I've been told in the past it was a trick. After watching a video review of this model, I took one. So far, so good. It seems really difficult. I've been playing with this on a 18-55mm kit lens on a Nikon d3k series camera. From 18mm to 30mm I get a very cool fisheye effect. For real estate agents who say it doesn't work, that's exactly what it's supposed to do. Try increasing the focal length a bit until the corners come back and you still have a wider field of view than without this attachment.
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