How to Make a Flash Diffuser for Macro Photography

In this tutorial we'll go through the steps needed to make a descent diffuser for an external flash. This diffuser aims to be practical as well as easy to put together. While the primary purpose of this diffuser is for macro photography, it can also be used for general purpose photography.

For this tutorial you will need:

• scissors/box cutter
• gaffer tape and clear packing tape
• foam core or core-flute sheet (I used a sheet of 15" x 20" foam core with one side adhesive)
• aluminium foil
• translucent plastic sheet or baking paper (translucent plastic from a document folder was used in this tutorial)
• ruler,
• elastic/rubber bands; and
• glue (optional - only needed if the foam-core or core-flute doesn't contain an adhesive side).

To do this I placed my flash alongside the foam-core sheet and took a couple of photos of the flash going off. I took several photos with another reflective surface above the flash to help determine the angle that I would get the light to reflect where I wanted it to go. I just measured the angle (152°) off the photo.

From this I used the Pythagorean theorem to draw up a plan for the sides of the diffuser. I also used the same technique to work out how wide the flash scattered to get the measurement for the angle (103°) on the top of the diffuser. The measurements for the diffuser I made for my Canon 580 EXII flash can be found in the pictures. However, feel free to draw up your own plans that are more suitable to the flash that you plan on using. It only takes about 10 minutes. You may want to vary the design a little to suit any adjustments you want to make.

NOTE: I used a CAD program to draw up my blueprint and there are some very precise measurements in the drawing. These do not need to be adhered too exactly. If your angles and lengths are out a bit it doesn't really matter.

I used foam-core that I bought from the local stationary shop for my diffuser. One side of the foam-core had an adhesive surface applied to it. To stick the aluminium to the foam-core all that you need to do is peel of the paper coating from the adhesive side and roll out the aluminium onto the surface of the foam-core. If you need to lay down more than one peace of aluminium to cover the foam-core the overlap can be trimmed using the box cutter or a razor blade.

If using core-flute or foam-core without an adhesive surface, then it is a matter of covering the surface in glue and applying the aluminium.

The next step is to cut out the pieces of foam-core to create the diffuser body. I placed the design sheet onto the white side and proceded to use the ruller and box cutter to cut the shapes out of the foam-core.

Once the pieces have been cut out it is a matter of re-joining them with gaffer tape. To do this I created hinges on all the joins by laying the two pieces I was joining together with the aluminium faces touching. I made sure that I ran a finger along the edges of the foam-core to get the gaffer tape to adhere to the edges. Once the gaffer tape is applied and a hinge is created, I laid the join flat and used the clear tape (sealing tape) to reinforce the inside of the hinge (second picture). The clear tape helps creates a strong hinge while still being highly reflective.

Once the frame for the diffuser has been built the next step is to add the diffusing surface. I used a document holder (pictured) for my diffuser. Other options are baking paper or the side of a large plastic container (e.g. large, square milk bottle side).

Trace the shape of the top of the diffuser onto the plastic, allow extra space around the edge so that the diffusing surface is slightly larger than the diffuser frame. Stick the diffuser onto the front edge of the diffuser frame with gaffer tape.

I only attached the translucent plastic to the front edge of the diffuser so that I can "flat-pack" the diffuser when I am not using it (third picture). If you want, you can have the complete diffuser permanently assembled by taping the translucent plastic all the way around. There is also no need to do the hinge joints in the previous step if you decide to make it non-collapsible.

The diffuser is now complete. All that needs to be done is to mount it on the flash and elastic bands used to hold it into place. The elastic bands also hold the translucent sheet in place when assembled (can be seen in the second picture).

When the diffuser is not being used it can be packed flat so that it fits into a camera bag or laptop bag.