Ultravid magnification anomaly

[BarneyW]

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If I look at a distant rectangular shape through may Leica Ultravids, e.g. a 3x2 paving stone, looking at it end on, the far end of it looks larger than the near end. I thought this was a fault in the lenses, but a friend with other high quality binoculars finds the same thing with his. 

Can anyone throw any light on this?

[jaapv]

The distortion is deliberate. If the image were completely rectilinear and you were panning following a moving object the spinning effect would make you dizzy. This distortion will mitigate the effect.