Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: Piece of crap

I usually don't like to write poor reviews. But this really requires it. I was OK with the idea that the focusing was poor in low light. However, I can never use autofocus with this extender. It simply won't work. And while I was expecting some degradation in quality of the image, practically all pictures using this are unusable. I would not recommend it.