Glasses lens doesnt flip image. WTF?

[slash112]

How come the lenses in glasses don't flip the image? A ray diagram of any lens would suggest that it should. I just don't get it.

[Xei]

Well, horizontal rays go through the lens and then are bent towards each other. If you're close enough to the lens the rays are still the right way round but form a smaller image; if you're far away enough from the lens the rays meet and then cross over and so they will be upside down.

[slash112]

yea, that would make sense on a ray diagram. something about if the object is further away than the distance of the focal length, then the image focuses on the other side of the lens or some shit like that. but it's just that I remember looking through glasses at all different distances, and im sure it was upright the whole time... wait... or was it? hmmm, im gunna check tomorrow. thanks

[Sesquipedalian]

I think that the magnification is so small that it would take a long distance for this to happen. The point of glasses is to bend the light just enough that the lens in the eye can focus the images comfortably, without strain. The focus would be moved on the order of millimeters or less. The only way that this image flip could happen, in my mind at least, is for the person to be nearly legally blind, and you seeing the image with the glasses 5+ feet away. One more point to add: Were the glasses for someone near or far-sighted? If I have my facts straight, someone near sighted would never have the flip (concave lenses) and far sighted might, under extreme circumstances. (convex)