equivalent focal length

British  

noun

1. optics the ratio of the size of an image of a small distant object near the optical axis to the angular distance of the object in radians

---

Example Sentences

The telephoto camera remains exclusive to the 13 Pro phones, and Apple has increased its equivalent focal length to 77mm, or three times longer than the primary camera.

From The Verge • Sep. 15, 2021

It starts with a gigantic 1/1.7-inch Exmor RS 12-megapixel sensor set behind a Zeiss lens at a 24mm equivalent focal length.

From The Verge • Jul. 13, 2020

Even when attached to a telescope giving an equivalent focal length of nearly 150 feet, the camera only gives a very tiny image of the planet.

From To Mars via The Moon An Astronomical Story by Wicks, Mark

The sharpness of the images given by the new telescope may be illustrated by some recent photographs of the moon, obtained with an equivalent focal length of 134 feet.

From The New Heavens by Hale, George Ellery

The equivalent focal length of a positive or Ramsden eyepiece is equal to three fourths of the focal length of either of the lenses.

From Pleasures of the telescope An Illustrated Guide for Amateur Astronomers and a Popular Description of the Chief Wonders of the Heavens for General Readers by Serviss, Garrett Putman