I am concerned about focusing my V35. It does pretty good in the normal ranges, i.e. 5-8x, but when I follow the directions to calibrate the focus by raising the head to its uppermost position (16X), and then setting the focus, when I lower it to the 3X position, it falls "ever so slightly" out of focus. If this was ANY OTHER BRAND, I would not worry in the least, but this is Leitz, and I cannot accept this as being within normal Leitz tolerances. If any ideas, please help me out! Thanks.