Originally posted by HawaiianOnline Yeah, I already know about the limited AF range of the TC itself. I've already been using one with a Sigma 300mm f2.8 so I'm kind of used to "getting it close" manually, then letting the AFTC handle the final locking up. I find that this works pretty well for surfing and most of the birding I've been doing in Hawaii. I'm just wondering if I could expand things to other brands of glass by converting the mount on the TC rather than the camera body... One of the members on the Pentax forum at dpreview (brandrx) has a setup where he "sort of" mounts a Nikon 400mm f2.8 to a Pentax 1.7x AFTC and uses a jig setup to ensure that the two stay locked together. The PK+MM would help eliminate the jig, and the AFTC would allow "limited" autofocus, correct?
This has often crossed my mind as well. But the cost of the TC might be a little prohibitive to hack up. There are, however infinity adjusted Nikon,canon and Minolta to pentax converters, and each of these is really a TC, so if you did use a much better optical solution it would likely work, with the pentax converter. The biggest issue is you would have manual stop down for the aperture,
The Nikon thing is not really an adaptor, the Nikon mount is close enough to partially engage. The rigging is external to ensure the cameras does not fall off