How are you zooming in and out in ortho? Are you using glTranslate with a value in the z parameter? If you are, this doesn’t work in glOrtho, as it is 2D. What you’ll have to do in Ortho mode is simply use glScale and scale everything to simulate zooming. Does anybody know if I’m wrong about this? But this is what I’ve always done.
The zoom in the ortho works fine, I’m doing it by using “glScalef”, its the switch to perspective that doesn’t work properly. When I switch it zooms in to the object and then the zoom in and out (using “glTranslatef”) is very small (I use the mouse button and actions to zoom).