Note that you can't do this in regular Glest (I think, haven't used Glest in forever and don't care to ever go back to it). In
GAE, you can choose Photomode from the options menu, which removes all camera constraints. Alternatively, you can allow yourself to zoom out at any time (photomode or not) by changing the lines
RenderDistanceMax=64.00 and
CameraMaxDistance=64.00 to a larger numbers, such as 256 or 1024 (note that a larger render distance will mean that you may experience lag when you rotate the camera to the side, because you have to render a looong distance. Naturally, since there's more rendered when you zoom out, the further you zoom out, the lower your frame rate will be (more apparent on larger maps).
You can download GAE here:
http://sourceforge.net/projects/glestae
