Monday, March 1, 2004
Tame Lighting Extremes
Nature often serves us splendid scenes, but with light that won‚’t cooperate with our camera‚’s and film‚’s abilities. Here‚’s how to bring those conditions under control.
Graduated filters don't have to be reserved for the sky; they can be used for any situation where the lighting contrast is high. Examples include putting the ND section over intense snow next to a pine forest, using the dark part of the filter to knock down the sun's reflections in water, or moving the ND area over the brightest part of a slot canyon. No matter how you use them, these filters help you to compose a photograph that just won't happen any other way.
How to expose? Most of the time, you can use your evaluative or matrix-type metering system and you'll get a decent exposure. Bracketing can help, and, of course, with a digital camera, you can check to be sure you got the right exposure on your LCD monitor.
Beyond that, the best thing to do is get out and experiment. This is one filter that I always keep with me, even now that I shoot mostly digital. It's so easy to use that it's worth a try in many situations where you have extreme brightness conditions.
Fill-flash does exactly what the technique's name suggests—it fills your subject's shadows with light from a flash unit. Without a fill light, shadows in high-contrast situations would record as empty black holes. In the past, fill-flash was considered a professional technique because of the complexity of the technical issues involved, but modern photographic equipment has made it simple for everyone. Your equipment will calculate exposure for two light sources, your flash and the ambient light, and arrive at settings that balance the two.
Fill-flash works well for objects within a moderate range (you might light a boulder or a small tree, but not a canyon or a mountain). More powerful, accessory flash gives more options for fill-flash. For dramatic photos, use flash at sunset to fill in the immediate foreground to balance the glowing sky.
You can start using this technique with any camera that has a built-in flash. If you're using a compact digital camera, go through your camera's flash modes until you get to the flash-on setting (the name changes, depending on camera model). The setting will cause your flash to fire even though there's plenty of light to make the photo without it. If your camera offers Scene modes, you also can try "Slow Sync" or "Night Portrait."
Some 35mm and digital SLRs also have a built-in flash. Popping up the flash tells the camera you'd like to use it, and your camera will work the flash into its exposure calculations automatically. Generally, little more is required from you when it's bright outside.
When the ambient light becomes dimmer, your camera may keep the shutter speeds in a handholdable range for some modes, which will allow the background to go dark. The fix depends on the camera; for many, you can use shutter-priority auto-exposure and set a slow shutter speed for the dimmer ambient conditions. Some cameras will keep giving proper ambient light exposures when you choose aperture-priority exposure. Slow-Sync and Night Portrait settings are sometimes available on these cameras and will often balance ambient and flash light quite well.
You do have to consider how much flash fill you want. If the light outside is coming from behind your subject, creating a silhouette, give your flash the full normal exposure.
If sunlight is falling directly on your subject, causing small pockets of shadows, then filling in the shadows completely will ruin the three-dimensional quality of the light. Try reducing your flash's output by a stop. This dimmer fill still opens up the shadows so they don't record as empty black pockets, but preserves the character of the lighting. For more dramatic results with even less fill, try -1 1/2 or -2 stops.
Your camera's metering system may well give you nicely balanced light automatically. Experiment beforehand so you'll develop a feel for how everything works. When using digital, rely on your camera's LCD monitor to double-check that your camera's settings give you a balance of light that you like.
Keep the range of your flash in mind. The range varies according to model, but in bright sunlight, assume it's no more than five to 10 feet for most built-in flash units, with the more powerful hot-shoe-mounted strobes reaching perhaps 15 feet. For all flash units, the fill range increases as the amount of sunlight decreases (it's easier for the flash to match the lower light level), so you'll have better fill-flash range as sunset approaches.
If you shoot with a telephoto, some of the flash beam is wasted as it spreads out to cover the field of a wide-angle lens. Many hot-shoe-mounted flash units have a zoom system that extends flash range by concentrating the beam into a telephoto's narrower field. For very long telephotos, 300mm or longer, aftermarket Fresnel condensing lenses are available to fit over the front of your external flash. Project-A-Flash (www.leppphoto.com) and Flashextender (www.rue.com) will both focus your flash's light even more than your flash's zoom head and can extend flash range by more than 200%.
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