Eyepiece

Definition

The eyepiece is the lens or group of lenses in a telescope through which the observer views the magnified image. It plays a crucial role in determining the magnification and clarity of the observed celestial objects.

5 Must Know Facts For Your Next Test

1. The eyepiece works with the objective lens or mirror to magnify the image produced by the telescope.
2. Eyepieces come in various designs, such as Huygens, Ramsden, and Plössl, each offering different levels of eye relief and field of view.
3. The focal length of an eyepiece is key to calculating telescope magnification; it is done by dividing the focal length of the telescope by that of the eyepiece.
4. Choosing an eyepiece with a longer focal length results in lower magnification but a wider field of view.
5. A Barlow lens can be used with an eyepiece to effectively double its focal length and therefore increase magnification.

Review Questions

• What is the primary function of an eyepiece in a telescope?
• How do you calculate the magnification provided by an eyepiece?
• Name two different types of eyepieces and describe one advantage for each.

Related terms

Objective Lens:

The main lens or mirror in a telescope that gathers light from distant objects and focuses it to create an image.

Focal Length:

The distance between the lens or mirror and the point where it brings light to focus, important for determining magnification.

Barlow Lens: An accessory that increases the effective focal length of a telescope's optics, thereby increasing its magnifying power.