Refers to a single eye, often in contrast to both eyes or in contexts like one-eyed creatures or people.
その怪物は額に一眼しか持っていなかった。
The monster had only one eye on its forehead.
I photographed the travel scenery with a single-lens reflex camera.
single-lens reflex camera
Abbreviation of 一眼レフ (single-lens reflex camera). Used in photography contexts.
See also: 一眼レフ
彼は新しい一眼を買って、週末に撮影に出かけた。
He bought a new single-lens reflex camera and went out shooting on the weekend.
In the game of Go, a group of stones with only one eye, which is vulnerable to capture.
See also: 眼 (がん)
この石の集まりは一眼しかないので、取られる危険がある。
This group of stones has only one eye, so it is in danger of being captured.
This group of stones is dangerous because it has only one eye.
単眼 is a more technical or biological term for a single eye, while 一眼 is used more generally, including in casual contexts.
一眼 is the common shortened form of 一眼レフ (single-lens reflex camera), but on its own 一眼 can also mean simply 'one eye' or a Go term, so context decides the meaning.
SLR camera; single-lens reflex camera
mirrorless camera; mirrorless interchangeable-lens camera
Compound of 一 (one) and 眼 (eye). The camera sense is a clipping of 一眼レフ.