A revolution in thought

[LadyShea]

Originally Posted by peacegirl

So what forms on the lens? Air?

Nothing "forms" on the lens. That's a phrase you made up yourself and it has no meaning to any one who understands cameras or lenses or focusing.

The lens focuses incoming light into the camera

[LadyShea]

Duplicate

[peacegirl]

Originally Posted by Dragar

This statement is mostly gibberish, but please note the eye has a field of view just like a camera. That's why you can't see what's going on behind your own skull, amongst other things.

The eye has a field of view like a camera, but a camera's lens can focus on an object leaving the surrounding view out of focus. Eyes can't do that.

Originally Posted by Dragar

You'll also note that walking a few steps directly away from a camera does not take it out of the field of view, as the angle isn't changed. So why do you think it will in your 'experiment'? It makes less and less sense.

The angle might not be changed, but the size of the object gets smaller and smaller until it is no longer in view. That's what I mean when I say walking a few steps away from the camera's field of view.

[peacegirl]

Originally Posted by LadyShea

Nothing "forms" on the lens. That's a phrase you made up yourself and it has no meaning to any one who understands cameras or lenses or focusing.

The lens focuses incoming light into the camera

How about light forms on the film. Is that better?

[LadyShea]

Originally Posted by peacegirl

The eye has a field of view like a camera, but a camera's lens can focus on an object leaving the surrounding view out of focus. Eyes can't do that.

Of course they can, and do. You are not focused on everything all at once when you see. What the hell are you talking about?

[peacegirl]

Originally Posted by ceptimus

You don't know what you're talking about with this talk of 'visual range'.

I can't see a fly that is 100 yards away. But if you painted the fly silver and shone a laser at it, then I would be able to see that same fly, especially at night.

Originally Posted by Ceptimus

But even with the laser-lit shiny fly, I wouldn't be able to see it if there were some other bright source of light nearby, dazzling me.

If you're going to throw around technical terms like 'visual range', you need to define what you mean.

That's why I'm trying to define what I mean by "visual range". A visual range is the typical daylight range for a medium sized lens. Regardless of how laser lit a shiny fly is (I can't help but picture that poor fly all lit up ), there is a point at which that fly would be out of the field of view.

[LadyShea]

Originally Posted by peacegirl

How about light forms on the film. Is that better?

You are using "forms" oddly. What do you mean?

[LadyShea]

Originally Posted by peacegirl

there is a point at which that fly would be out of the field of view.

There is a point at which the fly's apparent size is too small to be resolved. See Optics

[peacegirl]

Originally Posted by LadyShea

Of course they can, and do. You are not focused on everything all at once when you see. What the hell are you talking about?

Choose a low numbered aperture (large iris opening) for results with a shallow focus or shallow depth of field. Primarily only the subject that your camera lens is focused on will be in focus.

Focus on Aperture

[peacegirl]

Originally Posted by LadyShea

There is a point at which the fly's apparent size is too small to be resolved (see subtended angles)

I thought light continues on indefinitely. Why shouldn't the image of the fly get closer and closer to the lens as it reflects that light?

[LadyShea]

And the eyes do the same thing. You are only focused on what you are looking at and everything else goes out of focus, until you look directly at it.

[peacegirl]

Originally Posted by LadyShea

You are using "forms" oddly. What do you mean?

Light strikes the film. How's that?

[LadyShea]

Originally Posted by peacegirl

I thought light continues on indefinitely. Why shouldn't the image of the fly get closer and closer to the lens as it reflects that light?

Because of optics! And the way light works (see intensity and the inverse square law)!

[LadyShea]

Originally Posted by peacegirl

Light strikes the film. How's that?

Better. Does it still fit with what you are trying to describe when you say mirror images form on a lens?

[peacegirl]

Originally Posted by Spacemonkey

Peacegirl, efferent vision is still conclusively disproved by the fact that cameras function afferently and yet do not record different images to what is seen with the eyes. Your account of real-time photography, to the extent that you've provided any account at all, directly contradicts the known physics of light. As you could see for yourself if you would just answer my questions.

