Over the last couple of decades, I've inadvertently become somewhat of an authority on Vivitar & Kiron glass. Please feel free to contact me about any Viv or Kiron lenses, and I'll give you the scoop on any of them. The Viv S-1, 135mm f/2.3 that you are asking about, is a very good one. Not great, but very good. And Komine produced some of the best Viv S-1 lenses ever made. I think that you'll be quite satisfied with it's results.