Having recently received a LumiQuest Softbox III (product page) for my 40th birthday, I ran a few non-scientific tests to determine when it should be used and when it should not be used.
This softbox is much like the larger softboxes that surround studio lights, but is small and made to fit on the head of a hot shoe flash. It’s held on with hook-and-loop fasteners and can be detached and folded flat when not in use.
Its primary effect is to diffuse (spread and soften) the light from the flash.
For my scene, I used my lovely wife Marline, sitting in a rocker-glider chair in our living room, with a sunlit window behind her. Our daughter appears in some of the frames. No interior lights were used.
Camera: Canon EOS 60D
Flash: LumoPro LP160 (mounted on hot shoe)
Lens: Sigma 28mm f/1.8 EX DG Macro
First I recorded a “control” image, not using the flash at all. Because my subject was only backlit by the window and her face was in shadow, I had to bump up the ISO and widen the aperture. It still resulted in a poor exposure. The window was extremely overexposed, while the subject’s face was too dark, not to mention the grain/noise introduced at such a high ISO setting.
Next, I recorded the same scene with direct flash. That is, the flash on the camera was pointed directly at the subject. I dialed down the flash’s power to 1/32. This lit the scene well, as far as exposure goes, but has the downside of harsh shadows (around her chin and arms), not to mention the reflection of the flash in her glasses. There’s a little light falloff where the wall gets more distant (at left).
That’s where the softbox comes in. I attached my new device to the flash and fired again, this time making sure the flash was set at 1/16 power. (The LumiQuest packaging says the softbox will result in light loss of approximately 2 stops, but in my tests it was closer to one and a third stops.) There are still shadows, but they’re less harsh. There’s still a flash reflection in the subject’s glasses, but it’s softer. Also, the color balance changed slightly, introducing more reds/browns and less blue/white. There’s still a little light falloff at left.
Next, I went with my tried-and-true bounce flash method — aiming the flash at the white ceiling (without the softbox) and letting the light splash down evenly into the scene. Because the light spreads out through the entire room and has to travel further to reach the subject, I put the flash at full power for this next image. The light spreads evenly in the scene and the shadows are very soft and even. So far, this is my favorite image of the test:
Lastly, I re-attached the softbox, but still pointed the flash at the ceiling. To counteract the light loss from the softbox, I raised the ISO to 400. To me, this image seemed the most evenly lit of the five in my test. Not only is the light diffused coming from the softbox, but diffuses further when bouncing from the textured white ceiling.
Of the five, the last looks the most natural, and the lighting is the least distracting. While artificial light is often necessary and/or desirable in low light situations, it’s almost always unnatural looking in photos. The purpose of using bounce flash and diffused (softbox) light is to lessen the distracting effect of the light.
In the first image (natural light), the light is distracting because it’s behind the subject, and because it’s far too bright for the rest of the scene. In the next two images, the light is still distracting because of the harsh shadows and reflections, though the image using the softbox was preferable for me. For me, the light is not distracting in the last two images and the last one looks the most natural.
Keep in mind that my conclusions are only for this scene. With differing circumstances, my choices would differ as well.
For example, if the window had been behind the camera instead of behind the subject, I might not have preferred flash at all.
If the ceiling was much higher (like in a gym or hall) or not white (like in many restaurants or clubs), then bounce flash wouldn’t be of any use and I’d prefer the direct flash with softbox attached.
(Related Post: Using Flash: Matching Outdoor & Indoor Exposure)