Improvement yes, substantial no.
There are multiple small improvements, but it is not a leap.
- the unit is lighter, which helps with handheld imaging.
- lower power setting is good for z-stacking with open f-stop. Had to use ND filters on MT24. I also used it as a trigger flash for a UV modified Metz 45 CT1 with optical slave, and there the negligible light contribution from the MT26 @1/512 power is an advantage as well. Now upgraded to a Buff Whitelight 1600 UV and that is radio-controlled.
- The Canon diffusors clip onto the unit, so do not fall off, and are a bit smaller, so less chance of touching specimen.
- Diffusion strength is a tad better, but not by a large factor. If you use the unit for close-up (1:5 to 1:1), then you may still want to Frankenstein the diffusors, or do something else, like fill light, reflectors, indirect lighting, etc. For close-up I prefer using either studio flash with small softbox, or use my 580 on a Flashzebra cord through a Westcott diffusor and reflector on other side.
- I shoot mainly 1:1 to 5:1, and there the reflectors are effectively a "large light source"; see Hunter & Fukua "Light: Science and Magic". For that the stock diffusors are more than adequate.
The MR14 is a ring light. Never liked those as they produce very flat light. Got one back in the OM days as a feebee, but only used it one day for playing, then went on the shelf. The adjustment options on the MT24/26 will take some time to understand: Rotational angle of reflectors, inclination angle of reflectors, overall power and flash exposure compensation, left-right power distribution. For instance, directing flash not directly onto subject, but only hitting it with a peripheral glance, produces much softer light, and helps with foreground/background illumination balance.
Diffusion is important, but the other factors are equal if not overall more important. Take your time playing around with the unit once it arrives. Put camera on tripod, fix everything onto one object, then start taking lots of pictures (2-300) with all sorts of adjustments of nothing but the flash.
Re your question of improvement, the MT26 will be a substantial improvement over the MR14.
Hope that helps.
as they say, a picture is worth a thousand words.
