Knowledge ·
Beam angles and accent ratios: planning contrast
How beam angle, distance and accent ratio work together — and why 24° is the most-specified spotlight in retail.
An accent only works if it is brighter than its surroundings. The question is by how much, and which beam gets you there.
Accent ratio
The accent ratio compares the illuminance on the object with the general illuminance around it.
| Ratio | Effect |
|---|---|
| 2:1 | Barely noticeable |
| 3:1 – 5:1 | Clear but calm emphasis |
| 10:1 | Dramatic, the object stands out strongly |
| 15:1 and above | Theatrical; the surroundings drop away |
Beam angle and spot size
The beam angle is where intensity falls to 50% of the peak. The light spot diameter at distance d is approximately 2 × d × tan(beam/2).
| Beam | Spot at 3 m |
|---|---|
| 15° | ≈ 0.8 m |
| 24° | ≈ 1.3 m |
| 36° | ≈ 1.9 m |
A 24° beam at typical retail ceiling heights covers a mannequin or a display table — which is why it is the default. Use 15° for small objects or long throws, 36° for shelving bays and walls.
Practical rules
- Narrowing the beam raises the centre illuminance at the same wattage — often a better route to a higher ratio than adding power.
- Keep the general level low enough. Raising every light raises nothing.
- Aim from about 30° off vertical to model three-dimensional objects and avoid reflections.