The 135 Celtic I had, the only Celtic I had mind you, seemed to be a very nice lens. From what I've researched on the Celtic line the optical formula's were identical to the Rokkor's, they just built them a little "cheaper" a-la the Series E line. There's some argument about the coatings being the same, but I believe when Minolta began computer designing they figured the coatings into the total design, so it'd seem an expensive prospect to do a total re-design just to cut a little cost in coating, especially on what was intended to be a "value priced" lens. Who knows, because nobody I've seen so far seems to.
Originally Posted by Christopher Walrath