Macro Photography with Your Camera's Built-in Flash

With a simple homemade adaptation, your camera's pop-up or built-in flash may be utilized as a very effective light source for many types of macro photography. The diffuser described in this article provides results similar to specialized and expensive ring flash units, but costs virtually nothing, and is not difficult to fabricate. Like ring flash units, it provides a broad lighting pattern that works well over a wide range of macro uses.

 

The Problem with Built-in Flash

There are at least two drawbacks with using the camera's pop-up or built-in flash for macrophotography. The first is that the flash throws a very harsh frontal illumination onto the subject, which is often unflattering. The second difficulty occurs at very close working distances, when the lens is extended to the point where it partially or completely blocks the flash, casting a heavy shadow onto the subject or depriving it of illumination altogether. This effect may be seen in the photo at right, in which the front edge of the lens has cast its own shadow onto the scene. Now, a diffuser placed just above the front edge of the lens will intercept light from the flash and effectively become a new source of lillumination for the subject, at once eliminating the shadowing problem and providing a broader and more pleasing lighting pattern. Roll your mouse cursor over the image at right to see how the interposition of a diffuser as described above has completely altered the result. Not only has the shadow from the lens barrel been completely eliminated, but the harsh shadow cast by the pushpin on the left is also gone.

 

Illuminated by the pop-up flash on my camera, the image at left shows the kind of result you may expect from the diffuser described in this article. Prominent in the photo below is the "fan" of three diffusers I use, although just one will work. The two extra diffusers intercept more of the flash's light output, and produce a broader spread of illumination. These diffusers are very thin, flat, and flexible, taking up very little space in one's camera bag.

 

How to Make a Diffuser

These diffusers are made from sections cut from that very annoying "blister" packaging which entombs so many products these days-- that clear, stiff, plastic packaging that defies all attempts to free the encased product from its determined grip. It has, however, just the properties we're looking for: it's clear and colorless, thin and virtually weightless, stiff enough to stay flat, yet flexible enough to snap over the lens barrel and stay put, and it's free. Of course, there are other workable substitutes. If you don't have any blister packaging lying in your recycle bin, try a plastic milk jug.

Below is a sketch, with dimensions, of the diffuser I use. You might want to alter the dimensions to suit your own requirements. The slit at the bottom allows the diffuser to be snapped in place over the lens barrel. The hole diameter is made just a hair smaller than the diameter of the lens barrel on which it is to fit; this allows the diffuser to grip the lens barrel to prevent slippage.

The slit and the outside shape of the diffuser may be cut with scissors or a utility knife (but don't cut the slit until after you've cut the hole). The hole requires the most attention--too big and the diffuser won't grip the lens barrel; to small and the diffuser will be hard to mount and won't stay flat. I cut the hole using an engineer's dividers, as shown in the photo below right. This is just a compass with two pointed metal ends. You could also use a draftman's compass in which the lead is replaced by a sharpened nail. The sharp ends allow you to repeatedly scribe the plastic until the divider point breaks through to the other side, leaving a perfectly smooth and round hole. Whatever kind of makeshift hole cutter you use, it must be able to firmly hold its setting. To get the diameter just right, make trial cuts on stiff paper and test the fit on your lens. When you're satisfied with the fit, you're ready to cut the hole in the diffuser itself. After the hole is cut, the piece is sprayed with a clear matte finish, such as Krylon. As can be seen in the photo at right, this produces a translucent surface, and where the diffusers overlap, the diffusion effect is greater. A similar effect may be achieved by abrading the plastic with ultra-fine sandpaper.

 

 

 

 

 

 

 

 

 

 

 

 

Using the diffuser

Place the diffuser as close as possible to the front edge of the lens barrel. The short duration of the flash minimizes camera shake and allows you to handhold the camera, which is very convenient when you're chasing insects around the bushes in the park. You may want to experiment with different sizes of diffusers, and perhaps also experiment with the amount of diffusion which is applied to the surface.

To obtain a compelling macro photo, the importance of the background should never be underestimated. One of the characteristics of flash illumination, as opposed to natural lighting, is that a background that is far behind the main subject will receive less light, and may even appear black in the final image. This may be good or bad, depending upon your desired result; the photo below, taken outdoors in the shade, demonstrates this effect.