DigitalCameraReview.com
Light Modifiers: An Analysis and Field Guide
by David Rasnake -  2/29/2008

True confessions time: I'm a soft target for camera accessory advertisements. It doesn't take much more than a few flashy product shots to convince me that the $30 gizmo of the week is going to change my photographic life. Perhaps thankfully, reality tends to set in pretty quickly – sometimes even before I pull the trigger on a purchase. Still, this hasn't kept me from amassing a bagful of small accessories of varying usefulness, and over the years I've been especially drawn to accessories promising better flash pictures.

Even with good equipment and experience, flash shooting can be tricky. A DSLR with an external flash unit, especially one with a tilt/swivel head, is capable, in the right hands, of providing illumination that has little in common with the blasted, flat look that point-and-shoot users often associate with flash photos. Even with this kind of setup, however, being able to further soften the light coming from your flash unit is often crucial to getting a nice, evenly exposed shot. In order to make this happen, photographers must go wading into one of the advertising minefield described above: the dangerous, often over-hyped world of light modifiers.


THE DIFFUSER

Most basically, a light modifier is anything that alters the light coming from your flash unit. In general, accessory light modifiers are designed to work with hot-shoe mounted external flash units for DSLRs, though there are modifiers for DSLR pop-up flashes, and even systems for built-in flashes on compact cameras. Photographers needing softer, more even flash photos look to a specific group of light modifiers known as diffusers – accessories designed to spread light from the flash out more evenly and prevent the overexposed, flattened look of typical flash photos.

The most basic form of diffusion is to use a tilting-head flash, which allows the head of the unit to be pointed upward, to bounce light off of the ceiling (or an index card taped to the flash itself, or both) and back down onto the subject. Several accessories promise similar or even better results than this basic method, working in conjunction with external flash units to get light up, out, and evenly dispersed. Many systems are also designed to provide bounce-like results outdoors, in rooms with high ceilings, or anywhere else that traditional flash bouncing isn't an option.

With all of the products out there (and in my camera bag), it seemed worth our time to give a few of the available options a more thorough review. Working with experienced wedding photographer, NotebookReview.com editor, and flash photography guru Jerry Jackson, we've put together a group of light modifiers representing a few different approaches to flash diffusion.

Light Modifiers

Given that most diffuser manufacturers promise noticeable improvements when using their product, and that both Jerry and I have purchased more than our fair share of these products promising flash photo perfection in the past, we were interested to find out how well each of these diffusers performed under normal flash-photo shooting conditions, and how they stacked up in some controlled, side-by-side testing.

Jerry and I both knew what we believed to be true about our favorite (and least favorite) products in the bunch, but we didn't entirely know what to expect from a controlled test. Would there be any discernible difference between the various products? Would any of them improve the shots as much as promised? Would the more elaborate, expensive, and outlandish looking systems really perform better than the simplest solutions? There was only one way to find out...


THE METHODOLOGY

Coming up with an accurate testing methodology was a point of some debate and long consideration. Our aim in testing the modifiers was two-fold: first, to see how much they actually did to change the amount or distribution of light from the flash. (We had a hunch that a few of the modifiers in our test weren't really serving as much other than flash unit fashion accessories.) Because the P-TTL flash metering system used on our Pentax K10D test setup, and similar through-the-lens flash systems on DSLRs from other manufacturers, actively and automatically modify the light output of flash units to achieve correct exposure, it would be hard, given the variable light output from these P-TTL flash units, to determine what (if any) effect the light modifier was actually having.

To answer this need and give us some control shots for analysis, we fell back on a test setup using the Vivitar 283, a classic workhorse flash that, with our model's installed "Varipower" module, allows full manual control over light output.

Flashes

At the same time, many users have migrated to the current generation of metered flash systems, which automatically assure correct exposure in most cases with almost no user input. In some ways, then, in the interest of real world testing it was more important to see how the flash modifiers performed when the camera was left to its own devices. Hence, we opted to shoot the same battery of shots with the same light modifiers using a current P-TTL flash unit - in this case, the Pentax AF-360FGZ.

