HIWS: Double Diffusion for Reflective Subjects

Domed flash through diffuser

Whenever my wife asks me to shoot some product photography for her blog, I jump at the chance. It’s a fun way to experiment with lighting, and this time I decided to try out some double diffusion.

Shiny and/or reflective objects can be a real pain to photograph because they tend to pick up every reflection in the room. When using flash it gets even worse because the object will show the reflection of the flash as a bright specular highlight. The smaller your apparent light source, the smaller the specular highlight on the object. Even a fairly large light source will not always give you the look you are trying to achieve, and forget about trying to hide the ribs of an umbrella in a reflective object!

The problem is that, while an apparently large light source will provide soft light, the actual light source itself will be reflected on the shiny surface. In addition, the edges of the specular highlight will have hard transitions to the rest of the surface. In order to achieve smoother transitions from the specular highlight, you have to double diffuse. Or have frosted glass, which I sort of had with the amount of condensation on these bottles.

To demonstrate, let’s look at examples of the product shots I took for my wife’s blog. I’m not actually happy with the angle of the shot so I’ll probably redo it anyway, but these photos demonstrate the concept of double diffusion fairly well.

Bare flash
Bare flash

DSC_1657
Setup: bare flash
To begin, above is a shot with a bare speedlight as the light source. As you would expect with a hard light source, you get harsh shadows and a small bright specular highlight on both of the glass containers. If you don’t know what a specular highlight is, it’s the almost pure white highlight on the lids and upper portions of the containers. This highlight actually would have been harsher had there not been so much condensation on the bottles.

Bare flash through diffuser
Bare flash through diffuser
In this next shot, I added a large diffusion panel. This softens the light considerably as the speedlight is now turning the diffusion panel into a giant light source, in comparison to the size of the products. You can see how the shadows have softer transitions, as do the specular highlights.

Domed flash through diffuser
Domed flash through diffuser

Setup: Domed flash through diffuser
Setup: Domed flash through diffuser
Next, I added a dome diffuser to the speedlight and shot that through the diffusion panel. You’ll notice that the shadows have even softer transitions here, but most importantly, so do the specular highlights. Those highlights look silky smooth and blend in subtly with the rest of the bottles. Boom: double diffusion. The trick is in having the light that’s hitting the diffusion panel be diffused itself. This helps the light to be more even on the diffusion panel which makes its reflection appear more even in the specular highlights.

Setup: Side of domed flash through diffuser
Setup: Side of domed flash through diffuser
I decided to do a little experiment next. I had the domed speedlight aiming directly at the diffusion panel. What if I were to aim it directly up so that the light had a chance to bounce off the top of the dome first, travel through the side of the dome, and then through the diffusion panel? In order to keep light from spilling through the top of the dome, I put a folded black bag on it. The shot is below:

Side of domed flash through diffuser
Side of domed flash through diffuser
Even softer sure, but the light was a little too flat for my taste. Regardless, it’s important to experiment in order to see what works and what doesn’t.

Well, it’s back to the studio—um, living room floor—for me. I’ll try to get a lower angle this time, and maybe attach that diffuser to a lightstand so I don’t have to hold it!

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