Pentax 645 Advice Hi all. Today my Pentax 645 arrived in the mail! It is the original version. I have searched for over two years and am elated to finally have it!!! It comes with 75, 45, and 150mm lenses. I am new to automatic cameras because until now, I shoot the all manual Pentax K1000 35mm. For those of you you have and are currently using this camera, I have a few questions: 1.) Of the three lenses, which is best for portraits? 2.) Will there be a huge learning curve moving from my Pentax K1000? 3.) Which mode is best used for the camera; manual, aperture priority, or shutter priority? 4.) What are your experiences with the Pentax 645? Thank you much, Jamusu.