Often overlooked in favour of flash lighting, continuous lights have many advantages. We take a look at the different lights that are available.
Whether to opt for continuous or flash lighting is a decision that anybody investing in studio lights will have to make. Years ago, the decision was easier due to the fact that continuous studio lighting largely relied on using high-powered incandescent bulbs that generate a huge amount of heat. However, there have been a number of advances in continuous lighting. The highpowered, electricity-guzzling tungsten bulbs now have competition in the form of more energy-efficient, light, cool sources.
Flash vs continuous light
The obvious advantage of using continuous lighting, instead of flash, is the fact that the light source is the same one that is used to illuminate the image. While most studio flash heads have modelling lights, these only give you an idea of what the final image will look like. The lower-powered modelling lights do not replicate exactly how a split-second bright burst of flash will look. Continuous lights, on the other hand, show exactly how the image will look and take the guesswork out of adjusting the lights for best results – what you see in front of you is what will appear in the final image. Another advantage of continuous lights is that they don’t need to be triggered, so they will work with any camera and without any cables or wireless trigger devices.
With these plus points in mind, you start to wonder why flash is still preferred by many photographers. In the past, this was partly down to the heat generated by high-powered, continuous tungsten lights, which can make it uncomfortable and difficult for both the subject and photographer to be at their best. Smaller, cooler and more energyefficient lights have solved this problem to some extent, but the bright lights can still cause the subject to squint their eyes and their pupils to become smaller. This doesn’t occur with a sudden burst of flash as the subject’s eyes don’t have time to react to the bright light, so pupils remain large and flattering. Flash can also freeze motion, such as a dancer leaping into the air. Performing the same task with continuous lights would require extremely bright lights, or a high ISO sensitivity, to allow a fast shutter speed to be used. The former can be very expensive and generate a lot of heat, while the latter can introduce noise into the image.
Traditionally, shooting with tungsten lights requires photographers to compensate for the fact that tungsten light is far ‘warmer’ than daylight. This can be achieved by using a blue filter gel over the light, or by using the appropriate blue lens filter. Tungstenbalanced film is also available, which is specifically designed for use when shooting under tungsten lighting.
Continuous lights can cause the subject to squint and make the pupils smaller. Flash doesn’t produce these effects.
When shooting digital images, white balance is less of an issue provided you aren’t mixing two sources of light. Also, many modern lights are daylight-balanced, which allows them to be mixed with daylight from a window, or sunlight outside, without having to worry too much about mixing light sources of different colour temperatures.
Types of lightning
Where once photographers only had the option of tungsten lighting, continuous lighting now comes in various forms. Each particular lighting technology has its own advantages and disadvantages, and these may have a particular effect depending on the type of photography you wish to use them for.
Fluorescent lights are ideal for shooting portrait, still-life and macro photographs, although standard accessory fittings aren’t common.
Mention fluorescent lights and most people immediately think of the long tubes that are used to illuminate office buildings, but smaller fluorescent lamps and bulbs are now common. These lights work by using electricity to excite mercury vapour, which then emits ultraviolet (UV) light. This UV light then causes a phosphor in the tube or bulb to fluoresce, or glow, which produces visible light.
Fluorescent lights are much more efficient than traditional household tungsten bulbs, and most ‘energysaving light bulbs’ are, in fact, fluorescent. In the past few years, more and more photographic studio lights that use these types of bulbs have come onto the market, and they have very distinct characteristics.
Perhaps the biggest selling point of fluorescent lights is that far less energy is lost as heat. This has led to fluorescent continuous lights often being referred to as ‘cool lights’. The fact that they run cooler than incandescent lights means they are far more practical for shooting portrait, still-life and macro photographs. The lack of heat also means it is possible to use accessories such as softboxes. However, standard accessory fittings aren’t common with these lights, so check what accessories, if any, are available before making a purchase.
Often the bulbs used in photographic cool lights are the same as those used for domestic lighting, except that they use multiple bulbs to achieve a light that is bright enough for photography. For example, the Interfit Super Cool-lite 6 uses six bulbs, which gives the equivalent brightness of a 770W tungsten light. Using so many bulbs also gives some control over the brightness, with the ability to turn each bulb on and off individually.
The colour temperature of fluorescent bulbs can vary greatly depending on the phosphors used. For household applications, bulbs can now be produced with a warm hue, but generally for photographic purposes you will need a cool white or daylightbalanced light. Cool white bulbs have a colour temperature of around 4,100K but daylight-balanced lights rate from 5,000-5,500K and are more useful for photographers. It can also take a few minutes for the bulbs to reach their maximum colour temperature, so it is best to leave them switched on for around 15 minutes prior to shooting.
Fluorescent bulbs last far longer than incandescent bulbs, but as they start to die they may begin to flicker and develop a pink hue.
LED lights have an extremely long life, but can be expensive compared to the brightness of the light produced.
