The Panasonic 7-14 f4 will give you a 35mm equivalent range of 14-28 with stills, 13-26 with video, on the GH2, so you can actually get a bit wider than you currently get with the D7000/Tokina combo. It's a really high quality lens, but costs accordingly, almost $900 right now. For quite a bit cheaper, you can go with the Olympus 9-18 f4-5.6. It's 18-36 for stills/16.75-33.5 for video on the GH2 in 35mm equivalency. It's still a very good lens, is super light and compact, and is closer to $550 new, several hundred dollars cheaper than the Panasonic option. I actually went for this lens instead of the 7-14, and while the 7-14 is no question a better lens, I'm really happy with what I get from the 9-18. You can, of course, use your Tokina, but you won't have AF (I don't know if that matters to you).