---
title: "Set the brightness of the Vicon IR lights"
canonical: "https://help.vicon.com/space/markerless/261718324/Set%20the%20brightness%20of%20the%20Vicon%20IR%20lights"
format: markdown
---
Vicon Shogun Markerless is supplied with two options for the brightness of the IR lights: 45% or 90%. 

> ✅ **Tip**  
> ✅ For 30–90 Hz tracking, reduce the brightness of the lights to 45%; for rates 90–120 Hz, use the maximum brightness of 90% and increase the shutter duration.

To choose the required option, you select the appropriate setting for the Lock properties in the **System** panel. 

> Macro (scroll-pagebreak)

**To specify the brightness of the IR lights:**

1. Ensure that the system is powered and that all the Vicon IR lights are connected to the Vicon Lock via the supplied RCA cable.
2. In Shogun Markerless, go to the **System** panel and in the **Connectivity Devices** section, select the Lock.
3. In the Lock's **Properties**, go to the **GPO Programs** section and for each connected light, click the relevant folder icon.  
By default, the location of the supplied .*gpo* files is displayed.
4. Select the required option and then click <span style="color: #172B4D">**Open**</span>:
  - For 30–90 Hz tracking, select *IR_Lights_DutyCycle45.gpo;* or
  - For 90–120 Hz tracking, select *IR_Lights_DutyCycle90.gpo* (and increase the shutter duration).
5. For each connected IR light, repeat Steps 3 and 4.