Photography News | Issue 33 | absolutephoto.com
19
Technique
ISO 100 and test-firing the flash at various powers until it gave me an f/16 reading (the same as the camera) at just under full power. From this point on you can shoot away and the effect will work fine, but there are some things to watch out for. Flash position and angle is one of them, as mentioned above. I first placed one light (an Interfit S1 head) fitted with a softbox, directly above Mabel’s position, pointing downwards, but the light was a bit flat and I decided to use two flashes instead, one from either side. This meant repositioning the first light and checking its power again. Once satisfied I put in the second light, fitting it with a simple spill-kill reflector and pointing it in from behind, then set the power as before. The cross-lighting worked well, giving a little halo to Mabel’s coat, but the first light with the softbox was now spilling onto the background. To fix this, I turned its position, rotating it away from the backdrop, so it wouldn’t spread there. Due to theway the light spreads from it, a softbox makes this more difficult, so if you’re having similar trouble, consider fitting your softbox with a grid to narrow the light. Side lighting generally looks effective with a black background anyway. Alternatively, try switching to a beauty dish, or using a spill-kill with a diffuser panel. Of course, whatever modifier you use, if you shoot the subject full length you’ll light the background around their feet, so for a cleaner look, try cropping to head and shoulders or a half-length competition. With these minor issues sorted I was free to shoot at will, the only other concern being changes in the ambient light. It’s not an issue if it gets darker, as the flashwill remain constant, but if conditions get lighter, you’ll need to reassess the exposure for the ambient light, making sure the background is still dark. If you use a sufficiently fast shutter speed, the ambient light will not be recorded, but the flash will Black backgrounds vs full-length framing There’s nothing to stop you from shooting your subject full length using this technique, and pics can still look striking, thanks to the inherent contrast and the simplicity of the black backdrop. However, you will find that it’s impossible to create a fully black background that way, the reason being that there will inevitably be some spill of the light from the flash which shows up the environment around their standing position, or anywhere that they make contact with the ground. By angling the light further away from the subject, the effect can be feathered, as shown on the left, so the illumination will drop away in intensity towards their feet. But the only way to ensure a completely black backdrop using this technique is to crop in and frame the subject so that it’s a classic portrait head and shoulders or half- length composition. In the examples on the left, a single light was used, fitted with a large softbox and angled down on the subject from above.
Howflashworks with shutter speed
Regular exposure
Black backdrop
One of the fundamental principles of flash photography is that the brightness of the flash is not affected by the shutter speed you use. You can see this clearly in the examples here; the flash power remains the same, as do the aperture (f/16) and ISO (100) settings, but the shutter speed is varied between 1/4sec and 1/125sec. Notice how the background darkens and the shadows on the opposite side of the flash’s direction deepen as the shutter speed shortens. As the shutter quickens less ambient light is recorded, so eventually it’s mostly the flash that lights the subject. The effect is cumulative though, so if too much ambient light is recorded along with the flash, areas struck by the flash will overexpose, like the toe of the boot. The only times that shutter speed directly affects flash is when the shutter speed is too high and sync errors are encountered, or if you’re using high-speed flash which behaves differently from regular flash lighting.
1/4sec
sync speed the camera allowed – 1/250sec on the Nikon D800 I was using. ISO was set to its lowest (100). This is the same for most cameras, but some go to 50 or lower; you can use the expanded settings if necessary (called Lo or (L)), but be aware that this can affect the dynamic range and image quality, so the ‘native’ range should be stuck to if possible. Finally, I closed the aperture; trying first f/11, then working down before finally getting to f/16. You don’t want to close the aperture more than you have to, to f/22 or f/32 for example, as smaller apertures will affect the sharpness of the image. Here, f/16 was fine. When I shot, it was a cloudy day, but still reasonably bright at noon, and a check of the histogram showed the exposure was dark enough, with the graph firmly clumped to
the left. It’s best to check the histogram, as pics can look dark, but will actually still have plenty of background on show. If you reach the limits of ISO, aperture and shutter speed and the exposure still isn’t dark enough, as it may be on very sunny days, consider shooting in a shadier area, or fitting anND filter whichwill block some of the light; unfortunately an ND will also block the flash, so it’s a last resort and waiting for dimmer conditions is preferable. Flash placement and power Next comes the flash power. Using a flash meter, or alternatively by checking your exposures on screen, increase the flash power until the exposure on the subject is good. I used a Gossen DigiPro F2 meter, setting it to
1/8sec
1/15sec
1/30sec
1/60sec
1/125sec
Settings The key is to set an exposure that won’t record the available light, just the flash. This means setting the camera’s maximum sync speed, a low ISO and closing the aperture. To asses the darkness of the background, shoot and check the histogram.
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