Flashes

In each case, default flash settings without power compensation were used unless otherwise noted. For control shots with the Vivitar flash, our camera was set up for correct exposure based on the flash's on-body compensation dial. Settings for all of the manual flash shots were as follows:

For the P-TTL test shots, the camera was set to Program Auto mode at ISO 100. In both cases, the lens used was a Pentax 50mm f/1.4. Distance to the subject, our still life used for image quality testing, was a relatively close 1.5 meters. The room was illuminated with mild, indirect incandescent lighting at a temperature of roughly 3700 Kelvin in order to simulate shooting in normal indoor lighting situations. White balance was left on the flash preset for all shots, in part to demonstrate the ineffectiveness of camera presets in handling mixed-light white balance.


THE CONTENDERS

Jerry and I put together a group of light modifiers for this test from our combined photographic equipment collections. The list of modifiers represented here is in no way exhaustive – while several of the more common light modifiers are represented in our test group, this is simply a function of what we had on hand. Most of all, we wanted to see how much the effectiveness varied among modifiers of very different designs.

STO-FEN Omni-Bounce

The granddaddy of light modifiers, every photographer with an external flash probably has one (or five) of these in his or her bag. Designed to provide diffusion with a bounce-head flash when there's nothing to bounce against, especially, some photographers never remove these from their flash units.

STO-FEN

With a street price around $20 at most camera shops, the Omni-Bounce is also possibly the most expensive tiny plastic box you've ever bought.

 

LumiQuest FX

LumiQuest's FX (and similar Softbox) is a larger, folding take on a similar concept, designed to soften and diffuse flash light with little loss.

LumiQuest FX

The FX also allows the use of colored gels for lighting effects with a camera-mounted flash.

 

Gary Fong Lightsphere

The original hard plastic Lightsphere, no longer in production, provides diffusion whether used with direct or bounced flash that is supposed to mirror the look of softboxed studio lights.

Lightsphere

Incidentally, its snap-on dome design also does a decent Tupperware impersonation. Cover the hole where the flash goes with plastic wrap and the Lightsphere doubles as a great place to pack a lunch. It also makes you look like the most ridiculous photographer in the room, but if it works, we'll take it regardless.

LumiQuest Pocket Bouncer

No, in spite of the name it's not a portable personal security system. Instead, the Pocket Bouncer uses your flash head fired straight up at an angled bright-white card to bounce the light forward.

LumiQuest Pocket Bouncer

It's a lot like the old index card taped to the top of your flash head, only much more frightening to look at.

 

Professor Kobre's Lightscoop

The Lightscoop is the one modifier in our group designed for use not with an external flash, but with the camera's built-in unit. As the name implies, light from the flash is "scooped" up by the 45-degree mirror and bounced off of the ceiling, meaning that the Lightscoop, like flash bouncing in general, really only works at its best in spaces with a reasonably low ceiling.

Lightscoop

It's by far the most unobtrusive of the modifiers tested, though its illumination ability is tied completely to a comparatively weak pop-off flash. Note also that for testing purposes, flash compensation was boosted to +1EV for the Lightscoop.


THE RESULTS

As noted, two shots are shown for each test (save the Lightscoop): one with manual settings using the Vivitar 283 flash, and one with the camera in Program mode with the P-TTL Pentax flash.

Unmodified Flash (direct)

Test 1
Manual (view large image)
Test 1
P-TTL (view large image)

Exposure is good in both cases, with the manual flash exhibiting the typical "flash photo" look. While there are a few hot spots in reflective materials, the P-TTL unit is able to draw in enough ambient light to soften the effects of the flash while still providing adequate illumination for shooting at 1/60.

