Multiple telescopes are sometimes independently pointed at the same object, either to increase the total light-gathering power, or to provide simultaneous observations with complementary instruments.

All the new ground-based telescopes greatly exceed the light-gathering power of the Hubble telescope, which is a relatively small instrument.

A smaller mirror means less light-gathering power, and less spatial resolution, compared to a larger mirror.

The 40-inch (1,016-mm) lens has a light-gathering power about 35,000 times greater than that of the human eye, and can magnify an object 2,000 times.

For example, a telescope with a lens which has a diameter three times that of another will have nine times the light-gathering power.

The closed tube stays clean, and the primary is protected, at the cost of some loss of light-gathering power.

It would have a light-gathering power comparable to that of the European 16-meter telescope.

The combined light-gathering power of the four 8-meter mirrors will be the same as that of a single mirror 16 meters in diameter.

A 100-meter telescope, with another tenfold increase in light-gathering power and even sharper images, he said, would be "extremely powerful."

The main purpose was the increasing of light-gathering power and diminution of aberration.