I am considering purchasing a 400mm f3.5 to use on film and, in the future, on digital (probably not before two or more generations of digital Nikons). Is this a good optic, wide open? How about with the TC301 converter? Should I be concerned that I will not have the opportunity to evaluate it before I buy it? Assume it is from a seller on eBay with a good rating and long history. Is it possible to make comparatively good wildlife pictures with manual focus and film, when the bar has been upped by AF-S VR lenses and digital cameras with endless buffers?