Un test pour alimenter ton moulin :

Canon EF-S 18-200mm f/3.5-5.6 IS Lens Review
The focal length labels above correspond to those marked on the lens (the 135mm-labeled shot was actually 140mm according to the EXIF data). As the focal lengths make large increases relative to the prior setting (2x from 24 to 50mm), the angle of view rapidly narrows - bringing the subject in closer. The relative increase declines at the longer focal lengths - and the rate of change slows. The lens does not physically extend as fast above 135mm and the net change in angle of view from 170 to 200mm is very small.

Too small of a change? Well, my Canon EF 200mm f/2.8 L II USM Lens frames a 47.25" x 31.5" (1200 x 800mm) test target at 424.88" (10792mm) while the Canon EF-S 18-200mm f/3.5-5.6 IS Lens frames the same target at 369.88" (9395mm) at the 200mm setting (both lenses mounted on a 50D). The Canon EF 200mm f/2.0 L IS USM Lens frames the same target at 425.12" (10798mm) with a 50D. The 18-200 is 87% as far away when framing this subject size - making its 200mm seem more like 174mm at its longest setting at this moderate distance. Regardless, the EF-S 18-200's focal length range is really nice.