ALTHOUGH light-emitting diodes (LEDs) are not new technology, it is only recently that they have found a use in photographic lighting. They use very little power, which is why we are used to seeing individual LEDs used as small lights to indicate whether an electronic item is on or off. In fact, LEDs are about the most efficient form of lighting when power consumed is compared to light generated. They also have an extremely long life that is far in excess of other types of lighting, meaning that an LED will probably last a lifetime of use. It is for these reasons that LED lights are now used for traffic lights and many external car lights.
However, there are some considerations when LEDs are grouped together and used for photography. The first of these is the expense compared to the brightness of the light produced. A cheap LED light that outputs the equivalent of a traditional 50W tungsten light bulb may cost anywhere between £50 and £300, depending on the technology used. Larger, brighter panels are even more expensive, with a Litepanels 1×1 Standard LED panel costing £1,440 for the equivalent of a 500W tungsten bulb.
Another issue can be the colour temperature of the light output by the LEDs. Premium panels, such as those produced by Litepanels and the relatively inexpensive Manfrotto lights, have a high level of quality control and will use LEDs from a good supplier, so the companies can guarantee the colour accuracy of their lights. The lights produced by these two companies have a colour temperature of 5,600-6,000K, so they are daylight-balanced. Filter gels are even supplied with some lights so they can be mixed with tungsten lights for indoor use.
However, the colour temperature of cheaper LED lights can vary greatly, even from unit to unit. Some of the better lights will also have adjustable power, and again, like other forms of light, the colour temperature can vary throughout the power range – an effect that is minimised on better LED lights. Those planning to use LED lights for shooting video should also take note that some cheaper LED lights can produce a high-frequency flicker that can sometimes be seen in video footage. So while cheaper LEDs have their uses, for best results it is worth spending a few pounds extra.
Of course, this is not to say that there aren’t advantages to using LED lights. The low power consumption means that nearly all panels are battery-powered, which allows them to be recharged. Without the need for mains power, their small size makes them very versatile and they are suitable for mounting on a hotshoe as a portrait fill light or for shooting video. Smaller LED lights are great for macro imagery and also for flower and food photography. They are so efficient that little energy is lost as heat, meaning that flowers will not wilt and frozen food and ice won’t melt quickly.
For entry-level photographers, incandescent lights are the most affordable way to start using continuous lighting.
Incandescent lights work by passing an electric current through a metal, usually tungsten, filament, which is contained within a bulb that is typically filled with either an inert or a halogen gas. Those filled with inert gas are similar to traditional light bulbs used around the home. Halogen lamps have many uses, from household lights and desk lamps to car headlights, outdoor floodlights and work lights.
Incandescent lights are cheap to manufacture and their mass-market use means they are produced in great numbers. However, compared to more modern types of bulb, they are extremely inefficient. Much of the energy that goes into the bulb is released as heat and the brighter the light, the more heat is produced. This waste of energy is one of the reasons why many places, including countries within the EU, are gradually phasing out the household use of some older types of traditional filament bulb. Although in the past most studio photography lights used photoflood tungsten filament bulbs, most lights are now halogen capsules or strip tubes.
While they are relatively inexpensive, the amount of energy wasted as heat is the major problem with this type of lighting. Using a couple of 500W lights in a room over a long period can generate a lot of heat, which can become uncomfortable for both the photographer and the subject. Having a hot, bright light pointing at their face can also make the subject sweat, which is far from flattering when taking portraits.
The heat also causes a problem when it comes to light-modifying accessories. For some types of light, only barn doors and metal snoots are available. Items made of plastic, particularly softboxes, can cause the lights to overheat as there is nowhere for the heat to escape and, at worst, the lights can catch fire. This means that other ways of softening and diffusing the light are needed, such as bouncing the light off a wall or placing a sheet of suitable diffusion material a few feet in front of the light.
Many incandescent lights have little in terms of power adjustment. Some use more than one bulb, for example a 650W and a 350W. This gives three different power settings of 1,000W, 650W and 350W. If the brightness of a light cannot be adjusted, it means that it has to be moved further away from the subject to make it appear dimmer. This in turn has an effect on the ‘look’ of the light, as shadows become stronger and more defined.
Colour temperature from incandescent lights can vary greatly and depends on the brightness of the bulb, but generally the light will be around 2,500-3,000K. An important consideration is that the colour temperature can change as the bulb warms up and it can also vary over the lifetime of the bulb. This isn’t too much of a concern if you are shooting with a digital camera and the incandescent light is the sole light source, but it can be problematic if you plan to mix different light sources. If you are trying to match the incandescent light with daylight, then an appropriate colourcorrection (blue) lighting gel should be used. It is important to use a specially designed gel rather than just coloured plastic; gels are designed to withstand the heat produced by the lights and won’t catch fire, although they can become brittle and crack over time.
The main advantage of using incandescent lights is the cost compared to the power output, making them an ideal choice for a first set of continuous lights. However, technological advances mean there are better options available if you are prepared to spend a little more.