Dean Collins invented ‘cromazones’ – predictable, variable studio backdrop color from a gel-filtered background light. David Kilpatrick sets out to show how two low-cost strobes switchable down to quarter power give all the control you need.We used Elinchrom EL250 and EL500 mains powered studio flash-heads. An Elinchrom Mini Optical Spot unit was used on the main light. The background light used red filter gel and a diffusing scrim. The seamless paper was black Colorama. Minolta 9000, 100mm f2.8 AF Macro, Fujichrome Provia 100. This article was originally prepared in 1995 for our first ever photo website and used images carefully trimmed in size to save bandwidth!
Zone Zero – plain black
Main light thru the Spot is the EL 500 at full power 500Ws. The incident light aperture reading using a Minolta Flashmeter IV is f11. There is no background light. To get a threshold trace of backdrop color, a red-gelled EL 250 at minimum power (64Ws) was moved until incident light on the black seamless paper was 2 stops less (f5.6). If you don’t see a change below, your monitor is set too dark or contrasty.
A trace of color
This hardly-visible trace of color is from the background flash at 64Ws, main light 500Ws. You’ll see a clear increase in background color in the next shot, where the background light (positioned on the floor under the subject shooting table) is turned up to half power – 125ws.
Rich dense color
For dark, dense color the background flash is at 125Ws half power, and the backdrop incident light reading is f8, one stop less than the main spotlight. The seamless paper is pure black at the top. This the lowest setting you’ll find useful in practice.
Pure deep color
With the background light up at full power (incident reading f11 same as main spot light) the color of the gel shows clearly, remaining deep, with a strong gradation to black. To widen the ratio between main (500Ws) and background (250Ws) light we now swap them over.
The main spot light is now the EL 250 at full power with the lens opened up to f8. The background EL 500 head is at half power, 250Ws (f11). The result is pure strong color grading to dark gray at the top. We now have two stops further available main light power reduction, one stop further background boost.
The main light stays at 250Ws, camera set to f8; the background light is turned up to full 500Ws (f16). The result is saturated color with some remaining gradation in the background. The tiles now have a trace of reflected color. To adjust further, wider lens apertures will be needed.
Maximum color saturation
The main light is reduced to half power, 125Ws. The aperture set is now f5.6. The background light is at full power 500Ws, incident light reading f16. The saturated color burns out to pure ’emulsion layer’ red. The tiles have started to reflect color. The two small flash units now allow one step further by opening up to an unreasonably wide f4…
Color floods over
The aperture is now f4 and depth of field only just adequate, with the main spot turned down to 64Ws, quarter power. Red now floods the reflective tiles. Saturation in the center of the color zone is reduced, no backdrop gradation remains, but the black subject stays clean in our mid-grey painted studio.
Test your own setup on slide film, neg film or digital – which is likely to show a greater difference and may show may change in colour. Record your readings or settings so predictable color backgrounds can be created in future.