[FONT=Verdana, Arial, Helvetica, sans-serif]The New 70-200mm ControversyJan 20 (commentary)--When the new version of the 70-200mm came out, the first round of angry forum posts on the Internet centered around focal length breathing (the tendency of a lens to lose focal length as you focus closer). Shortly after that settled down there started a new round of "physical defect" assertions. Some of these included photos through the front of the lens of what looked like a ring in the lens that had defects in its structure. The premise of most of these posts was that this ring was a functional part of the lens and thus the lens needed repair.[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]That would be incorrect. The "rings" that people claimed to see defects in are actually light baffles: by not having a flat edge just outside the internal element that moves forward and backwards during zooming, less light is reflected into the edges of that element, which increases contrast. Most Nikon zoom lenses have a variant of this baffle design. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Apparently this baffle is a cast part (metal poured into molds), and some of the casting is less than precise or has molds that aren't holding up to repeated use. The ring doesn't have to be perfect, though, as the sole purpose of the "rings" are to not present a flat surface for reflections. I've not commented thus far about this controversy as I thought that Nikon would quickly realize the bad word-of-mouth circulating and issue an official bulletin that explained what people were seeing. Unfortunately, that hasn't really happened--a few Nikon tech centers have responded to individuals with a variant of what I just wrote, but no "official" response has been made--so the controversy still exists.[/FONT]