I recently wrote about budget barndoors for your lights. Today I want to show the first of two ways to simulate spot light effects on a budget. Both methods use one strobe head. While you could possibly do these effects with speedlights, having a strobe head with a modeling lamp in it is much easier as you can see what you are doing. **This post contains affiliate links and I will be compensated if you make a purchase after clicking on my links.
Today's method has a single strobe head with a standard 7" reflector dish off about 45-degrees to the left of the camera and pointing straight at the subject. In between the light and the subject is a 20"x30" sheet of black foamcore with a 9"x2" hole cut out of the middle of it acting as a gobo (short for Go-Between, something that goes between the light and the subject to modify the light). You can vary the size and shape of the hole to suit the effect you are going for. You can control the edge of the effect by the placement of the light and the foamcore. The closer the foamcore with its aperture is to the subject, the more defined the shadow will be. I know I always have to stop for a second to think this through. A way to remember it is to think of the sun as your source of light and the difference in shadow from an airplane crossing in front of the sun (soft edge, barely noticeable shadow) and the shadow cast by a street sign a few feet away from you (hard edged, well defined shadow). For the image to the right, the strobe head was about 5 feet away from the subject and the foamcore was a few inches away from the subject, almost coming into the frame.
In the second image, I placed a red theatrical gel** over the light for a different effect. Note that the gel is on the lamp, not on the slit in the foamcore. If the gel was on the slit, the white light from the strobe head would dilute the color as it bounced around the room.
Small sheets of foamcore or heavy-duty black card stock should be available locally at arts & crafts stores, department stores, sign shops, art supply stores, etc. Attach the board to a light stand using spring clamps. Another option is to use Cinefoil** instead of foamcore. Cinefoil is a heavy duty black aluminum foil that can be easily shaped and cut and can be used as here as a gobo, or you can make a snoot or barn doors.
Below is a photograph of the black foamcore with the hole cut out and a utility knife for scale. Below that is the lighting diagram for the example photos shown above.