Diffuser comparisons for 100mm macro lens

I really wish I could just buy three Canon Speedlite 580EX II flash units, mount one directly on the camera, run the other two wirelessly on each side as slaves, put a nice big soft box diffuser on each of them, and be done with it! I’m beginning to think that’s the only way I’m going to get the kind of full flash insect macro photographs that I want with larger subjects that require the use of my 100mm macro lens. You know what I mean—nice, even, diffuse, vibrant light that comes at the subject from multiple directions (eliminating those annoying specular highlights in the eyes that result from more unidirectional lighting) and with enough power to allow minimal flash pulse durations (resulting in maximum motion freeze). But I can’t—the money is not in the budget, and even if it was I’d have to think seriously about the logistics of carrying and setting up in the field three Speedlites every time I wanted to photograph an (often moving) insect.

Thus, I continue trying to come up with some kind of system that makes the most of my Canon MT-24EX twin flash unit. It’s not that I don’t like this flash unit—I love it because of its light weight (good for field use) and the front-of-the-lens mounting feature that, with its dual heads, gets the flash heads closer to the subject but avoids the “flat” lighting effect of typical ring flash units. In addition, for those shooting insect macro photographs with Canon’s shorter focal length MP-E65 macro lens, the twin flash unit is probably the best choice of all, since the lens is right on top of the subject and it is relatively easy to place diffusing materials between the subject and the flash heads—Alex (Myrmecos) with his tracing paper diffuser and Kurt (Up Close with Nature) with his concave foam diffuser are two of the more successful designs out there. I use my MP-E65 lens a lot, but I use my 100mm macro lens a lot more because many of the beetles I photograph are best photographed at magnification ranges between 0.5–1.0X and, thus, are a little too large for the 65mm lens. The longer lens-to-subject distance of the 100mm lens may be helpful for working with skittish subjects, but it also creates challenges for the MT-24EX because of its relatively low power (more light drop off) and small flash heads (more specular highlighting). For the past couple of years I’ve been using a large sheet of polypropylene foam jury-rigged to the front of the lens, and while it too has functioned fairly well, I keep thinking that if I can just get the flash heads closer to the subject—each fitted with a good diffuser—then it should be possible to achieve results similar to what can be done with the 65 mm lens.

The photos below show the results of some of the ideas I’ve been working on. My main idea was to use extenders that would allow adjustable placement of the flash heads relatively close to the subject and diffuse the light from them with a modified version of the Sto-Fens+Puffers that I have tried in the past. Here is an example of the system mounted on my camera using cheap, flexible arms mounted on a plate attached to the bottom of the camera. If I decide to use this system in the field I would want to purchase much sturdier extenders (e.g. Really Right Stuff), but at only $25 these flexible arms are perfect for proof-of-concept testing. For the modified Sto-Fens+Puffers, I completed the modifications shown by Dalantech (No Cropping Zone) (I was planning to do this when I first tried the Sto-Fens+Puffers but soon found that I preferred the concave and tent designs by Kurt and Alex, at least for use with the 65mm lens). At any rate, to test the ideas I selected a very large (for long subject-to-lens distance), very shiny (for maximum specular highlighting potential) beetle from my collection (Megaloxantha bicolor palawanica, a stunning jewel beetle from Palawan, Philippines) and set it up for “face shots” that simulate my favorite pose for beetles in the field. Keep in mind that this was not intended to be a test of lighting for pinned specimens in the studio—that is not my interest, and there are much better approaches for doing that—but rather a proxy for the kind of lighting and diffusion I might achieve in the field. Here are the results:


#1 – flash heads mounted on lens, diffused by modified Sto-Fens+Puffers

The example above show the results obtained when using the modified Sto-Fens+Puffers with the flash heads mounted directly to the front of the lens. I didn’t try this shot without diffusers, but I doubt it would be much worse than this—specular highlighting is bad because of the small apparent light size, and overall the lighting is not very even with dark shadows and harsh highlights. This shot is a perfect example of the problems inherent in using the twin-flash with a long macro lens.


#2 – flash heads mounted on flexible arms, diffused by modified Sto-Fens+Puffers

This second shot shows the results when the modified Sto-Fens+Puffers are mounted on the flexible arm extenders and positioned as close to the subject as possible to maximize apparent light size. This was supposed to be the system that gave me the results I was looking for, but honestly I am not impressed. The highlights in the eyes are certainly larger than in the previous photo, and the overall lighting is not quite as uneven, but still the highlights are harsh and fairly sharply defined. Considering the greater difficulty in positioning the flash heads compared to lens-mounted, I have to consider the marginal improvement in lighting not worth the effort.


