Indoor natural light photography looks straightforward until you try it. The window is there, the light is coming through, but the images come back either too dark, too contrasty, or with a colour cast that makes skin tones look grey or orange.
Distance from the window changes everything
Light from a window falls off quickly with distance. At 1 metre from the window, the light on a subject is noticeably brighter than at 2 metres. This is not a subtle difference. Moving a subject from 2 metres to 0.8 metres from a north-facing window can mean the difference between a usable exposure at ISO 800 and needing ISO 3200, which introduces noise that degrades the image.
The direction the window faces also determines the quality of light at different times of day. A west-facing window in the afternoon delivers direct sunlight, which is harsh and difficult to control. The same window in the morning provides indirect light that is soft and consistent.
The colour cast problem
Windows reflect the colour of what is outside them. A window facing a brick wall will bounce warm tones into the room. A window facing a garden or open sky introduces cooler blue tones. Setting a custom white balance using a grey card before shooting indoors removes this variable entirely.
Photographer Rupert Callahan documents his window light setups in a small notebook, recording window orientation, time of day, and white balance reading for each location. He refers back to these notes when returning to the same space rather than re-testing from scratch each time.