If you want a true macro lens, you want one that has a 1:1 ratio. As far as I know, you're only going to find that ratio in a prime macro lens. But some of the zooms have decent ratios between 1:2.3 to 1:3. If you do a lot of macro photography, then I would say get one with a 1:1 ratio. If you want more versatility, I would look at a lens like the Sigma 17-70mm f/2.8-4.0 DC Macro Zoom Lens which has a 1:2.3 ratio and cost around $449 US at B&H.