Deconstructing light, part four: continuous sources

The final part in this introduction to lighting mini-series is a look at when continuous light sources can be useful, and how to best deploy them.

I use continuous lighting primarily for food photography – specifically, large, high-CRI LED panels – because the low temperature of the source doesn’t interfere with the subject. (Try blasting sashimi with flash repeatedly, and you’ll soon see just how fast delicate fish can cook.) However, it’s also useful in other situations – obviously, to give clients an idea of what the end result will look like; for videography, when flashes obviously aren’t feasible, and less obviously, when you’re working in a dark environment and actually need a reasonably accurate representation of what the light will look like in order to compose and focus.

The rules for using continuous lights are pretty much the same, but with a few limitations:
1. Color temperature usually isn’t variable, and for large sources, you might not be able to find gels big enough – so you will probably have to go with almost 100% artificial light in your exposure. Note that you can also find continuous tungsten lights, but these run very hot and have a very low color temperature, which can lead to problems with blues.
2. LED panels aren’t that bright, so you will need to work with a tripod, and again, watch ambient light – it will creep in because the exposure times will necessarily be longer than for flash photography.
3. Subject motion – another consequence of longer exposures, especially with human subjects.
4. Heat. If you’re using tungsten light, be careful with things accidentally coming in contact with the bulbs or heads and catching fire or burning. That includes your skin.
5. Power. You’ll need to be plugged into mains or large batteries for lights of any consequential power. Ensure you take this into account when planning for a shoot – extension cables and power strips are your friend!

Let’s look at some examples, shall we?

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The end of sorbet. Leica D-Lux 5

Single small LED panel to the top; note the hot spot on the spoon. The problem with using panels is that they’re difficult diffuse without a significant loss in power; the only way to make it work is either live with the hot spots (not a major problem for food) or get bigger panels (very expensive). I wanted my panels to be versatile, so I’m now using 45x45cm models.

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Test shot from the M-Monochrom review. Leica M-Monochrom, 50/2 APO

One large LED panel off to the right; since it was a test shot, I didn’t bother to clear the wire from the foreground…with human subjects, LED panels enable faster, more comfortable working as you don’t have to make as many trial and error adjustments with the flash, and it’s simply not as hot.

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Bread. Leica D-Lux 5

Part of a series from a food photography class I ran for Leica earlier in the year. I had two small LED panels for this, spread out around the top of the image and on even power; they provided definition and shadow. Image was shot top-down, obviously.

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Foie gras. Leica D-Lux 5

Two LED panels; one top left, one top right. Both slightly above the subject to highlight that moisty, oily sheen on the seared foie gras. LED panels are quite directional but yet with short throw; this means they’ve got to be fairly close to your subject, and you’ll need more than one to fill in the shadows.

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Leica S2, using the D-Lux 5

This is an example of what you can do when you have 40 LED panels at your disposal – I demonstrated product photography using the mini-panels to create a ring of light around the subject, with some actually providing light on the subject, and some just there to provide background texture.

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Sushi platter. Leica D-Lux 5

One medium panel from the top took care of lighting here – getting the height and angle right is the critical part, so that the subject is evenly lit but yet has definition to preserve the shape and texture of the fish. Panels were about 30cm above the subject in this case.

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Rice cones. Olympus OM-D

I used two panels here – one on full power from the right side, slightly elevated relative to the plane of the plate, and slightly behind; the other was to the left and running 1/8th power to provide fill and keep the food looking fresh and ‘bright’ rather than shadowy and ‘heavy’. Lighting is all about psychology and creating the desired mood in the viewer…

A primer on lighting equipment is here. Part one on single sources can be found here; part two on multiple sources, here; part three on balancing ambient, here.

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