The one touch version (push pull) is a very good lens IF you can find a good one. It was made by Kiron and had a Matched Multiplier available (a dedicated 2x converter). I had a Canon FD mount one in the 1980s and sold it, much to my regret. I tried to get a good example recently and ended up buying 3 with no luck. Glass is clear, but sticky aperture made them a non starter, (at least without a CLA). I ended up getting a Tamron 103A 80-210 f3.8 in Mint condition instead, with the bonus of adaptall mounts. That is an awesome lens if you can get one. Usually cheap on ebay.