I use the MPE65 and MT24 a lot [I burnt out one flash tube]. No filter here, although on every other lens I use, I have a protection filter (except for the F-Distagon 16 mm). I do use the MPE 65 hood, both as protection, and to cut down on stray light to increase micro contrast.
On the MT24 I use the garry fong puffers. Drilled a couple of holes and a slit leading to each on each side, and run a rubber band through the holes, so I can move them easily as necessary. The biggest problem is that the rubber bands deteriorate rather quickly, so have to replace them every 6 months. Have to try the stofens.
For >2:1, which I shoot quite frequently, the flash heads are illuminating the background, but not the subject. I use two Wimberley plamps with flash mounts screwed and epoxy glued to one of the ball joints. I looket at the RRS rig. Love RRS for all sorts of things, but the macro flash rigs are too much, IMHO. The Plamps work perfectly fine. The plamps can either be attached to tripod legs, or the foot of the MPE65. The flash heads are then placed right adjacent to the front of the lens.
This becomes even more important with z-stacking. You have to ensure that the light source remains static. If you mount the flash on the lens, it moves and changes illumination angle and shadows. With z-stacking, constant illumination is critical, so you rather use it in manual mode than ETTL. At f/2.8 with >3:1x, even at smallest power setting (either 1/64 or 1/128, don't remember), placing the flash heads right over the subject can emit too much light. Then you have to move the heads away a bit, but the low power setting will still ensure short exposure time (completely agree with Dalantech's tutorial).
I also often do bounce flash, so turn the flash heads away from the subject, and bounce it off white cardboard, or a white porcelain cereal bowl. That is particularly helpful with plant portraits, where you have many crisscrossing elements, or deeply nestled flowers.
Different lighting can get different information. More directional light will give you more local detail (surface sculpture), which can get obliterated with fully diffused lighting. Lighting needs to be matched to what you want to show. There certainly is plain old bad lighting, but there are multiple equally valid good lighting options.
I agree with Dalantech, that the best flash lighting should NOT look like flashed.
I published an article on macro flower photography, which explains and illustrates the above. If anybody is interested, PM me and I will send you the link.
