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[the Earl of Whirl]

I had an interesting visit to Hobby Lobby today.  I spotted an "Illusion Spinner" kit.  It is something like what The Toycrafter had 20 some years ago.  There is a tip that fits in a yellow plastic blank and five different illusion patterns in the package.  It comes from Kidz Labs 4M company and the whole thing was only $2.99. 

[ta0]

That is a good price. Do your recall what were the illusions?

Here is a much more expensive and upscale version of illusion spinners that were also made by The Toycrafter (this is made by Naef Toys), the Op-Tric Tops:



Fechner color illusion is probably the most common name for this illusion in which colors seem to appear on a black and white rotating image, but the top that shows the effect is sometimes call Benham's top (that was the name given by The Toycrafter.)

Scientifics Online has it on sale: http://www.scientificsonline.com/op-tric-tops.html
If you don't mind the price and want to order it, I got an email with an offer for free shipping from them. Enter CLR2ES at checkout.

[ta0]

Found the Illusion Spinner for $2.99:



That is the "look at the back of your hand and see it morph" illusion (or the "get dizzy" illusion)  They also have an "Illusion Science Kit" for $9.99 that includes several different illusion spinners that look very similar to The Toycrafter's.  To those I would add the "missing penny makes it cheaper" optical illusion 

[figs]

These are fun.  I am really fascinated with the Fechner effect.   In fact I painted a Trompo Grande to try and recreate the effect.  But it didn't really work.  I think that a spintop spins too fast for the effect to work,  and falls over before it gets slow enough for the eye to see.

[the Earl of Whirl]

I like the paint job, though!  Sorry it didn't work.

[ta0]

I agree with Mike, the paint looks cool anyway.

I just measured the rotation speed of my Benham's Wheel top from The Toycrafter. With a strong snap it starts spinning at close to 2000 RPM but I don't see colors until it goes under 1000 RPM or more like 800 RPM. The colors stay to about 250 RPMs but below 500 RPMs you can see blinking of the black region going around. The ideal speed is around 600 RPMs or about 10 turns per second.

Normal tops fall over at about 1200 RPMs, so they are too fast. But a 10" top can probably go down to 750 RPMs and it may work. A future paint job, Alan? 

Have you noticed that when to invert the sense of rotation the colors change? I have also found that other people see different colors than the ones I see.

[figs]

Thanks guys!  It's one of my favorite paint jobs and regardless of the effect the top itself is one of my favorite players.  I've done some demos with it before and it always gets a lot of attention.

Ta0 the fascinating thing about the optical effect and the reason that people see different colors is that there is no color there, its just your brain interpreting the effect.  Apparently they do not actually understand why the effect happens.

[ta0]

Figs: you may consider trying the Mach Bands effect. It is not a color illusion, only a brightness illusion, but will work with a fast rotating top. We discussed that before on the old board (see thread here). I obtained a good illusion with a pattern on the top of a top, but it should also work by painting the side:



The rotation of the top creates the necessary gradients, but the illusion itself is from the resulting static pattern so it can be seen in a photograph:



By the way, this pattern is very similar to the 4th one on the Naef Toys set, which is supposedly only about Fechner. It could be that a low speeds gives you one illusion while at high speed it gives you the other.  I think I am going to bite the bullet and buy the set. Even if I can reproduce it, this will look nicer and be a great conversational piece.

[Mark Magyar]

decided to go to Hobby Lobby on my Birthday and I did happen to get one of these  spinners. 5 different designs like that of early Toycrafter whirligigs.
and thank you Larry D. for wishing me a happy birthday. 

[ta0]

Belated happy birthday, Mark!

[the Earl of Whirl]

Yes, happy birthday Mark.  Sorry I missed it.  Glad you got some fun tops for your birthday!

[Mark Magyar]

Oh, thank you for birthday wishes.
I came across the following page awhile back
http://www.fsinet.or.jp/~eohashi/i/iro-e.htm
COLOR CHANGING TOP
(By GINGA KOBO)
Color Changing Optical Illusion Tops
12 different designed tops to look at...