I didn't expect to become National Geographic quality in 2 months, but my macro really sucks. I must to be overlooking or misunderstanding some salient principles in order to be so awful. I'm using a handheld T1i with 550ex a manual Tamron 90mm f2.5 with 2X tc and a Pringles diffuser that is properly aimed and only has a thin layer of packing foam that you can almost see through. I should be getting plenty of light, but sometimes I'm not, and oddly, it seems to be when there is more ambient light. But that's only one of my problems. Unfortunately I'm on stone age internet and can't post examples or shots of my setup. The other day I took a single shot of a bee with my SX130 and and no flash-I think it is better than any of the hundreds of shots I've taken with this macro setup. That was very depressing and discouraging, but I'm not giving up.
I think part of the problem is holding this lens still enough to get crisp shots, and/or being able to assess focus when it's stopped down a bit. But at 1/200 or less, I'm not sure that should be so big of a problem. I've experimented with all the different flash settings and nothing seems to make a difference. I'll admit I'm still a bit confused about how to get flash working properly for me, I don't seem to get what I expect from a super short effective shutter speed. I certainly don't get how people are using their flash at 1/8 power, because even in bright light I can't do that. Occasionally I get a pretty decent shot but it seems to be pure luck and I can't replicate my successes. I'm hesitant to blame it all on the lens as there is likely considerable operator error involved. But I'm not sure how to eliminate it.