What Do You See When Replacing a Screen with Your Eyes for a Real Image?

[pivoxa15]

No, you are not looking for an image on the pencil. You are using parallax to locate the image. Hold the pencil between your eye and the lens, move your head side to side, you should be able to observe relative motion between the image and the pencil. Move back and forth between your eye and the lens until you find a spot where the image and pencil have no relative motion. The pencil will then be in the same distance from the lens as the image. If you replace the pencil with a screen you should see the image on the screen.

I see now. I did it and found a place where the image was 'stuck' on the pen as I moved my head across. Quite an amazing thing. I should look more into the theory of it.

 

[pivoxa15]

If the image is inverted it's a real image in front of the lens, and it should behave more or less as I described.

How would a movie projector (which projects motion pictures onto the wall) work? If the picture was projected normally, like light from objects shining through a magnifying glass, it would register on the screen as an inverted image. Hence it will reflect off the screen into the viewer (siting beside the projector) also thinking the image is inverted. So does a movie projector must project motion pictures which are inverted?

 

[snbose]

Fascinating, jt. Would each eye receive the same image, or would parallax hold true to produce a 3-d picture?

This is a good experiment.
1. Parallax would perfectly hold true with the floating-real image. You can actually hold a pencil where the image originally appeared (before you removed the screen) and move your head sideways and the pencil's position to detect the exact location of the image. However you need to place your eyes (or screen) in the path of the refracted light rays. Now imagine you step forward from this position and try to see the real image from a different angle/position where you are not in the path of the rays that formed the image - and also there is no screen. Will you still see the image there? Of course not.

2. 3-D picture. My best guess here is : Yes and No. Depending on the distance of the object from the lens. Both eyes will always see the same thing but that does not mean the image will be 3D.

Case A: If the object is very far way: Then the image will be formed on the focal plane of the lens and will be 2-d even though both the eyes will see the same image. Its just like seeing the image on a 2-d screen.

Case B: If the objects are closer then images will form at different distances from the lens depending on the object-distance. In this case the real images will have the same (or similar) 3-d effect as the objects. So the original 3d-ism of the objects will be somewhat preserved among the real images.

 

[jtbell]

So does a movie projector must project motion pictures which are inverted?

I've used 35mm slide film (transparency) projectors and have always had to insert the slide upside down in order to get the image on the screen to come out right side up. I don't know whether this is also true of movie projectors. Some might have a more complicated optical system that inverts twice.

 

[pivoxa15]

Is there usually no difference between seeing (directly) a real and virtual image except that the real is inverted?

directly - means light directly off a mirror or lens, like seeing the image directly off the projector if possible. And not after it reflects off another screen or mirror of some sort.

If so than it means seeing a real image is just as if seeing a virtual image except the object is inverted in front of you, which could be behind the mirror or in front of the lens. I have observed the reflection off a spoon and the image off the concave and convex sides are of the same general nature - that is its as if there is an object on the other side of the spoon hence like seeing a virtual image except on one side its inverted and the other not.

Or does this (the virtual nature of both images) not matter because the fact that the image entering your eyes is inverted imply its a real image. This is the only feature which differentiates a real and virtual image when viewing them directly?

 

[pivoxa15]

I've used 35mm slide film (transparency) projectors and have always had to insert the slide upside down in order to get the image on the screen to come out right side up. I don't know whether this is also true of movie projectors. Some might have a more complicated optical system that inverts twice.

I take it that the picture registered on the film inside a camera is also up side down.

What happens if a picture is taken of an object that is inside the focal length of the lens of a camera? It would be a virtual image which would be troubling?

 

[CPL.Luke]

hasn't anybody here seen a ruler go near a large converging mirror? or anyone of the "magic" boxes?

if you use a large mirror you actually see another object coming out of the mirror. As an example, if you move meter stick towards the mirror, anouther meter stick will seem to emerge from the mirror to come out and touch the real meter stick. Its very cool to see.

 

[pivoxa15]

hasn't anybody here seen a ruler go near a large converging mirror? or anyone of the "magic" boxes?

You are talking about a virtual image?

if you use a large mirror you actually see another object coming out of the mirror. As an example, if you move meter stick towards the mirror, anouther meter stick will seem to emerge from the mirror to come out and touch the real meter stick. Its very cool to see.

It happens in every plane mirror that the closer you put the object to it the closer the virtual image is to the mirror on the other side creating the effect you are talking about. Is this what you mean?