Cheers guys! Many thanks for taking the time to reply.
I should have made it clearer in the original post that sharpness is all I'm concerned about, and whether or not I can do better on that score. The Canon is extremely good though.
I do also have the Canon 100mm f2.8 macro, but it's too long for most situations.
Michael Alan, yes I also own a Hasselblad 39MP multi-shot and, yes, it is astonishing. But, it has to be shot tethered and I am frequently in situations where this is not possible and/or the Canon file size is more than enough - hence my question.
Am I right in thinking that the Zeiss options would be usable with manual focus only? Do they need an adaptor to attach to the Canon?
Thanks again.
D.