#3 – flash heads mounted on lens, diffused with modified Sto-Fens+ Puffers and concave diffuser (closed)

This third shot has the modified Sto-Fens+Puffers once again mounted on the lens, but also attached is my trusty concave diffuser. Honestly this combination of diffusers provides much better overall lighting and softening of the highlights compared to the previous shot, even though the flash heads are mounted on the lens rather than positioned close to the subject. Apparently the concave diffuser, though further away from the subject, still has larger apparent size and thus allows light to be transmitted to the subject from a larger apparent area. I have not normally used another diffuser between the flash heads and the concave diffuser, but my impression from this shot is that the modified Sto-Fens+Puffers do a good job of dispersing light before it hits the concave diffuser to soften the “hot spots” behind it and provide somewhat more even lighting across its surface.


#4 – flash heads mounted on lens, diffused with modified Sto-Fens+ Puffers and concave diffuser (open)

When I use the concave diffuser, I normally pull the corners back and attach them to the tops of the flash heads with Velcro to minimize light blow back (although how effective it is I really don’t know). Just for kicks, I decided to try some shots with the concave diffuser not pulled back, but left open and extending out over the subject. I did this because that actually more closely approximates how smaller versions of concave diffusers are used with the 65mm lens. The effect was not only remarkable diffusion of light, with specular highlights and hot spots almost completely lacking, but also much better lighting behind rather than just on the front of the specimen. That said, the quality of the light lacks vibrancy and seems somewhat “dead,” perhaps because of the great distance between the flash heads and the diffuser and the MT-24EX units relatively limited power. The large diffuser extending far out in front of the lens might cause problems with bumping and skittish subjects, but I am intrigued enough by this result to continue with some field testing to see what I think.


#5 – flash heads mounted on flexible arms, diffused by SoftBoxes

The final shot shows the results of another promising setup—this one again uses the flash heads mounted on flexible arm extenders to get them close to the subject, but instead of the modified Sto-Fens+Puffers I fitted each flash head with a mini SoftBox. This was not easy, as the SoftBox is designed for much larger flash heads than those of the MT-24EX, so I took another set of Sto-Fen diffusers, cut off the face, then hot-glued the SoftBox to the open Sto-Fen. Thus modified it was a simple matter to “snap” the SoftBoxes in place over the flash heads. Despite the term ‘mini’ these Soft Boxes still provide a much larger area for light transmission than the modified Sto-Fens+Puffers, and this much larger apparent light size has a dramatic effect on the overall lighting and diffusion. I’m tempted to say I like this one best. However, I do have to consider ease of function in the field—the lens-mounted Sto-Fen+Puffers and concave diffuser, either open or closed, would certainly be easier and involve no further cost (for better extenders than the cheap flexible arms I now have), but if SoftBoxes on flash heads placed close to the subject gives better results than I may have to go with it.

Will you please help me decide? I setup this little poll so you can tell me which of the systems you thought gave the most pleasing result in terms of vibrant, evenly diffused light. I can’t (to my knowledge) tell who’s voting (and if there is a way don’t tell me because I don’t want to know), so don’t let privacy concerns prevent you from adding your vote—the more voters that participate, the better information I get to help me with my decision.

Copyright © Ted C. MacRae 2013

24 thoughts on “Diffuser comparisons for 100mm macro lens

  1. Cool ideas Ted (I’d love to see photos of the rigs for each set up to see how obtrusive/spooky the solutions may be). I voted for 5, but I also really like 4 for different reasons. The colours are certainly flatter in 4 (I’m assuming the angle of reflection off the beetle is the reason), but I think the hairs and punctation are more visible, which can come in handy depending on the subject. Either way, I think you’ve got 2 winning solutions in your toolkit now, and I’m looking forward to seeing them in action this summer!

    • You can see photos of the Sto-Fens+Puffers and the DIY concave diffuser (both closed and open) in the links provided.

      So far #4 and #5 running neck-in-neck – glad to see my indecision validated.

  2. No. 5 is my favorite and most clearly shows details between the eyes. No. 4 is the least effective, in my opinion, and definitely looks “dead.”. Hey, what’s with that broken left antenna, anyway?

  3. I have been using on flash on Camera, with a Lastolite 8×8 ezybox hot shoe soft box. It’s largish a bit unwieldy in bushes but it is good inside and out. After of lot of testing the double baffling and use of the regular diffuser that comes with the Nikon flashes I get amazing soft wrap around light. That is light diffused three times. I am looking for for something to fit in the shoe on my camera to give me a bit more tilt, buts not a big issue. The lastolite is about $80 in Canada and very portable. Of course inside on a stand the light is great too.

