To emulate sunset lighting, I find it’s easiest to use a handheld strobe positioned on a stand, well off the camera axis and at or above the subject’s eye level. I trigger my strobes when used this way via a PocketWizard, but you could certainly use other flash triggers. Heck, when I learned this technique 20 years ago, we used off-camera flashes with hardwired PC connections made from extension cords—an approach that still works fine today.
To start, make sure the subject isn’t in direct sunlight; either open shade or choosing a lightly overcast day will suffice. Otherwise, you’ll end up with two competing key lights, and that looks natural to no one. With the subject in place, I position the strobe fairly far from the subject and approximately at eye level—too low and the shadows will be unflattering and somewhat unrealistic. In the case of the portrait here, the strobe was about 15 feet to the left of the subject. The farther away the light source is, the less immediate the light falloff is. And, since the sun is far away (producing minimal falloff), it’s best to approximate this by putting your light as far as possible from your subject.
Next, I attached an orange gel—in this case, a CTO (color temperature orange)—taped over the flash. You can even double up the gel to get a deeper, richer orange color, but beware that it will cut the intensity of the light, as well.
I prefer to use manual flash power and manual exposure. Given the distance from the subject, I knew I’d need all the power my flash could provide. So, I put it in manual mode and full power. I then adjusted my camera’s manual exposure to slightly underexpose the ambient light. In this case, the ambient exposure was 1/80th at ƒ/4, so I shot with the flash at 1/125th at ƒ/4. This ensures the flash will be responsible for most of the exposure and make it look more like real sunset light.
I next tested the flash exposure. I could have simply dialed it down if it was too bright, or adjusted the aperture from ƒ/4 to ƒ/2.8 if it was too dark. (I would then have to compensate with a faster shutter speed, as well. And, if I bumped up against the 1/250th sync limit, I would simply move the flash a bit closer until its full power provided enough illumination.)
With the ambient exposure and the flash dialed in, now it’s all about getting the model in just the right position, where the flash will still appear as a low-angle magic hour light, but where it’s also flattering on the her face. If it’s too low, it can look like monster lighting, or just generally unappealing as nose shadows fall up toward the eye. This is true of almost any subject—even when it’s not a person. Light from below is simply unnatural. To avoid this, I simply raise the flash until it’s just a bit above eye level. This way it’s low enough but still hitting the subject’s face from pleasing angles. Then you can simply readjust the subject’s pose—in particular, the head tilt and position—until the light is falling in a flattering manner exactly how you want it.
One thing you can also try is to put the orange-gelled strobe close to or actually in the frame at the corner of the scene. In this way, it will cause creative lens flare and give the whole image an overall orange glow. Take a look at the shot of the gelled flash above; that’s straight out of the camera. That orange glow can help enhance the feeling of sunset as long as you don’t mind the reduced contrast and clarity that come with flare. You can also enhance this tint, or even give your picture a stronger orange glow, by editing the image in Lightroom or Photoshop. In Lightroom, I gravitate toward the color slider, where I simply grab the orange slider, and maybe even the red and yellow sliders, and dial up the golden glow and its saturation. If you don’t have any orange gels on hand, you can always use this approach to try to emulate the effect in post. It’s not a bad idea, and it can be done well, but it lacks the specular quality and direction that come from actually using a gelled flash in front of the camera.