What is the nature of the final image formed by an astronomical telescope compared to the object?

The image formed by a lens is always erect and diminished. What is the nature of the lens?

The figure below shows an object $AB$ placed on the principal axis of a lens $L$. The two foci of the lens are $F_1$ and $F_2$. The image formed by the lens is erect,virtual and diminished. Copy the diagram and answer the following questions: $(i)$ Draw the outline of the lens $(L)$ used. $(ii)$ Draw a ray from $B$ passing through $O$. Show the ray after refraction by the lens. $(iii)$ Draw a ray of light starting from $B$,which after passing parallel to the principal axis,is incident on the lens and emerges after refraction from it. $(iv)$ Locate the final image formed.

Draw ray diagrams showing the image formation by a concave lens when an object is placed:
$(a)$ at the focus of the lens
$(b)$ between focus and twice the focal length of the lens
$(c)$ beyond twice the focal length of the lens

If a convex lens forms a real and magnified image of an object,where is the object placed?

What type of image is formed by a plane mirror?