  4. I’ve got 3 Speedlites and run the rig you wish you had the money to buy… I wish I had the money to buy an MT24-EX! Not in my budget either. Maybe you should plan to visit AZ and we can trade flashes for a few days. 🙂 My rig is just huge, bulky and heavy. I still haven’t got the diffusers figured out (anything I like) but that will make is huger and bulkier! Is the grass greener on the other side of the fence?

    • Beware the MT24-EX. When it works it’s a good system, but I’ve bought a couple of lemons and have had to send them in for repair when one of the heads stopped working. Canon does not always repair these effectively. Speedlites are bulkier, but they are also more reliable and have more power.

      • Fortunately I’ve not had any problems with my MT-24EX, except the bracket problem that you are aware of. The replacement bracket you gave me has also become non-functional, so I sent them both to Canon for repair. Long term I’m saving my money for a Really Right Stuff bracket w/ extenders so I can just avoid the lens-mount bracket altogether.

    • Paul – what kind of bracket system do you have to hold all that stuff!

      At first, it was really important to me to have something light and portable for the field. Now I’m of a mind that I would rather suffer the weight penalty if it means I can finally get the kind of shots that I want. It’s all about priorities.

      • I have a set of arms made by Stroboframe that are discontinued. The camera connects in the middle and there are arms made from steel rod on either side. The end of each arm has a flash cold-shoe on it. They are pretty adjustable as to length and angle. I put the 580 on the camera and control the other two (smaller) Canon flashes with it. I haven’t got a diffuser that I like. Maybe we can figure that out when you come to AZ!

    • I didn’t even think about keeping the MT-24EX and running a third flash as a slave. I could probably find a fairly inexpensive used 430EX – it might even fit on the same bracket with the extenders for the twin flash heads. Great idea, thanks!

  5. No. 4 is in my opinion the best. This is simply because there a likely to be no blown highlights. This makes it much easier to sharpen the image or adjust it in post processing. Yes, out of camera other diffusion can look okay with its contrastier image, and the blown highlights produce a type of natural, but crude sharpening. However this is a baked in look, and there is very little you can do with it. When I orignally designed the concave diffuser principle, it was meant so I could apply far more sharpening to above life-size images, which had been softened by diffraction. Specular blown highlights makes it much harder to sharpen, as it just ends up looking over-sharpened.

    Also whilst No. 4 may looks flatter and less bright than the others, a levels adust could alter this in seconds. This is what I’ve never been able to understand with these criticisms of the light being too flat etc. As long as the light is directional, increasing the contrast on No.4 would make it look much more like the others. The differences in appearance are misleading. You can clip highlights and white with PP, but you can’t unclip blown highlights with PP.

      • Sure I will be back. The longer distance diffusion problem is something I’m still working on. I’ve had a few different ideas. I just need to sort a few other things out to be able to devout the time to finish off what I was attempting. I realised when I started to look into it that there was a lot of mistaken preconceptions about flash photography in the macro distance. For instance I see no purpose for a convex diffuser for macro photography. Convex diffusers are designed to throw light around a room. Most field macro subjects aren’t in an area where you can bounce light from the surroundings. I’ve also found convex surface diffusers are far brighter in the centre than the edges. My end of lens curved diffuser acts like a room where light can be bounced off nearby surfaces. Unless an insect is in a flower or something similar there are no nearby surfaces to bounce light off.

        I’ll write about what I’ve discovered in more detail. However, the basis of everything was defining the problem. We’re essentially attempting to dim a specular reflection from a convex shiny surface, the peak of which is an actual reflection of the flash. This is why a convex face for a diffuser is wrong. It means the brightest central part of the diffuser is closest to the peaks of the shiny concave surfaces of inverts. Exactly the opposite of what you really want. Ideally you want the lighting for a shiny convex surface to be strongest from the side, and weakest head on. A concave or curved surfaced diffuser has this effect. It reduces the difference in the intensity of light reflected from the apex of convex shiny surfaces, relative to the sides. This is the essential problem I have been trying to address. To ensure the light being reflected from subject, which comes from the more oblique angles, is closer in intensity to the light being reflected from directly in front of the subject. In other words the aim of the diffuser is to increase the intensity of light towards its edges, whilst reducing the light intensity at the centre. At close range a lot of this is simply done by distance i.e. making the edges of the diffuser closer, and the centre further away. Hence the advantage of a concave or curved surface relative to the subject.

        This isn’t the only way this works. However, it is the best explanation I can give on how I defined the problem and what I was attempting to do.

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