Bob,
Thank you for your (as usual) thorough explanation. Upon reading it, I realize I used to know most of that. I have extension tubes... sitting on my desk. I'd just forgotten what they're for. Old Timers'? Well...I'm going to keep on going and avoid that conclusion as long as I can.
What is it that you are wanting to do?
I have some footage of bees that are about 3/8 of an inch long on sunflowers that are about 4 inches wide. Looking at the footage, you'd guess the bees and flowers are full size. The amount of detail that can be seen in these tiny bees is so clear, you'd never guess they are so small. I'd like to do more of that - and other beasties that happily eat my garden. This footage was taken from about 11 - 12 feet away with my 100-400 lens - 2x on the micro four thirds, so from 200 - 800, 35mm scale. I'd like to get even more detail. I have a 100mm Canon macro lens. It is not an L lens and I've never been stunned or thrilled with anything I've done with it the way I often am with the 100-400 L. I've been trying to figure out how to get the best out of both of them.
With extension tubes and tele converters maybe I can get down to the thousands of tiny eyes detail in a fly's eye. Or a dragon fly's eye. You know... some Sidd and ants stuff!
Transparent abdomens! I find macro shots fascinating and would like to do macro video, if I can.
I've looked at a lot of "macro" still shots and usually come away thinking, 'I can already get flower pollen as well as that.', but then there are some shots that are so magnified you'd almost have to guess what you're looking at and then when you figure it out it is amazing. I often realize I have bugs in my flower shots after I'm back in the house looking at the footage. I want to concentrate on specifically hunting for them. They're much more interesting than - oh - another - pretty - flower - so - what.
From what I've been reading lately, micro 4/3 is particularly good for macro. Perhaps there are some old lenses out there that would be better, and cheaper than my Canon 100mm macro. Zeiss or Leica? As brands go, would those two be likely to be sharpest? If so, I need to figure out what kind of bodies they were originally designed to fit so I can see if they can be adapted to the Pany GH4 for a reasonable amount.
[Edit: add:
Is an "achromat" a close-up lens?]
thanks again,
Patrice