Spacemonkey, a camera is not taking a picture of light alone. It works exactly like the eyes do. The lens is focused on the object that is reflecting that light, which means that the same image the eyes see is the same image that a photographer sees. It is assumed that the camera is taking a picture of light as it travels away from the object and strikes the lens (film), but that's not what is happening.

[Dragar]

Originally Posted by peacegirl

The eye has a field of view like a camera, but a camera's lens can focus on an object leaving the surrounding view out of focus. Eyes can't do that.

I don't understand this sentence. What do you mean by 'an object leaving the surrounding view out of focus'?

Originally Posted by peacegirl

The angle might not be changed, but the size of the object gets smaller and smaller until it is no longer in view. That's what I mean when I say walking a few steps away from the camera's field of view.

Then you are not using the words 'field of view' in the standard way, but thank you for clarifiying.

Your experiment still makes no sense though. When you say the following:

Originally Posted by peacegirl

If it turns out that the object cannot be seen outside of the field of view even though it's in the direct line of a camera, then it would mean that the light that is bouncing off of the object is not carrying the image of the object with it, or it would show up as an image on the lens

this is not true at all.

First of all (in the standard, accepted explanation - I do not know what Lessans said, and I'm sure it was different), light does not 'carry' an image; we create an image using light. Each point on the object reflects light which travels in a straight line from that point to our camera. By focusing the light onto a plane in the camera, we can map the relative locations the light came from - producing an image. In the case of the light falling on the retina, our brain interprets the locations the light falls onto the retina and we see the world in this way.

Second of all, if we cannot see an object because it has moved too far away, this is well understood (in the 'standard' scientific explanation). Usually this happens because:

a) There is too little light to form an image. There is only so much light being reflected out into the world, and so as we move further away, we get less and less of it (dropping off as the square of the distance). This can be (and is) resolved by using a bigger camera or a longer exposure time (or both).

b) The image size becomes comparable than the resolution of the detector on the focal plane. For instance, we have no hope of seeing something that produces an image on our retinas the size of only a few rods or cones. In a camera, the size of the pixels of a CCD determine the resolution. This can be resolved by using an appropriate lens to focus the light into a more appropriately sized image for our detector. Eventually we cannot even use this trick any more, due to the diffraction limit. Again, well understand and tested and used on a daily basis - and another thing that shouldn't work if we 'see' in the strange way you talk about.

These are well understood effects. Our explanation is well tested. We use them to build appropriately sized telescopes or microscopes. If we were wrong, they shouldn't work.

Your experiment won't show anything, because having a limit to the distance we can see something is understood and predicted by standard optics, so showing such a thing exists will confirm standard optics, not falsify it.

[peacegirl]

Originally Posted by LadyShea

Better. Does it still fit with what you are trying to describe when you say mirror images form on a lens?

Actually "strikes" is a better term because "forms" sounds as if time is involved.

[LadyShea]

Light has to travel to "strike" as well

[thedoc]

Originally Posted by peacegirl

The eye has a field of view like a camera, but a camera's lens can focus on an object leaving the surrounding view out of focus. Eyes can't do that.

OH YES THEY CAN, many times when looking at a particular object other objects at a different distance will be out of focus, most people just don't notice because they are concentrating on one particular item. Many times when you shift your sight from one object to another at a different distance it will take a short time for the eye to refocus on the other object. The eye does not see all objects at different distances in focus at the same time.

[LadyShea]

Here is what a professional photographer has to say

Originally Posted by Leo A. Geis

http://www.idahoairships.com/2007/09/03/the-circle-of-confusion-recognizing-the-limits-of-human-visual-acuity/

Finally, it should give you some idea of how incredibly convoluted the science behind our craft (photography) is. I will leave you with a challenging, very disturbing though: The technical underpinnings of the digital camera and lensing disciplines do not deeply scratch the surface of the body of knowledge concentrated on human vision.

[ceptimus]

Originally Posted by peacegirl

That's why I'm trying to define what I mean by "visual range". A visual range is the typical daylight range for a medium sized lens. Regardless of how laser lit a shiny fly is (I can't help but picture that poor fly all lit up ), there is a point at which that fly would be out of the field of view.

First, you're using the term 'field of view' in a non-standard way. Photographers and scientists use the term to mean the angle that the eye, camera, telescope, whatever covers. If an object is in the field of view, it just means that the eye, camera, whatever is pointing at that object and that the object could POTENTIALLY be seen or photographed. The object might be too small or too dim to actually be seen or photographed but it would still be in the field of view.

