"unless it is part of a commissioned assignment or project carried out by a professional photographer, in which case I believe whoever puts the money down and makes the contract for the work has the copyright."
Not in the UK (I don't _think_ the putative republic of Alba has different laws yet). Unless the copyright is specifically assigned, copyright remains with the photographer regardless of why the picture was taken.
For example I pay the Bounty photographer for pictures of my crotch goblins in hospital... unless Bounty specifcally give me permission I cannot legally get copies of those pictures made by a third party. As it happens the last lot came with a 'here are the pictures as full resolution JPG (yes... I know), you have permsiion to do with them as you will' letter as well as the download link.
coat becasue who needs to know about crotch goblins in an IT thread?