Quote Originally Posted by Marco Buonocore View Post
Perhaps the more mathematically sound members can determine weather this approximate 2mm difference will be apparent visually when making a print, stopped down to a working aperture.
Not sure about that. However, when it is properly in focus, a 2mm difference in paper height will not be noticeable.

In his book, Edge of Darkness, Barry Thornton did an experiment. He put his easel on a 1/2" thick piece of board then focussed normally and made a print. He then made a print without the 1/2" board and another print with two boards. He says that he could see no difference in the sharpness of the prints 1/2" either side of optimal focus - and he was a sharpness fanatic!

So basically, a 2mm difference will not be discernable - however, you do need to be focussed first, and this is where you are having problems.