This just popped up on the local Craigslist:
Pentax-A* 600mm f/5.6 ED(IF) lens for Pentax 645 (manual or digital)

I wish I had the money (and muscle )

[littledrawe]

The handle on this lens would be so nice to have. I have been thinking about a way to get something similar on my A* 600mm for the k mount.

[stormtech]

The handle on this lens would be so nice to have. I have been thinking about a way to get something similar on my A* 600mm for the k mount.

Heck, I'd settle for a nice tripod mount like that which is actually be centered under the weight of the lens........

[Digitalis]

very nice lens, can be tricky to focus manually - like the pentax SMC-67 800mm f/6.7 ED [IF] you really need a good tripod to get the most out if it.

[atlnq9]

Being that I use both the 645 A* 600mm 5.6 and 67 M* 400mm and 1.4x converter. The 645 A* easily wins the ergonomics competition. The image quality of the 67 M* is immaculate without convert and equivalent with converter to the 645 A*. But I was able to aquire a drop in polarizer for the 67 M* which preserves contrast in mid morning and afternoon light much better.

[garyk]

I would love to try a lens like that. But working at that focal length with MF? Wow. Does anyone know where there are some pics with this lens?

[littledrawe]

angus is using this lens, you can look for some of the other photos he has posted

https://www.pentaxforums.com/gallery/photo-pentax-645-600-5-6-plus-2-0-tc-35250/

[atlnq9]

But working at that focal length with MF? Wow. Does anyone know where there are some pics with this lens?

Yeah, my computer... Keep an eye in the medium format forum, I am planning a post with pictures and comparison of the 67M* 400mm + 1.4x and 645A* 600mm with 100% crops, etc. Here is a low res quick edit though shot with 645D and A* 600mm 5.6...

It can be very frustrating at times but I am getting a lot better. Has to be slow moving subjects though or you have no choice of nailing focus...

[angus]

Yup, use it quite a lot, mainly for birds at a middle distance. I don't really find the lack of AF such a problem as an AF that tries to catch every twig in sight can be much worse than keeping the set distance and following a bird through the branches. The depth of field is very limited therefore one has to stop down or wait untillthe subject stands in a way that the whole of the body is in focus. A heavy beast though but also works quite well with the dedicated TCs which I managed to pick up. Will post pictures with TC in my gallery. At 3k$ I still believe it to be a good catch.
Angus