I took a walk at the park yesterday evening to give this lens a go and get some fresh autumn air, that is before the chill sets in. As stated earlier, flare is big issue with this lens. So especially shooting around sunset, I suppose I was just setting myself up for challenges. In any case, I tried to use it to my advantage. The critters however, were certainly out in force, particularly the praying mantises. These are all post processed save for the crops. I included 2 100% crops to show sharpness of the lens. One is of a wheat stalk and the other is of one of those fuzzy weeds.
Someone posted some info in a dPreview forum.
Just googling this lens, as you have most likely done if you are looking for more info on this provides a lot of information about this lens however some confusion occurs since Vivitar, later released a newer, different formula in their Series 1 line, the 90mm f/2.5 macro lens. Although it only goes to 1:2 magnification on its own, an accompanying adapter for 1:1 was manufactured and sometimes sold with the lens. It was that version, also known as the "bokina" that has been hailed as one of the best macro lenses to date. Vivitar's 105mm f/2.5 (also Kiron, Dine) is also very notable.
More to come on this post...time to sleep!