Good Morning, Lee,
I have this lens mounted on a 4 x 4 Calumet board, if that would be of any help to you. I expect that it would be at least a very tight fit on a Tech III, but someone else will have to comment on that. The lens is excellent. It's very sharp (at least between ƒ8 and ƒ32), and, as you indicate, its speed helps on the focusing. Its only drawback is weight and bulk.