Finding longer telephoto lens for 645

[Guest]

Wildlife photography requires longer lens than even
the 350 mm with 1.4X teleconverter.

I have tried using Hasselblad 500 nmm tele-tessar
[circa 1970] with 2X TC. Long enough, but very difficult
to focus sharply and a slow lens: f8.

Has anyone found a better way: e.g. using

Mamiya 500/5.6 lens with Mamiya 2X TC?
Pentax 67 lens: 600 mm or 800 mm
Using another manufacturer's 2X teleconverter on 350mm lens
Combining two Contax 1.4 TC using a modified extension tube?

I am sure each solution is imperfect, but has anyone found anything that works until Contax produces 2X
TC or 500 mm lens

Jerry

 

[Guest]

Why not get a Canon 400/2.8 L IS and an EOS-1V
body? With the new 2X you get 800mm/5.6. Focuses like lightening, the entire unit is O-Ring sealed, plus the IS and d&ened mirror helps make up for the smaller format.

I have the 350/4 and 1.4X and once used the Canon
400mm/2.8. The Canon is better than you may think.