Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free.

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?

share|improve this question

1 Answer 1

up vote 4 down vote accepted

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.

share|improve this answer
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? –  Jack M Apr 16 '13 at 16:23
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. –  Ben Crowell Apr 16 '13 at 23:03
I wish I had a convex lens on me to test it out, but thanks. –  Jack M Apr 17 '13 at 10:19
@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. –  supercat Jan 20 at 20:30

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.