In many circles, new technologies are challenging traditional staples of photography from different directions. For cameras, mirrorless camera systems are making great strides and beginning to challenge full frame and APS-C DSLRs’ supremacy as the only type of camera for “serious” photographers. Likewise, continuous lighting, most often fluorescent or LED sources, is seizing market share from the champions-of-old, hot shoe flash and strobes. In the series to follow, I will discuss several distinct advantages of flash light sources over continuous sources.
Fair warning: this part may get a bit technical. Flash can, effectually, be much more powerful than continuous lighting. A significant reason for this capacity is that adding flash essentially adds a second exposure. Because the full output of the flash is discharged in an instant (one or two caveats here in regards to speedlights), the full effect of the flash can be recorded in the same way regardless of shutter speed, provided the shutter speed selected is the camera’s x-synch speed or below. Since ambient light is continuous, the cameras shutter speed can be used to reduce the ambient exposure while the flash exposure remains unchanged, enabling a small flash to effectively “overpower” powerful ambient light sources.
For the amount of power deliverable, flash is nearly always more compact and portable. Portable continuous sources can get to several hundred watts of equivalent power. Not bad, but flash can do that and more at any shutter speed. A small hotshoe flash can output power more effectively than can a larger continuous light. There are certainly large mains-powered strobes which have limited mobility, but there are very portable options in the speedlite category. Battery powered systems can bring the power advantages of powerful strobes on the road.
Nicer continuous sources are often fully dimable. The disadvantages are that there are frequently color temperature shifts or flicker when dimming all but high end models. For video, constant lighting’s domain, such issues may not always be as readily evident. But for photography, flash’s advantages of being able to output a range of power from full often down to 1/128 with consistent color rendering are exceedingly helpful.
Constant lighting has its place. Video simply is not possible with flash; and applications which require very low power output favor continuous lighting. Flash has many advantages which make learning its arts very valuable to photographers. On models without modeling lights, one does not have the “WYSIWYG” convenience, but flash’s advantages are many.
More to come.
Boyd Johnson is a portrait and editorial photographer based in Hickory, N.C. Together with his wife Gabby, he runs B&G Photography.