Unmodified Flash (bounced)

Test 2
Manual (view large image)
Test 2
P-TTL (view large image)

Not surprisingly, tones are more even across the board in both cases here, with the hot spots disappearing from our P-TTL shot. Both shots exhibit some of the typical dark "down shadows" indicative of bounced flash, but the exposure, even from the manual unit, is very usable and un-flashlike.

Omni-Bounce (bounced)

Test 3
Manual (view large image)
Test 3
P-TTL (view large image)

As the manual shot indicates, the Omni-Bounce's frosted plastic does more than we anticipated to diffuse light output. The results are similar to a standard bounced shot, but with more even transitions from highlights to shadows. In some ways, this shot is the best of both worlds, with the filled-in look of direct flash without the harshness.

LumiQuest FX (direct)

Test 4
Manual (view large image)
Test 4
P-TTL (view large image)

Light from the FX looks direct, but in general, hot spots are well-controlled. The overall exposure on the P-TTL shot, however, is a little "flatter" than some others in this group.

Gary Fong Lightsphere (bounced)

Test 5
Manual (view large image)
Test 5
P-TTL (view large image)

The Lightsphere is bested only by the Pocket Bouncer in the amount of light it directs to the subject, providing many of the same benefits of the Omni-Bounce with even more illumination.

LumiQuest Pocket Bouncer

Test 6
Manual (view large image)
Test 6
P-TTL (view large image)

With 1/2EV of negative flash compensation, the Pocket Bouncer has the potential to be the best tool of the group, but under default P-TTL settings it tends to shift too many of the values in the scene toward the highlight end of the spectrum. Still, while shots don't exactly look "bounced," illumination is almost too strong.

Professor Kobre's Lightscoop

Test 7
Direct built-in flash (view large image)
Test 7
With Lightscoop (view large image)

The biggest surprise of the group, in our minds, is just how much this unit did to provide a natural, uniform exposure when compared to direct pop-up flash. Though it requires (per manufacturer's instructions) a flash power boost to light things up sufficiently, results are really quite good when price is factored in, as there's no need to buy an external flash unit.


THE ANALYSIS

In comparing the test shots, a few things jump out. First, with P-TTL using maximum available light in calculating exposure values, there's surprisingly little difference among any of the P-TTL shots. Bouncing tends to provide a little more even fill and fewer hot spots against reflective surfaces, but even this is subtle in P-TTL. In spite of this, the manual shots suggest that there is more actual light modification going on than the P-TTL shots would indicate, and the less ambient light available, the more variation the P-TTL tests would likely show.

Second, white balance is an issue for most cameras under mixed lighting. Shooting in RAW in order to correct WB issues in post-processing, or taking a custom white balance reading if shooting JPEGs, becomes increasingly important as less flash power is used (i.e. in the P-TTL shots).

In terms of comparative analysis, to our eyes the Lightsphere seemed to provide the most even exposure by a slight margin in both setups, followed closely by the Omni-Bounce and, interestingly, the Lightscoop. Given the limited improvement gained with the physically enormous and visually intrusive Lightsphere, the Omni-Bounce seems like a sensible choice, probably justifying its popularity.

Conversely, under moderate ambient lighting, our test suggests that for P-TTL users especially, the difference between modified and unmodified light often borders on insignificant. Again, as the manual tests show there's more going on here than meets the eye in P-TTL shooting, which suggests that exercising more manual control over your flash and camera settings is the route to take if you're interested in tailoring the look and feel of your flash shots.

Finally, it should also be noted that a huge number of variables, including the angle of the shot, distance to subject, ambient lighting, subject color and luminance, and so on all come into play, and our results are not meant to suggest generalized performance under the complete range of possible conditions. What we can say with some certainty is that while there may not be much performance difference under normal shooting conditions between various diffusers, the benefits of diffused light in reducing hot spots and evening out exposure are clear.

As is often the case, then, the best advice for those looking to jump into light modifiers is not to do as we have done and buy several options. Rather, pick the diffuser that works, in terms of size and configuration, with the way you work and the equipment you have and stick with it long enough to learn its subtleties.