P3D Matched Zoom Lenses

[markaren@xxxxxxxxx (Karen Obusek)]

Is there a reason why two zoom lenses made by the same mfgr. ( 70-210)
would be less likely to match at either end VS a pair of fixed lenses by
the same mfgr? Is this not how the X4 lenses are matched? Why Dr T, do
you feel that two 70-210 Pentax lenses won't match up at either 70mm or
210 mm but the Cosina lenses match up perfectly at each end? Is this not
the same thing? I was not intending to use focal lengths in between,
only at the extremes.
Mark Dottle