New From Stephen Ingraham

[Steve]

http://www.birdforum.net/article.php?a=4

[Atomic Chicken]

Greetings!

I particularly enjoyed this part:



You might remember the experiments with chickens. Chickens were fitted with spectacles that inverted and reversed their view of the world. They stumbled around for a few days, but most of them quickly adapted to the new view, and were soon functioning normally (as normally as a chicken can). Evidently the chicken brains “remapped” the visual space for the new conditions. If chickens can get used to an upside down, reversed view of the world, certainly we ought to be able to.


Aside from the "as normally as a chicken can" poke at poulty intelligence, the interesting part about this is that an experiment WAS performed at a major university that proved humans have the same ability. Although I cannot recall what university or the date of the study, I remember the details.

Essentially, special eyeglasses were devised containing prisms that inverted the participant's views of the world. Over time, a similar effect to the chicken experiment was observed. The brain "rewired" the visual interpretation center after about a week and the participants suddenly saw the world normally. Unfortunately, after the experiment was over and the glasses were removed, it required another adjustment period in order to reverse the new "wiring"... the participants now saw the "normal" view of the world as upside down!

Best wishes,
Bawko

[matt green]

Greetings!

I particularly enjoyed this part:





Aside from the "as normally as a chicken can" poke at poulty intelligence, the interesting part about this is that an experiment WAS performed at a major university that proved humans have the same ability. Although I cannot recall what university or the date of the study, I remember the details.

Essentially, special eyeglasses were devised containing prisms that inverted the participant's views of the world. Over time, a similar effect to the chicken experiment was observed. The brain "rewired" the visual interpretation center after about a week and the participants suddenly saw the world normally. Unfortunately, after the experiment was over and the glasses were removed, it required another adjustment period in order to reverse the new "wiring"... the participants now saw the "normal" view of the world as upside down!

Best wishes,
Bawko

hmmmm,it's a crazy crazy world.matt

[Martamm]

Most recent (dielectric) coatings can (even) exceed the efficiency
of the best Abbe-Konig and porro systems.

To me this sounds quite a big promise, but I hope Mr. Ingraham
is correct. The more efficient prisms are of course welcome !


Marko

[elkcub]

He said:

More recent coating systems employ over 70 layers, in multiple applications, to raise the efficiency of Schmidt Pechan systems to equal or exceed that of the best Abbe-Konig and porro systems.

The implication is that these "recent coating systems" are currently in use, either by Zeiss or other manufacturers. One doesn't come away with the feeling that he considers one inverter system inherently "better" than the others, but rather that it all depends on the refinement with which they are implemented.

I'm very glad this article was written. Thanks, Steve!

Elkcub

[kabsetz]

To my sense of semantics, the phrasing "to exceed" that of the best Abbe-König or Porro prism systems at the very least implies that the design, at least in this one respect of light-transmission efficiency, would indeed be superior.

Kimmo

[henry link]

I don't see how a Schmidt-Pechen, even with 100% reflectivity mirror coatings could "exceed" or even quite equal the light transmission efficiency of a Porro or an Abbe-Koenig, since it requires more internal reflections (and has two more glass to air surfaces than a cemented Porro). "Total internal reflection" may indicate that no light actually escapes from the prism at a reflecting face, but surely a small amount of light is scattered at each internal reflection since no glass surface is perfectly flat.

[hinnark]

Excellent written by Stephen making again some difficult matter more understandable. What is new to me is the different way phase coatings works with both types of roof prisms, the Abbe-Koenig and with Schmidt-Pechan prisms and that they prevent against polarization caused by the mirror surface inside the S.-P. prism. But I´m not sure about this: what has phase shift got to do with polarization and when a phase shift increase by internal reflection of a Abbe-Koenig prism why there isn´t one inside porroprisms?

Steve