Here’s a helpful 6-minute tutorial by photographer Dustin Dolby on how you can photograph group product photos using only a single speedlight.
Dolby places a number of shampoo and conditioner bottles on a sheet of acrylic and then uses light to craft space.
These frames can then be composited into a single image using Photoshop’s Lighten blending mode.
The fact that you’re blending in the background as a separate frame means you can apply a hue saturation to that layer to make it look as though you used a colored gel.
Here’s the final group product photo that resulted from using this technique with a single speedlight:
“I don’t think things should be shot with one speedlight like this typically or in a professional environment,” Dolby says, “but by boiling things down to the one light, we help people out who have [less] gear […] but also it forces us to understand each exposure.”