"Amazing Growing Person"

[Gulliver]

Optics and Distances

Again-it is a function of the perpendicular distance from the film plane. Just pointing the camera halfway between 2 people of identical height will not yield equal-height images unless they are exactly the same perpendicular distance from the film plane!
edited to add--they can be different distances from the center of the lens, as long as they are exactly the same perpendicular distance from the film plane.

I have to disagree. From my understanding of optics, we're looking at similar triangles formed by the rays from the head (and feet) and their image on the film. The triangle touch at the center of the lens. What we have to keep constant is the distance from the center of the lens to subjects' heads and camera-side feet. Please see the drawing.

 

[rwguinn]

Re: Optics and Distances

I have to disagree. From my understanding of optics, we're looking at similar triangles formed by the rays from the head (and feet) and their image on the film. The triangle touch at the center of the lens. What we have to keep constant is the distance from the center of the lens to subjects' heads and camera-side feet. Please see the drawing.

Now look at it from the top of the camera, as opposed to the side:
(i don't know how to put a picture in)
Put two objects the same distance from the lens, radially. Put one of them directly on a centerline projected perpendicular to the film plane, and the other offset, but still in the field of view.
the offset object's "ray"s still converge in the lens focal center, but now, because they are offset, have to travel to the other side of the film.
The object on center's "rays" also converge at the lens focal point, but have only to go to the film-plane center.
Trigonometry says that the ones traveling fartherest will diverge more, and make a larger image on the film.
Sound better?

 

[Gulliver]

Re: Re: Optics and Distances

Now look at it from the top of the camera, as opposed to the side:
(i don't know how to put a picture in)
Put two objects the same distance from the lens, radially. Put one of them directly on a centerline projected perpendicular to the film plane, and the other offset, but still in the field of view.
the offset object's "ray"s still converge in the lens focal center, but now, because they are offset, have to travel to the other side of the film.
The object on center's "rays" also converge at the lens focal point, but have only to go to the film-plane center.
Trigonometry says that the ones traveling fartherest will diverge more, and make a larger image on the film.
Sound better?

To help you explain your point, I attempted to render the drawing that you wanted. Please tell us how trigonometry says that the green guy's image will be larger than the yellow guy's image.

I'm looking forward to learning more.

Thanks,
Gulliver

 

[rwguinn]

hang loose Gulliver--I have to get to a place I can actually do this without distractions like work. Will get with you this PM. I think we are mired in semantics, here....

 

[Timothy]

You must be careful in what simplifications and assumptions you make in your analysis.

For instance, you've drawn your lens diagrams and ray traces as straight lines through a simple lens ... one *might* be able to make that approximation, depending on the accuracy and precision of what you're trying to show.

Simple lenses will have curvature of field when imaging objects in a plane. Commercial camera lenses must be designed to flatten the field. Simple trigonometry and similar triangles will not work to explain this if an extremely high degree of precision is required. Don't fool yourself with making approximations that aren't valid.

To comprehensively determine the image mapping, one needs to know about the lens. I can grab any number of lenses off the shelf that will make the images different heights depending on where they are in the field (it's called distortion ... change in magnification versus field angle).

I hadn't gotten involved in this conversation before because I thought the whole premise of this proposed challenge was mind-bogglingly stupid.

[Credentials: BS, MS in Optics. I design and build optical systems that go into orbit and to other planets.]

- Timothy

 

[BPSCG]

[Credentials: BS, MS in Optics. I design and build optical systems that go into orbit and to other planets.]

Yeah, but do your optical systems work where the laws of physics have been turned to hash by dimension-bending vortices? Hah? Answer that, smart guy! And what about Planet X?

 

[Gayle]

Applicant scampers

This was posted on CSICOP on-line on May 20. Perhaps it had something to do with the applicant's attempt to turn the application over to others. Ray Hyman, who usually leads the Skeptics' Toolbox workshop, would be the logical choice to conduct the preliminary tests. That's enough to scare anyone off.

http://www.csicop.org/list/listarchive/msg00483.html

Classics of Skeptical Investigation
August 11-14, 2005
University of Oregon at Eugene

The Skeptics' Toolbox 2005 will focus on the classics of skeptical investigation.

A classic skeptical investigation uncovers the true explanation for a seemingly anomalous event or phenomenon. It also provides insights into how people get to believe false claims. Classic investigations are successful.

We will also look at unsuccessful investigations.

We will contrast the successful to the unsuccessful investigations. In this way, we will seek the factors that discriminate good from bad skeptical inquiry.

Topics to Be Covered Include:

The Girl With The X-Ray Eyes (see http://www.csicop.org/specialarticles/)
Davey's Seances
Memory In Water
The House of Mystery at the Oregon Vortex
The Soal-Goldney Experiments
Clever Hans
Ancient Classics

The workshop will also include the opportunity to work with teams on assigned cases.

(bold added)

 

[Gulliver]

Precision in this protocol

You must be careful in what simplifications and assumptions you make in your analysis.

For instance, you've drawn your lens diagrams and ray traces as straight lines through a simple lens ... one *might* be able to make that approximation, depending on the accuracy and precision of what you're trying to show.

First, Let me say that I respect your opinion, your degrees, and knowledge. I hope to learn from you here.

Second, let me explain a little about my background. My B. A. is in physics. I taught high physics (senior year) optics this spring. My Master's and Ph. D. are in Operations.

