Lubbyman wrote:
The obvious replacement for the lens is the DA*300mm f4 with 1.4 teleconverter. Together, they give 420mm at f5.6, which is very close to the long end of the 150-450mm. Without the teleconverter you have 300mm at f4, which is close to the middle of the 150-450mm. Of course, zoom and the short end are lost but presumably it's the middle to long end you want for wildlife. Optically, the DA*300mm is superb and the 1.4 teleconverter is made for it. I can't make a direct comparison with the 150-450mm because I don't have it.

You'd notice a distinct reduction in weight - together, the lens and teleconverter are about half the weight of the 150-450mm. I went down the 300 + 1.4TC route after hearing a talk from a semi-pro wildlife photographer who said that his ideal wildlife kit was a 300 f4 + TC because he was now at an age when carrying heavier kit around held no attraction. I knew what he meant!

Steve