As it turns out, I have two copies of the Vivitar 28mm f2, made by different manufacturers. The Nikon Mount was made by Komine (one of my favourite manufacturers) and the other was made by Kiron. Unfortunately, the Kiron version has a Konica mount, which I can not use on the 5D, so I really can't compare the two. I could, however, try them on the G1, but then we will be using only a small portion of the optics, and you will never know how the edges will look like.
Starting with the Vivitar 28mm f2, I am going to provide more details when reviewing a lens, and this will span over multiple posts. For starters, I will include test shots for all apertures with 100% crop. For sure this will take up a lot of my time and shooting walls as test pictures is as exciting as watching paint dry. But, I think the used lens market is huge and lots of people are looking for information on old lenses. I am hoping by providing more details on old lenses, this will help protential buyers decide if the lens is for them or not.