What I like about the 1.7x AF on the long lenses is that the AF focus range becomes constrained, seems to make AF a lot more fast and precise.
It really just provides the final snap to the focus, which I have to say I need these days. I only wish the AF 1.7x worked with all of the AF sensors, and not just the middle one.
- MCC -----
Mark Cassino Photography
Kalamazoo, MI
http://www.markcassino.com
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