Colour background using flash gel

To change the colour of background walls using colour gel

On the background walls, can use bare flash with coloured gel, aim just a short distance away from wall. make sure the flash does not hit the subject else there would be unwanted shadows.

On subject, use flash with softbox. Dont place it too far from subject else the white light will spill to the background wall and thus diffusing the colour behind.

Note: Do not use diffusera such as umbrellas for the front fill light for subject. Use things like softbox or fire fly which have smaller fill area.