Using Continuous Lighting for Photography
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As we look at lighting options for photography, we are directed either to flash or continuous light. For years, flash has been the choice of professionals because of its controllability, output variability and power. As creatives embrace more video (you are out there, somewhere…) the consideration of using continuous lighting is increasing. This time we will look at options today for continuous lighting for photography.
Lighting Types
There are a number of options for continuous light photography.
Incandescent
These are the classic bulb type lights. They typically have a fixture that mounts on a stand that holds a reflective bowl and the bulb. They have fallen out of favour because of power demands, the necessity for AC power and the amount of heat that they generate. Colour temperature is fairly consistent in the tungsten range of about 3200K. They are extremely bright however and allow for smaller apertures at reasonable shutter speeds. Finding replacement bulbs is becoming problematic.
Fluorescent
About 15 years ago, vendors started using fluorescents for continuous lights. The initial foray used fluorescant tube type lights. Tubes demanded less power and the right tubes produced a fair bit of light, allowing for reasonable depth of field options at handholdable shutter speeds. The challenge was consistency in colour temperature and dealing with the flickering common to fluorescents. The Kino Flo company addressed this with specially designed fixtures and specific tubes that held colour temperature and managed the flickering. I still have Kino Flo setups in my studio and they still work great, although sourcing the tubes is more challenging. Of course fluorescent tubes are very fragile and if broken the dust is toxic, so care must be taken. Next came more traditional fixtures that used the curlicue style fluorescent bulbs. While easier to mount anywhere, and with more consistent colour temperature control, flicker remained an issue and while they use considerably less power than incandescent, they also put out less light, requiring much longer shutter open times to have the same depth of field as a similar incandescent. This made them less useful for subjects that move.
LEDs
Today we see LED lighting in numerous forms. Fluorescent screw in bulbs are pretty much gone, which is a good thing from an environmental perspective. LEDs are more stable, hold colour temperature very well and are relatively inexpensive. The challenge is output with most LED bulbs not delivering much output and when the subject is even a medium distance away, shutter speeds drop to allow for acceptable depth of field. The video format of choice are LED panels. While there are single LED systems, they are, to be fair, useless for photography other than macro work where you can put the light inches away from the subject. They look very bright, but really don’t deliver all that much light at working distances. When you gang a number of single LEDs into a single panel however, you can get a pretty good amount of light from a panel if the panel has enough LEDs. Small panels are fine for small subjects or supplemental lighting but if a panel will be your primary light source, you want larger panels. The availability of light shaping tools is limited to barn doors and scrims for panels, so more photo oriented light shapers like octas and paras do not exist at this time. There are LED powered units that look like strobes, but the issue with them is cost (high) and output (low). If your subject is not moving, they can be perfect.
Benefits of Continuous Lighting for Photography
The big benefit is what you see is what you get. When you use continuous light, you see what the camera sees through the viewfinder or on the LCD or in the EVF. This allows for time savings in positioning and placement up front so once the lights are in place, you can get on with the shooting. As with any kind of lighting you must remember the inverse square law because if your light to subject distance increases, the light falls off at the square of the distance change. Still for people learning to light, continuous lighting is a great tool.
Downsides of Continuous Lighting for Photography
Output level is the big downside of continuous lighting. Unless you are using cinema grade HMI continuous lights, which I have not covered because they are too expensive and too cumbersome for regular use and often require special power, continuous lights can never deliver the same amount of light as a flash or strobe in the same size package. If you are a fan of light shaping tools, particularly octaboxes, big softboxes and parabolics, you may find that options of these for continuous lights are limited to continuous lights built to the specifications of a strobe system. Because there is less power to start with even using scrims and umbrellas can be a challenge in terms of depth of field and handholdable shutter speeds, unless you can get the lights in really tight.
Closing Thoughts
You have more options for continuous lighting for photography than ever before and it is no longer a no go zone for some subjects. With enough LEDs in a panel, you can even use continous light for live subjects that you can exercise some control over such as headshots and portraits and even family work. Pets can still be a problem if they will not sit still, so consider your particular subjects in advance.
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