Poser uses key-frames, so to animate the camera movement would be very simple. Start at frame 1, position the camera where you want the zoom to start. Then go to the last frame and position your camera at the end of the zoom (the more frames you include, the "slower" the zoom will be). By default, all cameras are animated, so your camera will move and zoom when you make your movie. Yes, you will have to render every single frame, and you'll want to adjust the settings to get the desired outcome. By default, Poser will render movies using "display settings" and not "render settings" so your transmaps and such will not show correctly.