Changing field of view of rendered image has no effect

[shaharyuval]

I'm trying to render a mesh using orthographic projection. I read that this is possible by setting the field of view to 5 degrees (not sure this is true). However, I do not see any effect when I change the field of view:

import open3d as o3d

def __init__(self):
        # initialize a persistent visualizer in the application constructor
        self.vis = o3d.visualization.Visualizer()
        self.vis.create_window(width=self.output_size[0], height=self.output_size[1], visible=False)
...
def _render(self, mesh):
        # rendering code:
        self.vis.add_geometry(mesh)

        # adjust fov per frame
        ctr = self.vis.get_view_control()
        current_fov = ctr.get_field_of_view()
        fov_step = self.target_fov - current_fov # for example self.target_fov == 5
        ctr.change_field_of_view(step=fov_step)

        self.vis.poll_events()
        self.vis.update_renderer()
        img = self.vis.capture_screen_float_buffer(do_render=True)
        img = np.array(img)
        img = np.round(img * 255).astype(np.uint8)

        self.vis.remove_geometry(mesh)
        return img

Trying this code with self.target_fov = 60 and 5 results in the same rendered image. Why is there no effect?

[shaharyuval]

This appears to be related to the following bug: #6009

I'm modifying a copy rather than the real view control.

As suggested in other discussions, downgrading to Open3D version 0.16.0 resolves this issue.