6 Macros - G7 plus ...
Thanks for the compliment.
Close-up filters are single lenses, just like other filters (eg. polarizing, UV, etc.). They usually come in sets of three: +1, +2, and +4 diopter, although they can be also be bought singly and with other levels of diopter strength (see the lensmate site - raynox makes some interesting close-up filters).
A close-up filter works just like a spectacles for somebody who is farsighted. The filter enables the camera to focus on objects that are closer to it than would otherwise be possible. The higher the strength of the diopter (eg. +4 versus +2), the closer you can get to your subject and still be able to focus on it.
I use the close-up filters along with the zoom on the G7 to allow me to zoom in on a subject in macro mode without having to back so far away from it that it becomes too small a part of the captured scene. That little insect in the fourth picture in my original post would not have been visible in the picture if I had not used a diopter lens to allow me to get close to the little guy.
I hope that answers your question.