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Hi Angie, As you know, the high key effect consists mainly of light tones. Generally the background is nearly pure white. So let’s first let’s concentrate on how to construct and light the background. The white background effect usually starts with a white background material however you can use a less than pure white, it’s just more difficult. The main trick is lighting the background uniformly. It’s hard to explain how fast light falls off i.e. weakens with distance and non-uniformity results. To reduce fall off, the background lamp should be place as far as possible from the background. Distance achieves uniformity. Its OK to use two background lamps one left and one right, again distance yields uniformity. If the area is big enough you can back light the background material. Distance, lamp to background, is both friend and foe. Far gains uniformity but you suffer light loss. Given modern software fixes, better to light evenly and get a uniform non-white. You can fix and enhance with the common tools available in your graphics software. Lighting the subject:
Shadows on the background are your adversary however, high key requires shadows for modeling that are achieved by placing the main light high to simulate the sun. Usually the main is set off to one side, this achieves the necessary modeling shadows. You don’t want these shadows to be too harsh so you soften them with a fill light. Fill light:
It’s a major blunder to fail to understand that you always fill from the cameras prospective. This means placing the fill at camera height near an imagined line stretched between camera lens and subject. Fill is placed just far enough off this line to avoid it getting into the picture. Fill can also be placed above and behind the camera but not too high. In any event, move fill up down or side to side at will just far enough to avoid casting equipment shadows on background or on the subject. Lighting ratio:
High key requires a lighting ratio not to exceed 3:1. This is achieved by making sure the fill light arrives at the subject, subordinate to the main. It should be ½ the main’s intensity or stated in f/stops, 1 f stop less brilliant. Measure each for intensity independently with the all others off. Again, set the main one stop brighter than the fill. If unable to meter, use lamps of equal brilliance. Measure the main to subject distance in feet. Place fill 1.4 times more distant. Example main at 8 feet fill at 11 feet. This achieves the needed 3:1 ratio. For high key less than 3:1 is acceptable but not 2:1 which too flat. Two equal lamps placed at the same distance = 2:1 which is a no no for high key. Exposure is base on a reading taken with only the fill illuminating the subject. I know some will find fault with this account. That’s OK. Maybe you should just chuckle at my piece and pay it no mind.
Good luck, Alan Marcus
ammarcus@earthlink.net
September 17, 2006
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