I don't understand why anyone would want to snap a photo of their in-game actions, but it seems to be popular.
And the latest patch for Middle-earth: Shadow of Mordor offers players a chance to enable a new photo-taking mode.
You can remove the UI from the scree and tweak various settings, such as depth of field, tilt and field of view. But as GameSpot notes, you can't actually capture and save the photo. There's a tutorial – which tells you to enable the mode in the Settings menu – and you can tweak photo settings, but you can't save the photo itself. That seems weird.
But hey, if you're playing on the PlayStation 4, just hit that handy-dandy Share button and save it that way. Not sure what you'll do on the Xbox One. By the way, if you haven't tried it yet, Middle-earth: Shadow of Mordor is one helluva fun game.
Related Game(s): Middle-earth: Shadow of Mordor