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Nikon 18-200mm. (enlarge)
Actual Focal Lengths
Some folks are worried that they got cheated and 200mm isn't really 200mm. I pulled out my 80 - 400 VR and 80 - 200 AFS and compared. At 500 feet (200 meters) the 200 mm setting of my Nikon 18-200mm gave exactly the same field of view as my 80 - 400 VR and 80 - 200 AFS at their 200 mm settings. For the long distance shots for which you need 200 mm you have an honest 200 mm.
Those who are worried misunderstand how internal focusing (IF) works. Internal focusing allows this 200 mm lens to focus down to 1.5 feet at 200 mm, which is closer than any other 200mm lens! Not even Nikon's 200mm macro lens focuses as close as the Nikon 18-200mm.
IF works by twiddling many internal factors to allow focusing without the whole lens having to move in and out. Standard lens design equations tell us that even if you extend a 200 mm lens by an extra 8" (200 mm) to focus more closely that it only focuses as close as 32" (800 mm). Do you really want your 18 - 200 to poke out an extra 8" as you focus, and then only focus to three feet? Of course not. This would be in addition to the extension you get when zooming to 200 mm.
IF works by deliberately shortening the focal length as you focus closer. Shortening the focal length internally has the same effect as moving the lens out to focus. Focal length is 200 mm at infinity where you need it and shortens as you focus closer.
IF lens are supposed to appear to have shorter focal lengths when compared to traditional lenses at close distances. Don't drive yourself crazy comparing since every IF design is a little different. My 24 - 85 AFS IF lens matches this Nikon 18-200mm at close distances, while the Nikon 18-200mm at 6 feet and 200 mm matches my 80 - 200 AFS set to 130 mm.
So what? The Nikon 18-200mm focuses far closer and and gets tighter close ups than any other 200 mm lens, except of course for the $1,000 Nikon 200mm macro. The effective focal length has to shorten as you focus closer for the lens to work. When doing the nerd comparisons above you'll notice that the lenses to which you're comparing the Nikon 18-200mm can't focus anywhere near as close or get as much magnification as the Nikon 18-200mm does, regardless of comparative focal lengths.
The only loss you have with the IF system of the Nikon 18-200mm at 200 mm is if you're shooting at the restricted minimum focus distances of the older lenses, which were eight feet for the 80 - 400 VR and five feet for the 80 - 200 AFS. At these distances you'll match the 200 mm setting of the Nikon 18-200mm at about the the 135 mm - 120 mm settings of the older lenses. So what? Just walk one step closer with the Nikon 18-200mm and you'll get a tighter image than the older lenses which can't focus that close.
Even at 25 feet this is irrelevant. My 18 - 200 mm at 200mm gives the same image as my 80 - 200 AFS does set to 190 mm.
The wife of a photographer couple I know hates having her photo taken. She knows her husband's 70-200 Canon can't focus closer than five feet, so she stays inside that range. If my pal had one of these 18 - 200s he'd be able to get all sorts of embarrassing shots of her making faces at him thinking he can't focus!