Quote Originally Posted by Dan Fromm View Post
Aren't the vertical edges of the frame parallel to each other and to a vertical line anywhere on the GG?
To each other and to the GG... yes.

To vertical lines on the subject... maybe, maybe not, depending on where the feature is and whether the camera is level.

A vertical line through the center of the viewfinder will always align with a centered subject feature
if the camera is level, regardless of camera tilt.

If you tilt the camera up, building edges away from the image center will converge toward the top.

Also, some lenses may introduce distortion near the edges.

- Leigh