>This is really a interesting lens. At 10-15mm, just raising or >lowering the focus point slightly gives a completely different >perspective because of the extreme convex lens design.
The perspective change with shooting angle is not specific to the design of this lens; any lens of similar focal length would do the same. In fact, all lenses do it, but it's more obvious with wider angles because of the closer shooting distance that such a lens allows while still "getting it all in", .
>If you haven't tried a super-wide lens you should, it's very >entertaining and challenging.