Checking the Enable realtime lights option will make light sources update instantly as you work, letting you preview how they will change when you try out different settings.

This option can be found in the following areas:

• The Control Panel > Graphics tab
• The Rendering Tools Extension tab > Lighting section
• The Preview area in Photo Lab
• The Lights Extension

Enabling realtime lights when using the photograph setup Product lighting will show a very dark, practically black, view in Photo Lab and the 3D View until lights are placed in the drawing. Although this makes it hard to make out details, it does not have a negative impact on the actual rendering, which will look just fine.

Because this is a very resource-intense operation, it is turned off by default. It is recommended that the checkbox remains unchecked when working on larger drawings with many light sources, as this can slow down the 3D graphics.

Enable Realtime Lights off	Enable Realtime Lights on

You will notice that with Enable Realtime Lights on, the lighting is quite extreme. The contrast between light and dark is exaggerated so that it is easy to see light sources, where they are pointed, and how they will blend with other sources. Once the image is rendered, the lighting will have a much more realistic appearance:

The appearance of the Realtime Lights mode can be adjusted in two ways. 

1. Switch your mode in the Photo Lab Photograph setup.
2. Open Light Settings on the Lights Extension tab and change the Global lights settings from the drop-down list.