Review Macro Flash Diffuser Shootout!

AK diffuser vs home-made diffuser

Most of us macro bug shooters rely on electronic flash to illuminate our subjects. Flash units are convenient and deliver tons of light with the right color. It is great that the flash duration is very brief, effectively preventing motion blur in the photos.

A downside to bare flash is that the light is very harsh, giving deep shadows and bright hotspots. Those of us doing hand-held bug photography have for many years solved the harshness issue by using home-made flash diffusers. These setups work by projecting the light from an on-camera flash onto a translucent sheet that is mounted a short distance away. Folks have fashioned many versions of these using matte plastic sheet, diffusion sheet from junked monitors, or packing material. The different setups were cheap, easy to make, and effective.

More recently, several commercial flash diffusers have emerged, with Cognisys and AK being leading brands. Some of these diffusers come in different sizes to accommodate the variety of camera and flash systems used in macro work.

These diffusers basically all work the same, but the commercial offerings look very professional. They work well, but are expensive. Online reviews are quite positive about the performance of the store-bought diffusers. (Reminder: online review sites make money when you click through and buy, so they tend to be positive about the products.)

On the strength of the reviews and the experiences of friends, I bought an AK model. My initial results with it showed that it gave a nice light, but seemed to require quite a bit of power from the flash. After using it for a bit, I wanted to learn more about how it compared to my home-made diffuser. I ran some tests to assess two main qualities: the softness of the light, and the power needed from the flash. The tests were done indoors on a static subject so that the tests could be controlled, and to produce photos that would be easy to compare.

My home-made diffuser comprised a fan-shaped translucent sheet cut from a document portfolio bought at Staples. It was mounted on the end of the lens with an elastic band. A highly-reflective snoot extended from the flash head to the perimeter of the diffuser. And that's it, with some Velcro to give it stability.

In the photos below, note that the AK diffuser is quite a bit taller than the home-made unit, but the home-made one is more inclined towards the subject.


AK diffuser on the left. Home-made diffuser on the right

I did my tests with a Canon EOS R7 camera, RF 100mm F2.8 L Macro lens at ƒ/13, 1/320s, and ISO 100. I used a Canon 580EX flash and repeated the experiments with a Godox TT685 unit. The built-in Wide Angle adapter was in place for both flashes. The flashes gave similar results, so only the Canon flash results are shown here.

I found the lighting quality to be quite similar in all cases, but subtle differences can be seen (see the examples below). Look at the highlights in the face, the shadows under the eyes, and the tone of the area under the chin of the figurine. Power use was also important. The AK demanded more flash power, which extended the recycle time of the flash. At times that can cause missed shots.


Magnification 0.6 X. Images cropped.
AK diffuser on left. Flash power 1/4 Home made diffuser on right. Flash power 1/8 +0.3


Magnification 1.0 X. Images cropped.
AK diffuser on left. Flash power 1/4 +0.3 Home made diffuser on right. Flash power 1/8


Magnification 1.4 X. Images cropped.
AK diffuser on left. Flash power 1/4 +0.3 Home made diffuser on right. Flash power 1/8

My conclusions are as follows:

• There isn't a great difference in light quality in the comparisons.
• In the shots taken at a magnification of 0.6 X, there is a small difference in light quality between the two diffusers, and I prefer the home-made diffuser.
• At magnification 1.0 X, the light quality overall is a bit softer than it was at 0.6. The two diffusers give pretty well the same lighting quality to my eye. I really don't see a significant difference.
• At magnification 1.4 X, the diffusers give almost identical very soft light, with a slight edge going to the AK diffuser.
• The AK required around 1 to 1 1/3 stops more light for the same exposure.

Both diffusers are easy to set up, and they store flat for transport. The AK comes with an LED light that could be useful in dark situations. Unfortunately it doesn't come with a powerpack for the light. It needs to be purchased separately. The home-made version can be fitted with a small LED light if desired.

Based on the test results, I would suggest making your own diffuser unless you don't feel confident in your crafting abilities. In that case, by all means, buy a commercial diffuser.


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[paddler4]

Thanks for posting. Very helpful, and timely for me as I’m about to redo my macro setup.

I assume the 1+ stop difference is because of the reflective inner surface of the snoot. Is that right?

 

[Archibald]

Thanks for posting. Very helpful, and timely for me as I’m about to redo my macro setup.

I assume the 1+ stop difference is because of the reflective inner surface of the snoot. Is that right?

Hi, Paddler. I'm pretty sure the main difference is the density of the diffusion film. The AK device uses a heavy material. It looks like white paper from the outside. Because of its density, it scatters light very well and gives a very soft light. It suppresses hotspots. The downside is that it reduces the brightness, and therefore requires a higher flash power setting for the same exposure.

I have tried several different diffusion sheets over the years. They all appear to be less dense than the AK material. So they should give a less even light.

As with many things in photography, it is a compromise. Heavier diffusers give better light but less of it. It isn't always necessary to have the most even light, though. A bit of modelling can be beneficial at times.

The snoot adds about one stop of brightness in my experience. I think the AK snoot and my home-made snoot behave similarly.

Note the difference in shapes of the diffusion surfaces. The AK is quite tall and has a somewhat greater surface area. However, the upper part of the AK is farther from the subject. Therefore it is contributing less light, due to inverse square light falloff.

 

[paddler4]

Ed,

Thanks very much. Very helpful.

I have experimented with quite a number of diffusion materials for macro work. Years ago I settled on two sheets of baking parchment paper.

I'm about to make the switch to the OM-1 Mark ii for macro, and I intend to give up my effective but very cumbersome DIY macro flash rig when I do. My rig held the flash off camera, pointed toward the bug, with a smaller homemade diffuser taped over the end. Terrible for balance, but the lighting was very good.

 

[Archibald]

@paddler4 - paper is works well. There are lots of reports of folks using vellum paper. Paper is not good in rain.