amehta wrote:
You're right, there was more I should have said: the Nikon TC will not work with that lens, because the TC has a portion which protrudes out past the lens mount, and the 18-200mm sticks out past the lens mount as well.
I believe there are third-party TCs which would "work".
I'm always touting the Kinko Pro 300 1.4 teleconverter. It retains virtually all the quality and sharpness of the lens it's attached to and will cost you only one f-stop. I know this doesn't double your lens focal length, but it will get you closer to your subject with less pain. It is designed in a way that it does not interfere with the rear lens elements of any lens as opposed to the Nikon converter which can only be used with certain lenses.