Intro: The 180mm Tamron is made from a black polycarbonate with a rubberized focusing ring and a metal mount. Though it is made out of plastic, I does not have a cheap feel to it. It is light enough to carry around all day on a neck strap. Some argue that the plastic lenses don't stand up to heavy use but I disagree. I don't belong to the category of people that abuse or are heavy handed with their equipment. Optics and cameras are precision electrical instruments and should be handled as such. The lens is quite large with a large, wide focusing ring. It comes with a pouch and a lens hood. The lens is also equipped with what Tamron calls FEC (filter effect control). This lets you rotate a filter with the lens hood attached. The tripod collar is easy to take on and off and is sturdy enough for all  use. The lens is a 72mm front element. The lens does not "grow" as you focus.

Performance: Focusing is adequately quick on the D200, and accurate. It is noisy though, one of the drawbacks on this lens. However, since this is a macro lens, it is important that the feel of manual focus is perfect. Almost the entire range of manual focus is in the macro range. It is very smooth and precise. The auto-focus is good enough to be used at all magnifications, which is not very common with macro lenses. There is no focus limiting switch as on the Tamron 90mm macro; it is something that would be appreciated on this lens.

Sharpness is absolutely amazing at all apertures corner to corner. There is no chromatic aberration present and purple fringing is non-existent. The sharpness is absolutely mind-blowing. Other reviews that I have read had stated that this is THE sharpest lens they have ever tested and I would tend to agree with them.

Even though the front lens element is fairly exposed, I have yet to see any flare, even when shooting directly into the sun. The lens hood does increase contrast slightly when used, not to mention it is good protection for the front element.

Bokeh is very pleasant. Generally the more blades in the diaphragm the more smooth the out-of-focus elements are. However, even though this lens only has 7 blades, the OOF elements are super creamy and smooth. Definitely one of the best that I have seen.

Summary: Overall this lens performs exceptionally well for its designed use. Sharpness, contrast and Bokeh are excellent and auto-focus is good enough to be used in the 1:1 reproduction range. Manual focus feels excellent and is very smooth. The tripod ring works well and is quite useful. This lens performs so well that I can't imagine using anything else, even the Nikon 200mm macro.

Cheers