With many different types of light source offering a huge amount of variables you can change on each, the field of lighting can be a difficult choice to get the right tools for the job at hand
With so many options to choose from its difficult to pick which is going to offer you the user the right characteristic of light.
Using Flash and Strobes
The first (my preferred) flash, offers much more flexibility for the photographer, as more styles of units are readily available from mains, pack and battery operated heads. Along with current technologies bringing in features like TTL* and HSS**, wifi connectivity, wireless control and even apps for your smartphone to the market.
They are usually a little more portable, or portable options are widely available, with more variables to control such as colour temperature and flash duration this becomes a powerful tool to sculpt your image with light, coupled with a wide selection of modifiers to change the way the light performs and allow you to control these characteristics.
Using larger light sources will give you a softer finish to your light allowing for soft shadow detail and graduated tones between the light and dark areas of your image. Where as using small and confined light source will give you harder light and give a detailed edge to your shadowed areas.
One of the other major advantages with using flash lighting is the power available, with short burst of high intense light, the ability for the flash to output more power over a continuous means you will be able to use a wider range of settings on the camera and shoot at lower ISO levels.
Continuous lights as stated in the name run constantly and therefore can be quite uncomfortable when shooting people, as they will have a more dazzling effect on your subject, whilst flash offers a short powerful pop of light that is over before the subject has even noticed
More commonly used in the video industry however modern advancements in lighting technologies have seen a massive increase in usage of continuous lighting within the stills trade. Again these light sources come in a massive selection from daylight balanced lamps, LEDs and tungsten/halogen.
With fluorescents normally the light source is quite weak but offers an accurate daylight balance, these lamps run at reasonable temperatures making them quite manageable.
LED lamps these come in a range of colour temperatures and some more modern units even have the ability to control this offering the user the ability to change from 3200k - 5400k, however LEDs are very small sources of light and therefore become a very hard and direct source of light this means that used in a portrait environment they can be very distressing for the subject.
Halogen or Tungsten lighting offers the user a much more powerful output, but in doing this also use a lot of energy so can send your studio electric bill though the roof, also to generate this amount of output they run hot, this in turn then becomes a hazard that is best avoided. With lamps blowing a lot easier and the risk of fire when using them with modifiers, LED and fluorescent lighting have rapidly taken over the continuous market.
Using the different types of continuous light sources opens a new set of parameters for the photographer, allowing them to play more with shutter speeds creating longer exposures and adding blur or movement to a subject and exploiting the modern day camera sensors ISO capabilities.
The major advantages of using continuous lighting source is you see what you get. As the light is already set up and running at the power you are about to take your photograph at, the results will be readily available through the viewfinder before ever depressing the shutter release. This make composing for product work very easy. Again working with people or animals continuous lighting have both disadvantages and advantages, when working with powerful continuous lighting systems more like the LEDs available, the lights are very dazzling and almost blinding for the model, meaning most work they will start to squint after 2/3 shots, however in a more forgiving environment with larger softer diffusers over your light source more commonly used with fluorescent lighting, the continuous light source can be less distressing for infants and pets as no flash is produced.
The sun is a small and powerful light source giving great contrast and detailed edge to the shadows. On an overcast day the clouds act like a large diffuser panel, turning our hard direct small light source created by the sun into a soft large light source, giving a nice softness and wrap around light, graduating the shadow detail.
So which to choose
Honestly, each have their pros and their cons, and are different tools for different jobs You can use both at once for example shooting portraits with soft continuous lighting setup for the subject, while popping a low powered strobe at a wall behind them will give the illusion of a studio white seamless background.
But wanting to go for just one then it really depends on your needs. Are you after power or portability, then strobes are going to be more suited to your needs. if however you are stuck in the studio or shoot most things wide open (the widest aperture your lens allows) then continuous lighting will be offer more advantages for you.
* TTL - Through the lens - a type of metering system that allows your camera to communicate with the flash system and provide you with the correct amount of light depending on the camera's setting
**HSS - High Speed Sync - Communication between your flash unit and camera allowing you to wind your shutter speed beyond your camera's x-sync speed