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When light from an object passes through a convex lense, it gets reconverged at a single real image. From there, the light rays presumabely begin diverging again, exactly as if there was a light-emitting object sitting at the real image point.

Why is it that if we look at the real image point, we don't see a hologram of the object sitting there?

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2 Answers 2

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You're operating under a misconception. When a real image is formed, we can see it, provided that our eye is positioned in a location such that rays from the image can enter your eye. Compared to a hologram, the situation is different for a couple of reasons. (1) The possible locations of your eye are more restricted. (2) You may pick up psychological cues such as the framing of the field of view, which cause your brain not to interpret the real image as being where it actually is.

By the way, the word is spelled "lens," not "lense," and it is not always true that a convex lens produces a real image.

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    $\begingroup$ But I was in an optics lab this morning working with convergent lenses, I didn't notice an apparant object floating at the real image point. Are you saying that had I put my eye right on the optical axis, I would have? $\endgroup$
    – Jack M
    Commented Apr 16, 2013 at 16:23
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    $\begingroup$ Yes. Your eye would also have to be far enough from the image to allow you to focus on it. Because of the psychological cues referred to my answer, it might not actually seem to you like it was floating there. $\endgroup$
    – user4552
    Commented Apr 16, 2013 at 23:03
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    $\begingroup$ I wish I had a convex lens on me to test it out, but thanks. $\endgroup$
    – Jack M
    Commented Apr 17, 2013 at 10:19
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    $\begingroup$ @BenCrowell: If a film projector is placed so that its image goes past the edge of the screen, and a person stands some distance "behind" the screen so part of the image hits his face as he looks at the projector, the portion of his field of view which is occupied by the projector lens will appear to contain the part of the image which lies between the viewer and the lens. $\endgroup$
    – supercat
    Commented Jan 20, 2015 at 20:30
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It's not exactly the same as if an actual object was sitting there. An actual object emits light in all directions but the light from the focal point only travels in a straight line from the surface of the mirror, through the focal point. If you place a screen at the focal point you will see an image on the screen. You could also position your eye at the focal point, at which time you will see an image in the mirror.

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