1. Below is a schematic representation of the construction and operation of a particular type of telescope. You can see here that each ray of light passes through a lens,and is then reflected twice by a mirror

Therefore which one of these statements are correct explain why

1. The curved lens in this case is a divergence lens.
2. The lens is only used for filtering the incident light.
3. Because the focal point is outside the telescope, you have a sharper image.
4. This construction is mainly used to reduce the length of the telescope