I have a Kiron 70-210mm f/4 Macro Zoomlock/Focuslock lens that I picked up for next to nothing a few years back.
I have taken exactly 2 images with it on my old D1h. All of the pictures I have seen from this lens (online, and my own) looks as if it cannot form a critically sharp image.
All of these images were produced by digital cameras (which all look strangely distorted). Could this be the problem, or is this lens model a dud?
I have, the Kiron manual focus, dont think I've ever seen a Kiron AF lens, It was the second zoom I owned, the first was the Nikon 35 to 70 E, after I retired from news I didn't want to spend the money on a Nikon zoom. Phoenix Camera had the Kiron used, I shot with in it on my F3 and FG, not a bad lens, not great, once stopped to F8 did ok, some distortion at 80 and 200 better in the middle. Contrast was good, just little soft compared to my Nikon primes. At the time I was shooting TriX and Kodacolor, don't think I ever shot Tmax 100 so can't say how sharp it would have been.
My first zoom was a Kiron, purchased in about 1981. I can't say for sure but I think it too was a 70-210. Mine was a dud, compared to the images my Pentax prime lenses produced the Kiron was like photographing through the bottom of a beer bottle. Never purchased non-Pentax lenses after that.
I have a couple of older Kiron telezooms. One of them has significant internal haze that would affect the image. The other one seems fine and makes reasonable images as far as I remember. You can check for haze by shining a flashlight through the lens; look from both ends. This will often be sort of scary - even lens that work ok may show a little veiling. But sometimes, it will reveal a lens that is cloudy enough to be retired if not cleanable.
Rhetoric about digital cameras and strange distortion is off topic in this forum AFAIK, that was part of the issue.
Then shoot some film and see what you get, I know there has been a lot of debate about using lens designed for film on a sensor, the coating may impact the final image, rather than speculate just shoot a roll of film. Other wise post on the 100% digital portion of the site, you might get a more informed response.