You would be better to use the term 'resolved' which I think is closer to what you mean. So a camera or eye could be looking towards a fly - the fly would then be in the field of view. If the fly can actually be seen/photographed, then we'd say the eye/camera is able to resolve the fly's image. If the fly is too far away, or too dimly lit to be seen/photographed, then we'd say the eye/camera was unable to resolve the image of the fly (or we might just say it couldn't resolve the fly, for short).

The unresolvable fly in the field of view may be able to be resolved by altering the conditions. If the fly isn't lit well enough we could light it better, or remove other light from the scene so that the fly shows a greater contrast to its background. If the whole scene is too dark to be resolved, then with a camera we could increase the exposure - allow the film or CCD to capture light over a period of many minutes or hours, till the image can be resolved. If the fly is too far away, then we could add extra lenses (effectively a telescope) to make the fly look bigger.

Note that when we add the extra lenses, we would change the field of view (I'm using the term 'field of view' in the accepted, angular sense here). Photographers speak of a 'wide angle lens' that captures an image with a wide field of view. The opposite kind of lens, a telephoto lens (see the reference to 'telescope' there?) apparently brings the photographed object closer, but at the same time narrows the field of view.

Second, you say 'A visual range is the typical daylight range for a medium sized lens'. Well, with a typical compact camera, in daylight, we can photograph mountains that may be 50 miles away; the moon (yes the moon can be seen during the day, sometimes) is a quarter of a million miles away; the sun is about 93 million miles away, and can, of course, be photographed.

So, in your terms, is the "visual range" for a medium sized lens a few yards, or a few miles or a few million miles? Let us know and we may begin to understand what you mean by the term.

[LadyShea]

Basic Photography
This course provides basic instruction on the following subjects: the principles associated with light, optics, cameras, light-sensitive materials

[peacegirl]

Originally Posted by Dragar

I don't understand this sentence. What do you mean by 'an object leaving the surrounding view out of focus'?

It's all about the aperture. We can't control our eye muscles to keep one aspect of our visual field focused, and the periphery unfocused, where a camera has the ability to do this.

Originally Posted by peacegirl

The angle might not be changed, but the size of the object gets smaller and smaller until it is no longer in view. That's what I mean when I say walking a few steps away from the camera's field of view.

Originally Posted by Dragar

Then you are not using the words 'field of view' in the standard way, but thank you for clarifiying.

You're welcome.

Originally Posted by Dragar

Your experiment still makes no sense though. When you say the following:

this is not true at all.

First of all (in the standard, accepted explanation - I do not know what Lessans said, and I'm sure it was different), light does not 'carry' an image; we create an image using light. Each point on the object reflects light which travels in a straight line from that point to our camera. By focusing the light onto a plane in the camera , we can map the relative locations the light came from - producing an image. In the case of the light falling on the retina, our brain interprets the locations the light falls onto the retina and we see the world in this way.

That's exactly what I've been saying. The only difference is the Sun's wavelengths do not change as objects in our environment absorb and reflect those photons. Our brain, looking through the eyes, or retina, sees the world in real time. Interpreting what we see is a secondary process. In other words, there is a difference between light being a condition of sight, and light (from the Sun) being a direct cause of sight. You're so close to understanding this, I hope you don't give up.

Originally Posted by Dragar

Second of all, if we cannot see an object because it has moved too far away, this is well understood (in the 'standard' scientific explanation). Usually this happens because

a) There is too little light to form an image. There is only so much light being reflected out into the world, and so as we move further away, we get less and less of it (dropping off as the square of the distance). This can be (and is) resolved by using a bigger camera or a longer exposure time (or both).

I thought reflected light goes on indefinitely as long as nothing absorbs it, or deflects it. Is this what you mean? If the lens is smaller it won't be able to gather as much light as we move further away, and therefore it could cut off the image? We're not talking about a large distance so whatever camera is appropriate we would use.

