Cloudy days are nature's softbox.
Cloudy days can present many opportunities for great photographs. In fact, once you discover how easy it is to get great results, you'll look forward to a cloudy day as much, if not more, than a sunny day.
The studio photographer's arsenal includes a number of tools to soften and redistribute light to the best advantage of the subject. Among these tools is the Softbox which provides soft, even lighting by using a diffuser in front of the light.
In outdoor photography, cloud cover diffuses the light of the sun much like a photographer's softbox, producing a soft even light that results in softer contrasts. While high contrast can be quite dramatic, the softer contrast allows for more detail in both the light and the dark areas of your photograph. The softer light is also more flattering for portraits or candid shots of people.
On your first few cloudy day adventures, consider taking your digital camera. In spite of the differences in the cameras, what you learn about how the lighting changes your compositions and setup will be equally useful with your film camera. And with the digital, you'll feel free to experiment without the added cost of film on your mind.
Some difficult subjects which benefit from the diffused light include waterfalls in shadowy forested areas, sea life caught in a tide pool and wildlife hiding in the shadows, as well as close ups of flowers and people.
Diffused lighting is not as bright as direct light, indoors or out, and you will need to compensate with a slower shutter speed. Or widen the aperture and adjust the depth of field. You should count on needing your tripod for wide or long shots. The picture can be blurred by even slight camera movement with really slow shutter speeds, so use your remote if you have one.