Which telescope provides a larger field of view?

Which telescope provides a larger field of view?

• A. Keplerian
• B. Galilean
• C. Neither
• D. Both

Answer: (A)

The ability to see a wider scene through a telescope mainly depends on how the eyepiece handles the light rays coming from the objective. In a Keplerian setup both lenses are converging, so the objective forms a real intermediate image that the eyepiece magnifies. This design can use a larger portion of the objective’s light cone without clipping the edge rays, which lets more of the scene be seen at once. In contrast, a Galilean setup uses a diverging eyepiece, which tends to clip the outer rays and limits how wide a field can be viewed, especially at higher magnifications. So the Keplerian arrangement provides a larger field of view.

The ability to see a wider scene through a telescope mainly depends on how the eyepiece handles the light rays coming from the objective. In a Keplerian setup both lenses are converging, so the objective forms a real intermediate image that the eyepiece magnifies. This design can use a larger portion of the objective’s light cone without clipping the edge rays, which lets more of the scene be seen at once. In contrast, a Galilean setup uses a diverging eyepiece, which tends to clip the outer rays and limits how wide a field can be viewed, especially at higher magnifications. So the Keplerian arrangement provides a larger field of view.