Most lighting equipment falls into one of three different classes: Light Sources, modifiers and grips
Grips expand to encompass all the stuff we use to support and hold our gear. Be it your camera, or lighting equipment such as stands and clamps.
Light modifiers in studio photography are anything we attach to (or hold in front of) our flash or light source, to control the light pattern it normally emits. These would include umbrellas, softboxes, and reflectors.
Light sources are any number of things that emit light onto our scene. It could be available light such as the sun or tungsten light. (Source: http://photography.tutsplus.com/articles/an-introduction-to-indoor-and-studio-flash-photography--photo-4229)
Light source: What is a Continuous light ?
With continuous lighting, there's no need for modeling lights, which run very hot and can limit your use of modifier. However the scene looks to your eye will be how it appears on camera.
This can be a big bonus when learning to use artificial lighting, since you can move the light around and get instant visual feedback without having to shoot anything at all.
Lighting ratios are right there in front of your eyes. No flash meters, no particular need to shoot manual, just flip switches until you like what you see, then adjust aperture and ISO accordingly.
What the subject sees is also what they get. No blinking or disorientation from popping strobes all over the place, just an initial adjustment to the unusually high light levels. (Source: http://photography.tutsplus.com/tutorials/strobes-or-continuous-lighting-whats-the-better-choice-for-you--photo-14549)
When choosing a continuous daylight, photographer tend to look at data such as the power, color temperature which is measured in Kelvin (Unit of measurement for temperature and often used in the measure of the colour temperature of light sources), the type of usage they wish to have.
Continuous light may cause your subject’s pupils to become smaller, just as they would under any brighter lights, or outdoors. This might be preferred over the look of larger, dilated pupils when working in darker environments with flash.
Depending on the number and power of the lights you’re using, you’ll probably find higher ISO settings are necessary when compared to shooting with flash/strobe lights.
Tungsten light sources produce warmer light than flash and other types of lighting. This is not always a problem. But other lights like CFLs and mercury vapor lamps can introduce color casts in your images. If you’re using mixed lighting (cooler lights like flash/daylight, along with tungsten lighting) you might have to color-correct for proper white balance. This is often accomplished with gels or in post-processing. Of course, sometimes the differences in color temperature are a desired effect. (Source: http://www.lightstalking.com/continuous-lighting-light-sources).
There a numerous brands that manufacture continuous daylight. In our shop, we propose Continuous light from FotoQuantum and Continuous Daylight from Walimex.
A lighting configuration between 2 to 3 continuous light is recommended. This technique can be used to eliminate shadows cast by foreground elements onto the background, or to draw more attention to the background. It also helps to off-set the single eye nature of the camera, this means that it helps the camera give depth to the subject. (source: http://en.wikipedia.org/wiki/Three-point_lighting)
Different power and usage
Continuous light output is measured in watts. The choice of power output is determined by the type of photography.
Continuous light up to 450W
The continuous lights with power up to 450W are used as fill lights, to illuminate a background for example. They are well suited for small product photography as well as half body portrait photography.
These lights are used with medium product photography as well as full body portrait photography or fashion photography.
These lights are used with big product photography as well as full body portrait photography or fashion photography
Powerful, they are used in big studios for group pictures, and other types of photographies which require an important amount of power.
Quartz light provide better colour consistency and brightness. If you're only doing still-life shots of non-perishable items, or interior architectural photography, quartz lights can be a great choice. The bulbs don’t last long, but unlike tungsten, there won’t be a drop-off in colour temperature during their lifetime.
LED lights are characteristically low in power consumption and create a cool light while maximising durability. Their color temperature is usually of 6500K. They are perfect for video shots and chroma key work, as they are flicker-free. They come either in panels to cover a relatively large surface, or in smaller version to mount on the hot shoe of a camera.
Ring lights are used for macro-photography and also close up in beauty and fashion photography. It gives a round effect to the model's pupils.
A classic light modifier would be a brollie. It exists in different sizes and colours. It is usually fitted through the standard reflector or a socket in the continuous light. A white umbrella helps to soften the light and make it even. The silver umbrella provides harsh and bright light whereas a gold brollie give a warm tone to the pictures.
Useful, the softbox is a good addition to a light. It comes in different size and shape and is usually fitted with a front and rear diffuser. The main advantage of softboxes is that, they produce very soft shadows, almost to non-existent. The octagonal softboxes/ octaboxes reproduce the effects of umbrellas, whereas the striplights allow narrow lighting for a ‘spotlight’ look. The rectangular softboxes are useful when wanting a source of constant light from head to toe of a person. The square softboxes are ideal for portraits and nature.
The barn-door create a spot light. Usually, daylight kits come with their own barn door and their own softboxes, it is therefore not possible to adapt other accessories on these lights and they are less polyvalent than studio flashes.