having seen the yard stick photo and measured my own cats I'm going with this. If it's a mountain lion it is a tiny one. The yard stick in that spot shows the cat to be about 26" or so nose to tail base if you stretched it out of that hunched position (please, no photoshop necessary). So it's either a very young, still with momma lion, or it is a large domestic. With my Dapper and Brendan's Schmutz just a few inches shorter I think that it is definitely possible for a domestic to be that large. Just for arguments sake I will add that the "tufts" people see could just indicate that it is a domestic medium hair cat. My DMH Princess definitely looks like she has cheek tufts because that is one of the places her hair is the longest. If the cat in the photo is a DMH it would appear bigger because of the extra fluff.
Now, also, the way that game cams work, or most anyways (maybe it's not the case with this one) is that they take a pic every 30 seconds by motion detection. If mystery cat had stayed to drink at the pond there would have been more photos. If mystery cat and a momma lion had come around momma would have drunk at the pond as well getting her pic on there. On our game cam when a cat walks by the camera we generally get a blank pic or half a cat exiting because our cameras trigger speed isn't that good (what do you want for a $50 game cam). Being as how this cam only took one pic of mystery cat it shows that he/she came in and out in less than 30 seconds and was probably just traveling from one side of the pond and into the yard beyond and likely quite slowly, very possibly paused on that rock, maybe watching fish (unless this is a really good/expensive trail cam we are seeing pics from). Trail cams are designed to take pics of game in an area over many days/weeks. Trigger speed varies wildly, our camera's trigger speed is about 5 seconds. We've got plenty of lovely pics of deer and turkeys with it. Unfortunately we have erased the pics of the cats we have gotten because it's the game photos we are after but it does make them look awfully large at night if they are light colored.
I can't remember what the OP said was the distance from the camera to the cat but I know our trail cam is designed to take pics of animals at an ideal distance of 15'. When they are closer to the camera than that the flash glares on them making them appear larger as well. Too bad I don't have the pic of my hubby as Godzilla from one night, lol. He was only 8' from the cam and wearing light jeans and a light colored jacket. Because the frame on the pictures isn't very big it made him look huge, especially in comparison to the landmarks behind him, lol. But again, we only keep the game pics (though we do have one daytime shot of DH standing in the photo for scaling the deer, but he is at 20' in that pic.
So to weigh in I'm going to go with Domestic with the possible influence of cross breeding to a bob.