
I find this to be somewhat disingenuous. Based on sensor size, you should be comparing the Panasonic lens to a 133-400mm APS-C lens. The closest lens I could find is the Canon EF 100-400mm f4.5-5.6

This lens is well over twice as heavy, and almost twice as big. And, this lens is also up to a half stop slower then the Panasonic. While I agree that the lens size makes it far less portable then other lenses, it is still, comparatively speaking, very portable.
