Agreed on all points. I'll just add that butterflies kind of straddle the transition from close up to macro in the sense that there's such a huge difference in size among the different families. The photos I saw with a long lens were all large Swallowtails with wingspans of several inches. When I'm photographing a Western Pygmy Blue (Brephidium exilis) I can't fill the frame of my 5Dmk2 with my macro lens: the wingspan is less than 1/2". Next time I shoot those I'll want to use extension tubes or better yet that crazy Canon lens that does 5x marco! Add to that a gyro for stability...
Good points on being able to fill a frame with really tiny subjects, even when using a true 1:1! I chose the 7D for the reason that it accentuates my macro shots by its 1.6 conversion factor, but even here there are times where it simply does not ... and, as a matter of fact, I myself have extension tubes for just this purpose. However, like you, I am also seriously considering getting the MP-E 65mm for ultra-close detail, rather than relying on tubes.
Regarding the 200mm Zeiss: Is that for Sony mount or Canon? The Canon are all manual focus for whatever reason and I'm never going to be interested in that. I have a bunch of old Zeiss glass from my contax days adapted for EOS and I rarely use it...eyes not what they used to be.
I do not know if the Zeiss will be in multiple mounts or not (or even if it will ever come to exist for that matter), but I would imagine that it would, seeing as they have now converted the mount to their existing macro lenses to fit the Canon.
I hear you on the manual-versus-autofocus aspect of the lens. However, in my case, I already have the new "L" 100mm macro lens, and while it is a great lens in many respects, in others I find it to be worse than the elder macro. It seems to me that, while there are many situations where the new IS and the new AF can enable a shot to be captured that might not have been possible otherwise, the flipside to this is that Canon's total focus on the "automated" aspect of its lens severely limits those instances where manual focus is
called-for. With my lens, for example, even when I shut-off the AF and the IS, and attempt to focus manually, two things occur simultaneously that I find very troubling: (1) the motors to these automated mechanisms still "try" to work [you can actually hear the strained sounds] and this fact sometimes slightly changes my own handheld focus setting; and (2) the focusing ring itself does way too much with far too little rotation. A 1/4-inch turn with the Canon focusing ring effects dramatic focus changes, whereas with the elder Zeiss lens it doesn't do as much. I believe the actual numbers state that the you can complete the entire range of focus with the Canon, from close-up to infinity, with a mere 180-degree rotation ... while it takes the Zeiss lens 720-degrees of rotation (or 4x as much rotation) to go from close-up to infinity. The Canon's manual focusing ring, in being so sensitive as to allow automated/mechanized turning, essentially becomes ridiculous for manual focusing. I have repeatedly found that if I turn the Canon focusing ring just a little bit, I often go "passed" the correct focusing point ... and if I turn it just a little bit in the other direction, I go right passed the proper point again, in the other direction. It almost seems like the new Canon lens forces
a person to use AF all the time
. By contrast, because the Zeiss focusing ring must be turned-and-turned-and-turned to achieve the proper focus point, a person is able to really get to the exact focus point with manual rotation. Thus, for extreme precision manual focusing efforts, the Zeiss is simply a better tool for the job.
It is for this reason that I would probably go with the Zeiss, as I already have the new-generation AF/IS from Canon, but for those instances where extreme precision manual
focusing is called-for, I just don't think the Canon AF lenses are the best tools for the job. What they are is the best tools for hand-held AF