Magnification - Yousef's Notes

How the size of the object changes in the image.

$m$: magnification factor $f$: focal length $z_0$: distance of the object from pinhole

[!Note] Image size is inversely proportional to distance.

[!Tip] there could be a small numerical multiple-choice question regarding this.

If $z_0$ is too small, different magnification factors will be applied to different points of the image.

In other words: if the depth of an object is much smaller than the average depth of an image, the magnification for the object can be considered constant:

$$ \Delta z < \tilde{z} $$

If $z_0$ is too large (i.e. the object is far away), you can assume the rays come parallel to the optical axis. (orthographic projection)