First a cut and paste of an earlier post:
Just received my copy of the MT-26EX-RT. The flash heads look to be the same size as the MT-24EX, but the flash tube and the reflector look bigger -I'll check later when I get home. The controller is really small! In the past I looked for a compact flash to take with me when I don't want to carry a lot of gear, but now I don't think I'll need to. The MT-26EX's controller looks like it's about half the volume of the one on the MT-24. Now to build a diffuser for it. The Cannon supplied diffuser (looks like a Sto-Fen on steroids) are included inside the pouch that the flash comes in and there are storage pockets for them as well as the lens flash mount. One word of caution concerning the storage pouch: It closes with a small piece of Velcro, and the carrying handle is at the top on the other end of the opening. So be sure to secure the Velcro or you'll dump the flash onto the floor. The construction quality of the MT-26 seems very high, but not so much the pouch.
The included diffuser is very solid, and the clips that attach it to the flash heads are really large -seems really solid. The diffuser is very opaque, and the plastic is pretty thick (easily a full millimeter). More of a hard plastic, unlike the old Sto-Fens for the MT-24. Gonna be easy to build a diffuser that attaches to it, and attach it to the flash heads with just the clips. For all of the photos included with this post the MT-24 is on the left and the MT-26 is on the right.
Here's a shot of the controller. The MT-26 is a little bit thicker, but not by much.
Here's a shot of the flash heads. Very little difference in size with the MT-26's being marginally larger:
Last is a shot of the front of the flash heads. The area of the flash is a little larger on the MT-26:
The light from the MT-26 is still going to be brutally harsh out of the box, even with the included diffusers. I took a life size shot of a toy car with the Canon 35mm macro, working distance about two inches (5 CM), and the specular highlights were almost completely blown out even at -1 FEC and there was a sharp transition between the specular and non specular areas of the image (poor diffusion). Also I had to upgrade the firmware in my 80D to 1.02 before I could control the MT-26's settings from the camera's menu. Once I did I could set everything on the flash, including the custom functions. Overall very happy with the size, weight, and balance compared to the MT-24. I just need to work up a diffuser set for it.
Edit #1: Knew I'd forget something: The LED focusing lamps on the MT-26's flash heads are going to be a game changer for some users -they're VERY BRIGHT!