Just a quick and dirty tests i conducted on my DIY Diffusers for my MT24EX.
Edit: my latest diffuser: concave diffuser - cheapest, easiest to DIY yet the best so far - can be found here.
Old i.e Rev 1 diffusers look like this:
More info on gen 1 diffusers construction here
New i.e. Rev 2 diffusers look like this:
I used a pair of Sto-fen inside to simply the DIY process. The housing (where the stofen is in) was made from some clear PP material on a mineral water bottle. Not easy to make it stay in that elliptical form. You can try using moldable plastic to form the housing though.
Moldable plastic. Just heat and form it into any shape you want. Can be reheated and re-shaped over and over again!
Light efficiency tests:
Old (Rev 1) vs New (Rev 2) DIY Diffusers: seems like Rev 1 needed between 1/8th and 1/16th flash power to match the same exposure on Rev 2 at 1/32th flash power. Rev 2 should be 1.5 stop more efficient than Rev 1. All images converted from RAW with default settings.
Rev 2 seems to have slightly bigger apparent light size too.
All tests done at 1:1 because that is the worse case scenario, for the MPE65, at least.
I have only tested this gen 2 DIY Diffusers in the field once. More field tests required. Anyway, here are a few shots using Gen 2 Diffusers.
All shot with Canon MPE65 1X-5X macro lens and MT24EX Twin Flash
Canon MPE 65mm f/2.8 1-5X Macro Lens for Canon SLR Cameras
Canon MT24EX Macro Twin Lite Flash for Canon Digital SLR Cameras
A common misconception among most macro photographers is that twin flash is always better than a single flash/light source. I beg to differ. If anything, the twin catch lights from the MT-24EX really irritates me. Read more about it here. I had to rely on post processing to tone down the bright twin catch lights in certain macro subjects' (esp jumping spiders) eyes. With the invention of the concave diffuser, the twin catch lights is no longer a problem.
Please also check out how you can use just a single flash/speedlight i.e. the 270EX (or equivalence, e.g. the Nikon SB400) with adapted concave diffuser concept to cater for the longer working distance of longer macro lenses other than the MPE65.
Check out my macro rig here.