Lighting has to be one of the trickiest aspects of macro photography to master. Mixing flash and natural light is a challenge in any genre, but when working on images of very small subject matter it can seem impossible to capture a balance of softness and shape. This is because the light source (even small flash, such as a speedlight) is large, relative to the subject, meaning the light spreads across the frame. If you try to limit the spread, by removing a diffuser, you create hotspots. Meanwhile if you add a diffuser the light seems to lose all sense of direction and structure. It’s the equivalent to lighting a person with a 3x3m scrim and attempting to introduce a spotlight effect – not an easy feat!
The aim with macro lighting is to prevent unwanted spillage onto surrounding areas and background details, while managing the inevitable micro contrast on the subject itself, caused by reducing diffusion.