As usual, the 200mm f1.8L did not disappoint, but sadly, it's now broken, and may never be working again. The 70-200mm f4L IS is fantastic. I actually like it more than the 70-200mm f2.8L IS version. It's a lot sharper wide open and the IS is very effective. Due to the dim lights in the woods, I shot most pictures either wide open or 1/2 a stop down. If you don't need f2.8 for the popular zoom range of 70-200mm, I would suggest the f4L IS. Well worth the money, and much lighter and easier on your body (and wallet).
More interesting is the comparison of the Wollensak 209mm f4.5 and the Canon 70-200mm f4L IS at 200mm. The Wollensak was shot on the NEX-5N and you can see the very significant colour and rendering differences between the two lenses. The NEX-5N and the Wollensak has a lot less saturation and contrast, where the Canon is the opposite. I can't remember, but the lighting might be slightly different as the sun was doing hide and seek. Aside from the colours, the bokeh is night and day too. This shows how, despite the similar focal length, pictures can be vastly different between lenses; each has its own characters. Which one you like is a personal preference. For black & white photography, I think the Wollensak will be excellent.
Young Tree - NEX-5N & Wollensak Raptar 209mm f4.5 Copy Lens. Click for larger.
Young Tree - Canon 1D Mark III & EF 70-200mm f4L IS @ 200mm f4. Click for larger
Bokeh - NEX-5N & Wollensak Raptar 209mm f4.5 Copy Lens. Click for larger.
Bokeh - Canon 1D Mark III & EF 70-200mm f4L IS @ 200mm f4. Click for larger
Fallen Leaf - Canon 1D Mark III & EF 70-200mm f4L IS @ 200mm f4. Click for larger
Reflection - Canon 1D Mark III & EF 70-200mm f4L IS.