Vertical vs Horizontal Footcandles: Why It Matters
Horizontal footcandles measure light on the flat playing surface; vertical footcandles measure light on a vertical plane — players' faces, the ball in flight, and what cameras see. Horizontal illuminance serves general play. Vertical illuminance is what lets athletes track a ball in the air and lets cameras capture clear images. The two are not interchangeable, and good designs specify both — getting one right while ignoring the other produces a field that looks bright on paper but plays or films poorly.
This guide explains the difference in practice, why the vertical number is the one people forget, and when and how it gets designed in.
The difference in practice
Picture a baseball outfield lit to a strong horizontal footcandle average. The grass is bright, the spec sheet looks great — yet a high fly ball seems to vanish at the top of its arc. The reason is that a ball 60 feet in the air is lit by vertical illuminance, not the horizontal light measured on the turf. The same gap shows on camera: a broadcast picture depends on light striking the vertical plane the lens images, so a horizontally-bright, vertically-dim field looks flat and underexposed on television.
What each orientation serves
| Orientation | Lights | Critical for |
|---|---|---|
| Horizontal | The flat playing surface | General play, ground-level action |
| Vertical | Players' faces and the ball in flight | Ball tracking, broadcast, higher classes |
When vertical footcandles matter most
Vertical illuminance becomes decisive in three situations: aerial ball sports (baseball, football, soccer, volleyball, cricket) where players track a ball high in the air; any filmed or televised venue, since cameras image the vertical plane; and higher classes of play, where IES RP-6 adds explicit vertical targets on top of the horizontal ones. Recreational fields are frequently designed primarily to horizontal footcandles, but the moment a field hosts competition aerial play or a camera, vertical illuminance moves to the front of the design.
How vertical illuminance is achieved
Vertical light comes from lighting the field from multiple directions at appropriate angles, so a ball in the air is lit from more than one side and reads clearly against the sky from every camera and player viewpoint. This is the structural reason higher classes of play use 6–8 poles or high-mast arrays rather than a minimal four-pole layout: more aiming points build even vertical illuminance that a sparse layout cannot. Duvon's higher-output series and multi-pole layouts deliver even vertical light where the class of play requires it.
Frequently asked questions
What is the difference between vertical and horizontal footcandles?
Horizontal measures light on the flat surface; vertical measures light on a vertical plane — faces and the ball in flight, and what cameras see. Horizontal serves general play; vertical is critical for ball tracking and broadcast.
Why do vertical footcandles matter?
A horizontally-bright field can still make a high ball hard to track and look dim on camera, because those depend on vertical light.
When are vertical footcandles required?
For aerial ball sports, filmed venues, and higher classes of play. Recreational fields are often designed mainly to horizontal footcandles.
How is vertical illuminance achieved?
By lighting from multiple directions at appropriate angles — which is why higher classes use 6–8 poles or high-mast arrays.
Should my design specify both?
Yes for any competitive aerial sport or filmed venue — specifying both horizontal and vertical footcandles ensures the field plays and films well, not just looks bright on paper.
Ask about vertical-illuminance design with a free certified photometric layout. Request it at duvonlighting.com/free-quote.