Originally Posted by Dragar

b) The image size becomes comparable than the resolution of the detector on the focal plane. For instance, we have no hope of seeing something that produces an image on our retinas the size of only a few rods or cones. In a camera, the size of the pixels of a CCD determine the resolution. This can be resolved by using an appropriate lens to focus the light into a more appropriately sized image for our detector. Eventually we cannot even use this trick any more, due to the diffraction limit. Again, well understand and tested and used on a daily basis - and another thing that shouldn't work if we 'see' in the strange way you talk about.

I'm not saying we should make something so small that we could not see it due to the size of only a few rods and cones. We're just talking about distance to see if the light contains the image.

Originally Posted by Dragar

These are well understood effects. We use them to build appropriately sized telescopes or microscopes.

Your experiment won't show anything, because having a limit to the distance we can see something is understood and predicted by standard optics, so showing such a thing exists will confirm standard optics, not falsify it.

You're right that it won't show anything, which is what I've been saying all along. Standard optics only confirms that the cones and rods have everything to do with how we see, but it does not confirm that the image is in the light itself and is traveling to the brain to be decoded.

[thedoc]

Originally Posted by ceptimus

First, you're using the term 'field of view' in a non-standard way. Photographers and scientists use the term to mean the angle that the eye, camera, telescope, whatever covers. If an object is in the field of view, it just means that the eye, camera, whatever is pointing at that object and that the object could POTENTIALLY be seen or photographed. The object might be too small or too dim to actually be seen or photographed but it would still be in the field of view.

You would be better to use the term 'resolved' which I think is closer to what you mean. So a camera or eye could be looking towards a fly - the fly would then be in the field of view. If the fly can actually be seen/photographed, then we'd say the eye/camera is able to resolve the fly's image. If the fly is too far away, or too dimly lit to be seen/photographed, then we'd say the eye/camera was unable to resolve the image of the fly (or we might just say it couldn't resolve the fly, for short).

The unresolvable fly in the field of view may be able to be resolved by altering the conditions. If the fly isn't lit well enough we could light it better, or remove other light from the scene so that the fly shows a greater contrast to its background. If the whole scene is too dark to be resolved, then with a camera we could increase the exposure - allow the film or CCD to capture light over a period of many minutes or hours, till the image can be resolved. If the fly is too far away, then we could add extra lenses (effectively a telescope) to make the fly look bigger.

Note that when we add the extra lenses, we would change the field of view (I'm using the term 'field of view' in the accepted, angular sense here). Photographers speak of a 'wide angle lens' that captures an image with a wide field of view. The opposite kind of lens, a telephoto lens (see the reference to 'telescope' there?) apparently brings the photographed object closer, but at the same time narrows the field of view.

There is also the matter of focus if the lens is focused too distant or too near it may not be able to resolve the image of the fly. Here depth of field comes into play with a large appature the depth of field is shorter and the object may be far out side of the field to be in focus.

[Dragar]

Originally Posted by peacegirl

It's all about the aperture. We can't control our eye muscles to keep one aspect of our visual field focused, and the periphery unfocused, where a camera has the ability to do this.

Yes, we can. Hold your hand up in front of your face. Focus on your hand. Note that objects in the periphery are unfocused. And vice-versa.

Originally Posted by peacegirl

I thought reflected light goes on indefinitely as long as nothing absorbs it, or deflects it. Is this what you mean? If the lens is smaller it won't be able to gather as much light as we move further away, and therefore it could cut off the image? We're not talking about a large distance so whatever camera is appropriate we would use.

Yes. The light does go indefinitely on, however the light from (roughly) each point on the object will not quite be reflected in the same direction. Very close to the object, we get most of the light. Further away, the paths of light rays have diverged, and we do not get as much light. It does not 'cut off' the image so much as just leave it undetected. A camera film would not have enough photons to react chemically, a CCD would not trigger enough responses. There might be a very faint image, or no image at all, depending on how little light is received.

A good way to picture this is to imagine the light travelling out from the object in the form of an expanding sphere. The same number of photons must cover the surface of the sphere as the radius expands, but the surface of the sphere increases as the radius expands. Therefore the density of photons on the surface of the sphere decreases with the radius. Likewise, a camera (sampling only a small fraction of the surface) will receive less photons if it is further away.

Originally Posted by peacegirl

You're right that it won't show anything..

Then why propose the experiment?!