Home > Free Information > Measuring Light Intensity

If you want to really know the light levels in your growing areas, you should consider purchasing a decent light meter.  However, most orchid growers love to take photographs of their flowers, and that may provide a reasonable alternative.  If you're one of those, and have a camera with a built-in light meter - most single-lens reflex (SLR) cameras do - then you can use it to measure the light intensity, too.

You only need three things:  your camera, a piece of white paper, and the calculator below.

Simply put the paper in the location you wish to measure, point the camera at it so it fills the frame completely - trying to shoot as close to perpendicular to the paper as possible, adjust the aperture so that you get a decent shutter speed, and then use the ISO setting and those values in the calculator to determine the foot-candles of light intensity.  (Note that these numbers are not exact, but certainly give a "ballpark" figure to work with.)