The first choice to make is whether to shoot indoors or outdoors. Unless it's night time, outdoors is usually brighter than a lit indoors area. This means that working without flash or extra lights is often easier outside, with faster shutter speeds available and hence less chance of camera shake or subject movement. If it's very bright outside though, it can mean you're limited in terms of slow shutter speeds and wide apertures, so if you're shooting something you can pick up and move, especially if it's a still life type object, taking it inside sometimes affords you more freedom to shoot how you wish. Inside lighting options include flash, desk lamps, windows, torches and normal room lights among others. If on the other hand you're shooting something fast moving like children, moving outside will allow you more likelihood of being able to catch a sharp image.
When you shoot in relatively dim conditions without flash or extra photo-specific artificial lights it's often referred to as 'available light' photography. This can be done indoors using windows or the light spilling from another room, or outdoors using street lights, light from a window, or even passing headlights if you're particularly careful about where you set up. The point is using 'borrowed' light - whatever light is already available in a location is what you have to work with, without adding more of your own. Available light photography techniques are often used for portrait and glamour shots, where the subject is lit by light spilling through a blind or from a window a little way away. There's also nothing to say you can't reshape or redirect the light using diffusers and reflectors to fill shadows or deepen them, or reduce harsh direct light. a very useful purchase I made some time ago is a lastolite 5-in-1 reflector which provides, as its name suggests, five light changing options. A diffuser for softening light, white, silver and gold reflectors for filling shadows and adjusting the tone of light, and the intriguing black reflector which effectively takes light away. The black side essentially replaces any reflective surface which is pushing light back onto the subject, with a non-reflective one which may, depending on scene arrangement, itself reflect on the model or subject's surface or skin.
As I said at the top, the first choice is indoors or outdoors, and the best thing about the outdoor option is the range of lighting options it provides when you work al fresco. even though you'll tend to be using one main light source during daylight hours - the sun - it doesn't have to be direct sunlight to be worthwhile. In fact, while bright sunlight is great for warm summer or autumn landscapes (or any time of year - blue skies and fluffy white clouds add to most landscape shots), plus shots of the kids on holiday, and pictures of your house for Rightmove, most photographers prefer things a little more subtle for anything but landscapes. A cloudy sky is like the world's biggest natural softbox and lights detail subjects much more sympathetically. Portraits especially benefit from gentler lighting, and still life shots of flowers, leaves, nature in general do not gain anything from being too harshly lit. Portraits against an important or relevant background are easier to expose for in softer, less directional light too. In short, cloud rules for outdoor non-landscape shots. You just have to be careful not to leave the shots looking flat and lacking contrast. If options are limited and you find yourself shooting portraits in bright light, a little fill-in flash could be your friend, but I'll cover that in another post.
Time of day also makes a big difference to your final image. Sunrise and sunset light for example have completely different attributes and qualities, with sunrise being cooler and gentler as a rule, while sunset is very warm and quite directional. If you can drag yourself out of bed in time to catch a sunrise over your favourite landscape feature, the results can be well worth the effort. Just be aware that some mornings (many, if my own track record is anything to go by) don't really have a sunrise to speak of. I remember one early morning in the lake district, getting up at 5am to head to a spot I'd scoped out the previous day on the shore of Bassenthwaite Lake. I waited for the first hint of light, set up the tripod and waited. Three hours later I crawled back into bed. All that had happened was that the sky got progressively lighter grey, as unexpected cloud cover had sneaked up in the early hours. If you want to see examples of sunset vs sunrise over the same landscape, one of my favourite photography books is Charlie Waite's 'Seeing Landscapes' which has just such an example, over a rural scene in Tuscany.
And so to artificial light. Whether used in darkness or light, whether used as the main or sole light source or just to add a sparkle to an already lit scene, adding light gives you ultimate control over the presentation of your subject. First and simplest is the situation where you're lighting the scene using only light sources within your control. This applies to scenes lit with the flash on 'auto', as the camera will usually choose exposure settings which cause the flash to entirely overwhelm the ambient light, leaving the whole scene lit as if flash was the only light source, leaving shadows on otherwise well-lit surfaces behind the subject. The harsh effect of direct flash can be softened in a number of ways which I'll cover in the aforementioned later post, or you can balance it with other light sources using your flash exposure compensation setting, if you're lucky enough to have the setting and a dedicated flash (you can simulate the same-ish effect using a non-dedicated flash with auto modes). What this does is reduce the amount of light the camera will use to expose the scene, by a specified amount. The stops work in the same way as regular exposure 'stops' i.e. Minus-1 stop means the camera will use half the flash power, leaving flash to ambient at 50:50. This is a good first test point if you've determined that 100% flash is not what you need. Once you've seen the result you can adjust accordingly. If you're on film or short of review time, many mid range SLRs have flash exposure bracketing which works like regular bracketing, shooting three images with flash exposure compensation adjusting itself across the three according to a range you've specified.
So that I think will suffice as the absolute basics of lighting your scene. I'll come back to more advanced topics another time, but apart from using a flash diffuser, I rarely step beyond the bounds of what I've described above.
Have fun.
