Macrodiffuser.com sells diffusers for the Canon MT-24EX, MT-26EX-RT, and the Yongnuo YN24EX E TTL macro twin flashes. I recently purchased a set of MT-26EX-RT diffusers and put them through my normal "field studio" (patio table) and post processing. In post I let the Photoshop Elements 17 RAW editor auto adjust the shot. In the main editor I rubbed out any dust spots and used Topaz Labs Denoise 6 to remove image noise, Detail to sharpen (Creative Detail Collection / Overall Detail Light I), and Clarity to adjust micro contrast and saturation (Collections / Macro / Flower I). All of the photos were processed in the same way, and I made no specific adjustments to the specular highlights (I never do).
Although shipped from the UK I was presently surprised at how quickly they showed up at the post office, especially since I have a military postal address (civilian working at a US Navy base) so the package had to go from the UK to the States and then to Italy and it only took about a week. The diffusers are very well made and even though the ABS plastic is thin they feel sturdy. They slip on and off of the flash heads with a little twisting, and will not come off by accident under normal use. There is some assembly required, but it's pretty easy. The goal is to cover the entire inner surface of the diffuser with some reflective stickers (supplied with the diffuser). Ian explains the process really well in this video:
Although the video was made for the MT-24EX the instructions apply to all of the macro twin flashes. There's quite a bit of overlap with the stickers, but that just makes it easy to get all of the inner black plastic shiny. The push pins that hold the front diffuser to the diffuser shell work well, but if you take them on and off a lot eventually they will wear out. I wouldn't expect any problems with the push pins under normal use, and there are two extra ones just in case you need them.
For me the real test of a diffuser is how well it can diffuse light at 1x since the working distance is going to be the greatest. Due to the Apparent Light Principle the larger a diffuser is relative to the subject the better the diffusion, and as the magnification goes up the twin flash heads get closer to the subject. So if a diffuser can perform well at 1x it will just get better at higher magnifications. Here are the tech specs for the gear:
Canon 80D (F11, 1/250, ISO 100) + a Canon MP-E 65mm macro lens + a diffused MT-26EX-RT using Ian's diffusers (both flash heads attached directly to the Canon lens mount), E-TTL metering, -1/3 FEC, second curtain sync). They are all single, uncropped, frames taken hand held. I'm holding on to the plant stem with my left hand, and resting the lens on that same hand to keep the scene steady.
First up is a very small beetle with a very reflective shell -pretty much a torture test for any diffuser.
The specular highlights are very well controlled in that shot. I did notice a slight hot spot in the Elements RAW editor, but nothing to really worry about. The light loss with the diffuser is only 1 1/3 stops compared to shooting with the bare flash heads, so a few additional layers of diffusion could be added inside the diffuser to force the light to spread out more and you could still keep the light loss below 2 stops. For comparison my home made diffuser loses 2 stops, but I'm forcing the light through four layers of diffusion. B&H Photo sells a Pro Gel Pack for about 25 USD counting shipping that will allow you to experiment with several different types and grades of diffusion so you can tweak the light until you get the quality that you want. For MT-24EX users that gel pack is highly recommended since those flash heads have a Fresnel differ that almost looks like a clear piece of plastic. For the record the MT-26EX-RT has a much better built in diffuser.
In addition to the beetles eating my Lavender I also found a caterpillar munching on my Mint. Again shooting at 1x so I can record the specular highlights at their worst.
Pretty much the same results as the beetle shot, the specular highlights are very well controlled. I also picked up a lot of texture detail in the Mint leaf, another indicator that the diffusion is looking good. I also wanted to see how well I could light this critter at 4x to test the diffuser performance at a steep angle between the subject and the flash.
Again no issues, plenty of light on the caterpillars face. You can see where the flash heads were just by looking at the specular highlights. The only problem I ran into was with the size of the diffusers. It's great that they are so wide because that helps with the diffusion at 1x. But I like to shoot with the flash heads at the 12 O'clock (key) and 3 O'clock (fill) position and that's not possible with Ian's diffuser due to the width. I did have the flash heads as close as I could get them but the light still looks pretty even. But don't let my personal preferences bias you against this diffuser, the "out of the box" light quality is pretty darn good.
I got nothing but good things to say about Ian McConnachie's diffuser set. Really good light quality, really well made, and I think that they'd hold up to the abuse that most field macro shooters will put them through. Is the light quality up to par with my home made set? Nope, and I didn't expect it to be because I'm using more diffusion layers. But there aren't many, if any, alternatives out there and if you don't like the diffusion as is you can always pick up that gel pack and experiment until you get the light quality that you want. I'm gonna call Ian's macro twin flash diffusers "highly recommended"!
Footnote: I paid full price for the diffusers, and Ian McConnachie didn't know that I was going to write a review. In addition the links are not affiliate links, so I make no money if you click though to B&H Photo or Macrodiffuser.com. So this post is not sponsored in any way.