The equation for mirrors is identical, except that zi represents the distance of the image created by reflected (not refracted) light rays. Also, f can be made negative to represent a concave lens (or convex mirror), in which case the image is "virtual." This means that the light rays do not actually converge at that location, even though it appears that way to an observer on the other side of the lens/mirror.
CelticsPwn
This was a really good source that I used in high school optics to remember what type of image forms depending on where the object is located in relation to the location of the focal point and the location of 2 x the focal point: https://www.physicsclassroom.com/class/refrn/Lesson-5/Converging-Lenses-Object-Image-Relations
The equation for mirrors is identical, except that zi represents the distance of the image created by reflected (not refracted) light rays. Also, f can be made negative to represent a concave lens (or convex mirror), in which case the image is "virtual." This means that the light rays do not actually converge at that location, even though it appears that way to an observer on the other side of the lens/mirror.
This was a really good source that I used in high school optics to remember what type of image forms depending on where the object is located in relation to the location of the focal point and the location of 2 x the focal point: https://www.physicsclassroom.com/class/refrn/Lesson-5/Converging-Lenses-Object-Image-Relations