Third, let me respond to your comment. Sorry, I'm not going to buy that. We're talking about measuring the distance with a tape measure to a person who can sway or slouch. We won't have distance to within 5%, so let's not try to measure sizes within .01%. There's no high precision anywhere else in this protocol. Let's not measure with a micrometer and cut with an axe. If you can point me to a reference that states that common commercially available cameras, using a common lens (not wide-angle, or fish-eye) distort image size to a detectable margin based on the objects position in the field of view, I'd be grateful.
Regards,
Gulliver

 

[69dodge]

Originally posted by rwguinn
Again-it is a function of the perpendicular distance from the film plane. Just pointing the camera halfway between 2 people of identical height will not yield equal-height images unless they are exactly the same perpendicular distance from the film plane!
edited to add--they can be different distances from the center of the lens, as long as they are exactly the same perpendicular distance from the film plane.

Yes, I agree. I was just describing a special case. If two people are the same distance from the camera, then "they're the same perpendicular distance from the film plane" is equivalent to "the camera is pointing halfway between them."

 

[Gulliver]

Good Job! Re: Applicant scampers

This was posted on CSICOP on-line on May 20. Perhaps it had something to do with the applicant's attempt to turn the application over to others. Ray Hyman, who usually leads the Skeptics' Toolbox workshop, would be the logical choice to conduct the preliminary tests. That's enough to scare anyone off.

http://www.csicop.org/list/listarchive/msg00483.html

Gayle,
You certainly impress me with your research and insights. Please keep up the wonderful work!
Gratefully,
Gulliver

 

[69dodge]

Re: Re: Re: Optics and Distances

Originally posted by Gulliver
Please tell us how trigonometry says that the green guy's image will be larger than the yellow guy's image.

The images will be the same size. But the green guy is farther from the camera than the yellow guy is. The two guys are the same distance to the film plane, however.

 

[Gulliver]

Re: Re: Re: Re: Optics and Distances

The images will be the same size. But the green guy is farther from the camera than the yellow guy is. The two guys are the same distance to the film plane, however.

Yes, I starting to see the point. I'll keep thinking about it. Thanks!

 

[Timothy]

Re: Precision in this protocol

Third, let me respond to your comment. Sorry, I'm not going to buy that. We're talking about measuring the distance with a tape measure to a person who can sway or slouch. We won't have distance to within 5%, so let's not try to measure sizes within .01%.

I wasn't specifically addressing the Challenge Application, because as I said before I thought it was too silly for words.

I was reminding readers that:

"You must be careful in what simplifications and assumptions you make in your analysis."

"...one *might* be able to make that approximation, depending on the accuracy and precision of what you're trying to show."

"Simple trigonometry and similar triangles will not work to explain this if an extremely high degree of precision is required."

There's no high precision anywhere else in this protocol. Let's not measure with a micrometer and cut with an axe. If you can point me to a reference that states that common commercially available cameras, using a common lens (not wide-angle, or fish-eye) distort image size to a detectable margin based on the objects position in the field of view, I'd be grateful.
Regards,
Gulliver

Again, speaking generally about optics and not about the Challenge Application, a wide-angle lens is specifically what I *was* thinking about. I was warning against making an assumption based on simple principles and extrapolating it to all cases. (And in the diagrams showing the simple lens and stick figures, you will have field curvature and distortion.)

- Timothy

 

[KRAMER]

Nasty Nasty

This ex-applicant, like so many others, has turned nasty.

I will post no further emails from him, as I see no point in detailing the nastiness. We learn nothing from it.

We will consider the matter closed, unless we receive an application from the owners of the Oregon Vortex.

 

[jmercer]

Yeah... I particularly like the way he put a world of meaning into the word "Ok" as you used it. I never knew you had so much talent with words...

 

[Bandersnatch]

Prediction:
He will start claiming KRAMER forced him off the challenge, because he was 'afraid' of the vortex. No mention will be made that the applicant themselves didn't apply.

 

[EHocking]

Re: Re: Re: Re: Re: Optics and Distances

Yes, I starting to see the point. I'll keep thinking about it. Thanks!

Hopefully, my attempt at this may help? (If I can get the image to post)

As you can see, the blue and green figures are the same height, and when on the same plane as that of the camera's film plane and if these two planes remain at the same distance from the lens, the resulting images will also be the same size as each other.

But, as you can see, if you move the green figure around the radius from the lens, ray tracing the top of the head and the "right" foot back to the film plane show's the size of the image as resolved on the plane.

This is because the object's plane (that is parallel to the film's plane) is physically closer to the film plane, yet is still the same distance if measured (radially) from the lens.

 

[webfusion]

OK, Nick

Those two words offered by KRAMER to Nick's 5-19 eMail, were just in direct reply to his closing statement (the last sentence of a rather typical convoluted message):

"I'll get back to you when I hear from the owners."


OK, Nick.


Now, let's see if the owners of this silly attraction are prepared to get involved directly with a group of serious JREF people who are totally aware of the optical effect and are 100% positive that no actual growing or shrinking takes place there.

 

[edjunior]

Re: OK, Nick

Those two words offered by KRAMER to Nick's 5-19 eMail, were just in direct reply to his closing statement (the last sentence of a rather typical convoluted message):

"I'll get back to you when I hear from the owners."


OK, Nick.


Now, let's see if the owners of this silly attraction are prepared to get involved directly with a group of serious JREF people who are totally aware of the optical effect and are 100% positive that no actual growing or shrinking takes place there.

I highly doubt they would get involved, it would only be bad publicity for them IMO.
Check out this link if you have not come across it yet. mystery explained