It uses a 15km radius MapZone as the photo area, and you need something that can do 200 renown points - that "Photo value" of 20 is 10% of that... then as suggested, you need to be locked onto the proper target. It should only take one picture to complete the mission. Anything you can lock onto that is worth 200 points or more, should fulfill the Objective. But, a DD might only be worth 120-150 points, but something like a Nippon tanker would be worth 400 points... While the orders insinutate "anything", it really has to be either a cruiser or larger, or a medium merchant or larger...
