it's the same technique i use for those magic eyes

A question: how many people here can/can't do the Magic Eye thing?

No matter how hard I've tried, I just can't make it work. I suspect that it's because my eyes are different focal lengths -- I'm (only slightly) short-sighted in my right eye, but my left-eye is normal.

The different focal lengths may not be directly relevant but, because of it, I've always tended to favour one eye over the other -- I rarely use (focus) both of them at once -- which is one reason why I'm so bad at ball games -- I lose track of the moving object when it "crosses" from one eye (at distance) to the other (close-up).