(Roughly) Daily

“Reality is merely an illusion, albeit a very persistent one”*…


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The Dynamic Ebbinghaus takes a classic, static size illusion and transforms it into a dynamic, moving display. A central circle, which stays the same size, appears to change size when it is surrounded by a set of circles that grow and shrink over time. Interestingly, this effect is relatively weak when looking directly at a stationary central circle. But if you look away from the central circle or move your eyes, or if the entire stimulus move across the screen, then the illusory effect is surprisingly strong – at least twice as large as the classic, static Ebbinghaus illusion.

Each year the visual illusion research community gathers in Naples, Florida for a meeting that culminates in a contest that names the Best Illusion of the Year.  This year’s grand prize winner is captured in the video above.

See all of the finalists here, read more about the contest (e.g., below) here— and check out the cool trophies here.

This is an anamorphic illusion. It begins as a normal photograph and then is tilted backwards and forwards to create opposite vanishing points. The tilting distorts the shape of the head and facial features to create the illusion of an actual age progression and regression. For the age progression the top half of the head narrows, and the bottom half expands creating a more mature look. For the age regression, the opposite happens. The head and ears enlarge and the lower face narrows giving them a smaller nose, chin and neck, which results in a realistic childlike appearance.

* Albert Einstein


As we uncross our eyes, we might recall that it was on this date in 1758 that John Dollond filed for a patent (which he ultimately received) on achromatic lenses, and reported this to the Royal Society.   Isaac Newton had described the blurring effect due to chromatic aberration (the fact that different colored light wave have different focal lengths), which was important in the preparation of lenses for telescopes and microscopes; but could not solve the problem in simple lenses.  Indeed, the answer lay in compounding two lens.  In the event, Dollond had not invented the answer, but had learned it from another lens maker, George Bass, who prepared the first achromatic lens at the instruction of Chester Moore Hall, who actually deserves credit for the creation.

Chromatic aberration of a single lens causes different wavelengths of light to have differing focal lengths.

An achromatic doublet, like the one patented by Dollond, brings red and blue light to the same focus, and is the earliest example of an achromatic lens.



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