Beam rings or optical illusion?

[Chaz]

Some time ago there were some threads commenting on the rings in certain led flashlight beams. The manufacturer claimed that these rings were optical illusions. The general consensus seemed to be to reject this claim. Then I came across the following:
http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html
Would this have any bearing on that claim? What do you think?

 

[Jarl]

It doesn't matter if they're actually there or not as far as I care. The point is, I can see them, and they make the beam ugly. Therefore, optical illusion or not, they are a problem.

 

[HKJ]

http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html
Would this have any bearing on that claim? What do you think?

No, that picture is using contrast and shadows to fool the eye, a flashlight beam on a white wall is not supposed to have either.

 

[gadgetnerd]

Basically it's a problem with Cree LEDs, as most manufacturers seem unable or unwilling to design reflectors which can project a beam with smooth transition from hotspot to corona. Instead we get raccoon eyes beams. Even OP reflectors do little to get rid of the rings.

Most torches with Lux I/ III/rebel, SSC and Osram LEDs don't have rings.

My definition of bad is when the beam artifacts distract me when I'm trying to read a book in bed with the torch. None of my Cree torches are fit for this purpose.

 

[Oddjob]

I agree with Jarl and gadgetnerd.

I had a P1D a while back that had dark crescent around the hotspot. As I rotated the light the crescent also rotated.

 

[McGizmo]

No, that picture is using contrast and shadows to fool the eye, a flashlight beam on a white wall is not supposed to have either.

If you have a very bright spot next to a less intense spill area, you will have contrast. However, with the strength of your statement, I am going to have a sit down discussion with some of my flashlights!

I know when I first started messing with the Cree's I saw some artifacts which I suspected were illusion and I confirmed this with a light meter. As said though, what you see is what you see whether it is real or a trick of perception.