Originally posted by Fenwoodian Not possible.
Yes, it is possible, manual focus. I saw photos taken with a K1 , a Nikon 400 f3.5 + K mount TC, becomes a 560 f5.6. The Nikon 400 f3.5 A-IS ED lens can be purchased for less than 1K on ebay.
BTW, if you can't get sharp images with the DFA150450, humm that's highly likely that you won't with a Nikkor lens. One hint why is that is because you seldom use a 450mm lens at f5.6 because the DoF is so thin (a few inches) that any slight error or focus ruin the sharpness of the image (relative to sensor resolution) because the maximum sharpness is only present at the focus plane and so, sharpness drops on front and at the back of focus plane.
Nikon shooter of 600 f4, stop it down to f8 otherwise too many shots aren't exactly sharps because of the DoF and focus accuracy.