The absence of McCaig's Tower suggests an early date for this picture:-
The boat in the foreground (behind the caption "Oban from North" - actually it's from the north west) has no masts and what appears to be a crane so I'm guessing it was a coal hulk - i.e. a floating coal depot for refuelling steam-ships. But coal (for steam ships and trains) would presumably have come on the railway so does this suggest a date before 1880 which was when the railway reached Oban?
Also, the photo appears to have been taken from a very high vantage point. If taken from a high point on Kerrera (the island which forms the west side of Oban bay), I feel you would be able to see some Kerrera shore in the foreground. So was the picture perhaps taken from the top of the mast of a sailing ship? If it was, I can’t help thinking the ship must have been awful close to Kerrera!