A documentary by Liz Marshall. Unrated. Opens Friday, August 2, at the Vancity Theatre

A worthy subject is aired in The Ghosts in Our Machine: the mistreatment of animals in this increasingly mechanized culture. The documentary focuses on Jo-Anne McArthur, a talented photographer who has dedicated herself to capturing harshly revealing images of creatures kept for our pleasure, not theirs.

The images she grabs, of animals trapped in fur-farm cages, testing labs, or slaughterhouse-bound trucks, are technically strong and full of empathetic, sometimes harrowing feeling. And Toronto writer-director Liz Marshall, who previously made a doc about the commodification of water, is her own cinematographer. Marshall (who’ll speak at an August 7 screening here) matches McArthur in creative, colourful lensing, and the darker material is aided by cool music from Radiohead and composer Bob Wiseman.

Also helpful are sections depicting a few Ontario sanctuaries and adoptive homes where rescued animals (including “spent” dairy cows and laboratory-bred beagles) are given the kind of lives they deserve.

The doc starts with the premise that we are animals too, not quasi-angels given godly domain over “lower” life forms. On the downside, it’s essentially a half-hour’s worth of movie padded out to three times that length. In several cases, we see the photographer planning a picture-taking mission, footage of the mission itself (often a clandestine, even dangerous undertaking), then the resultant pictures, followed by extended scenes of McArthur discussing these photos with like-minded editors and friends.

The effect is that of being stuck in an earnest echo chamber alongside a less-than-articulate tour guide who tends to undermine her boldest statements with questioning inflections?

Ghosts would benefit by being edited down to its bare essentials and slipped into TV slots where it could have some real effect on people who have barely thought about the many strained relationships with our animal buddies.