</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (David Hall @ Mar 5 2003, 02:08 PM)</td></tr><tr><td id='QUOTE'> But I have an ancillary question: not all sheet films, as an example, have bases of uniform thickness, or so it seems. Bergger, for instance, feels siginificantly thinner than HP5, when you hold a single sheet. I wonder if this is a question of hardener in the base, or of thickness. And if it&#39;s of thickness, I wonder if that would affect depth of field at very wide apertures or very wide angles?

dgh </td></tr></table><span class='postcolor'>
I am almost sure it is thickness, but not enough of a difference to make difference in DOF or Sharpness.