It's possible for a telescope to have three lenses, but it's not the most common configuration. Here's a breakdown:

* Common Configurations:

* Refracting Telescopes: These telescopes use only two lenses: an objective lens (the large lens at the front) and an eyepiece lens.

* Reflecting Telescopes: These telescopes use a primary mirror and a secondary mirror, with the eyepiece lens being a separate component.

* Telescopes with Three Lenses:

* Apochromatic Refractors: These high-end refractors often use a third lens (usually a special glass type) to correct chromatic aberration, a color fringing effect that can occur in standard refractors. This results in sharper images and better color accuracy.

* Lens-Mirror Telescopes: Some designs combine a lens with a mirror, creating a hybrid telescope. For example, the Schmidt-Cassegrain telescope uses a corrector plate (lens) at the front of the telescope to improve image quality.

So, while not typical, having three lenses in a telescope can be done, especially in specialized designs that aim for improved performance.