# Conceptual optics: what if I am not at image-forming distance?

Take the following optical arrange for a concave mirror:

Where the letters stand for Object, Image, Focus, Center

For it, we can use the equation below to calculate image distance formation:

$$\large x_o^{-1}+x_i^{-1}=f^{-1}$$

where $x$ stands for distance to the mirror, $o$ for object $i$ for image.

Question

Do we need to be exactly on the beams intersection ($x_i$) to see the image?

I'm not very familiar with curve mirrors, but it doesn't make sense in my head, as objects can be seen with us standing on different positions.

• Geometric optics is not my strong suit but isn't the statement that the image is formed at x_i just a statement that if you look there appears to be an object at the point in space? – jacob1729 May 17 '18 at 17:48
• @jacob1729 nice, im not sure. I think is the point where, if you put the eye, you see an image, but not if you are apart from it... – user153036 May 17 '18 at 17:52
• The image point is where all rays come to a single focus. If you are away from it, you can't get a clear image... except our eyes are better than that and given two diverging rays will trace them back to work out the source. I think the image should act like a point source in this case. Will be good if someone comes along with a nice answer though. – jacob1729 May 17 '18 at 17:55