I am waiting on this lense next week coming from CR kennedy and want to know when I connect this lense with either a Tamron TC or Kenko TC will I get for example in the tamron case 300X1.4=420mm then the crop factor(Of my Pentax K20d,10D), or just 450mm straight out crop factor,also where can I get a good price on Hoya filters local wise


cheers