curiosity

@Jon: Over my Fuji 9500 or over the Sigma 55-200 on Olympus E 510 I put a combination of lenses. A front lens from a broken Nikon and one of three X1, X2 or/and X4 Hoya macro. But the "base" is the lens from broken Nikon.
Thank you!

@Jon: Yes, is my "invention". When I shot only with Hoya macro lens I have a blue fringe. When I shot with lens from Nikon I have a green fringe. When I shot with both lenses (with X1 from Hoya) they compensate one another and the colour fringe is visible only when you look at the image at 100%. When I use X2 or X4 the colour fringe is more visible but if I shot RAW ACR can perfect compensate... The distance between lens and subject when I shot macro in this combination is between 3-8 cm, depending on the focal lenght used. And I don't know anything about Canon systems, sorry...