A light cone is a great accessory for any tabletop photography where wrap-around diffusion is needed. This is especially useful for photographing shiny reflective metallic surfaces. The camera lens is placed on the small open end of the cone and allows one to shoot down at the subject. Professional light cones made of acrylic can cost several hundred dollars; here is a DIY solution
that is simple and economical.
Get some Mylar
Purchase a sheet of Mylar, 24 x 36 inches from any art supply store (costs about $5.00).
Do some math online
We found Craig Russell’s blog calculator really helpful for measurements for the pattern to construct a flat top cone. craig-russell.co.uk/demos/cone_calculator
Decide how big you want the cone — the limit here is the size of the Mylar sheet. Choose a diameter for the top, bottom, and height to accommodate the objects you plan on photographing.
Enter lengths A, B, and C into the calculator, click on “Calculate,” and the program will generate the arc angle and radii R1, R2. For the sample shown here, A=100 mm, B=380
mm, and C=380 mm. Output from the calculator gave an arc angle of 124.5 degrees, R1=144.6 mm, and R2=550 mm.
Tape the sheet of mylar to a table and draw in the measurements
Measure the arc angle with a protractor and draw R1 and R2 using a straight edge.
A string stretched tight with one end anchored at the vertex and the other tied to a pencil can be used to draw the arcs.
Cut out the pattern.
Place tape on one open edge and close to form the cone.
When you’re done, unlike a professional cone, the tape can be removed and the cone can revert to its flat shape for easy storage.
All that you have left to do is to find a suitable background material (seamless paper works well), set up your lights, place the lens at the opening and shoot. To steady your shot, use a tripod with the column reversed.
Soon, you will be looking everywhere for shiny metallic objects to photograph!