What does this mean in relation to a lens?

[Daniel D. Teoli Jr.]

"...minimizing the appearance of breathing when changing focus."

 

[M Joel W]

1 hour ago, Daniel D. Teoli Jr. said:

"...minimizing the appearance of breathing when changing focus."

 

A lens's focal length is the distance between the optical center of the lens and the film back when the lens is focused on infinity.

(I think?)

When you change focus to focus on closer distances, you're moving the lens forward and effectively "zooming in." At least with most standard unit focusing lenses... with my old Nikon still lenses, I notice they zoom in as I move toward "macro" mode. Very slightly. The effective f-stop also decreases but only slightly. Which is why there's exposure compensation for macro and for large format.

A lens designed to minimize breathing minimizes zooming in or zooming out when you change focus. Perhaps the lens zooms out a bit as it focuses close.

[Max Field]

Short answer is; breathing is the slight zooming of the image that appears when pulling focus.

Expensive lenses tend to have less breathing.

[Kyryll Sobolev]

51 minutes ago, M Joel W said:

A lens's focal length is the distance between the optical center of the lens and the film back when the lens is focused on infinity.

(I think?)

focal length is the distance between rear nodal point to the point where light crosses the optical centre axis of the lens (which at infinity is the plane/film/sensor)

[M Joel W]

Just now, Kyryll Sobolev said:

focal length is the distance between rear nodal point to the point where light crosses the optical centre axis of the lens (which at infinity is the plane/film/sensor)

Thanks. Yeah I wasn't sure about that one.