +19,7 @@ The following pages assist with materials and camera selection.
 - [Subflooring and Carpet](field/carpet.md)
 - [Camera and Lens Selection](field/cameras.md)
 - [Camera Field of View Calculator](field/camera-calculator.md)
+- [Lighting](field/lighting.md)
 
 ## Layout
 
@@ -48,6 +49,7 @@ caption: Contents
 field/carpet.md
 field/cameras.md
 field/camera-calculator.md
+field/lighting.md
 field/complayout.md
 field/lablayout.md
 field/network/compute.md

docs-source/field/lighting.md

@@ -0,0 +1,17 @@
+# Lighting
+
+The rules do not specify lighting. These recommendations come from team and event experience.
+
+- **Avoid fluorescent tubes and lights with low-frequency pulse width modulation dimming.** They flicker at tens to
+  hundreds of hertz. At the few-millisecond exposures used for vision, each frame samples a different brightness, and
+  rolling shutters show banding.
+- **Diffuse your sources**, by spreading them across the ceiling or using diffusion panels. Illumination should be as
+  homogeneous as possible across the field. A brightness gradient shifts the marker colors seen by the camera, so one
+  color calibration no longer fits the whole image.
+- **Avoid or minimize daylight.** Its variance forces continuous recalibration. Blackout curtains are usually enough.
+- **Aim for color temperatures of 5000K to 6500K.** This range gives the best contrast between the marker colors and the
+  orange ball. Warmer light lacks blue and narrows the separation.
+- **High brightness is key.** It allows a short exposure, which reduces motion blur of fast robots and the ball.
+
+Fix exposure, gain, and white balance in the camera and calibrate under the lighting you will play under. See
+[software support](cameras.md#software-support-by-league-vision-software) on the camera page.