Basically the code I had before from you on an old thread didn't rescale the coords or the images when you changed viewport sizeI think it *was* scaling, the view was just being clipped, hence the disappearing act. ;o}
So you're basically doing the same as I did with the code above, except for moving the viewport about too?
I can't see how the problems highlighted above even apply to orthographic mode in the first place? Moving stuff on the Z axis wouldn't make any difference so how else would you zoom in?