"Digital zoom" is cropping, and does not increase magnification or resolution on the subject at all.
What we are talking about here is not "digital zoom" as it is most often understood; Panasonic uses the term extended zoom for what we are talking about here. It is correct that this is an in camera cropping (except at wide-angle, where it is probably a down-res processing). There is another thread http://www.birdforum.net/showthread.php?t=105219 discussing advantages and disadvantages of this approach.
tomo_76 said:I read an Amazon review that said that a ring of black background is added to the image is this true as I intend to take several panoramic shots and edit them together.
I don't have the TCON-17, but based on the converter I used on my previous camera, you will not see the black ring when using a converter while the camera lens is zoomed in. When you start zooming out, then there will be a point at which the converter limits the view of the camera, and you start seeing the black ring. If you want to use wide angle on the camera, then you should take off the TCON, putting it back on if you want to gain a reach beyond what the camera can do on its own.
Niels