Dang it, Ok here it is .. if you really want macro then you should go with a more wide angle than that.. I have a 1.4 24-135 hmm wow that covers a large range .. I use that lens more than I should .. no matter what focal length I'm at it's never soft around the sides .. forget the 50 .. does it have a depth of field preview ? if so it may be worth it ..
Not sure you really understand what macro is. From this post, it seems evident you don't. Wide angle lenses are less desirable for macro work because the short focal length means you have to get right on top of the subject (optical formulas dictate that at 1:1 your lens' front nodal point is only 2x the focal length from the subject). Longer lenses mean you can work further back from your subject, thus minimizing disurbance.
And you might want to re-check the specs on your lens. I don't believe anyone, anywhere, makes a 24-135 that's an f/1.4 aperture. I don't think there are even any constant-aperture f/4s with that range.


