Dog eyesight, scientific question.

[FiF]

Somewhat long post before I get to the question sorry.

Someone recently sent me a link to a thread in Reddit to show me this old photograph.



Like PH the thread here developed into an argument, meh photoshop, etc etc.

Then lead to a thread discussing dogs seeing underwater here with a couple of really good answers.

Anyway was reminded of this today when on his morning walk by the river the dog was clearly watching something in the river. He was standing on the bank, and his actions are typical of when he has seen and is watching something closely, yet I couldn't see anything, even down at his level. Part of the problem was the water was a bit murky, but not especially so, but main issue was reflected light from the surface. Dog doesn't wear Polaroid sunnies, so wondering what he was seeing or had detected. At one point, some time after he'd started watching a small trail of bubbles came to surface, so makes me think something was there.

Any ideas?

[FiF]

Funnily he does that off a beach higher up the river, sticks his head under the water and fetches one of those toys used to train kids to swim underwater in a pool. So clearly they can see better than perhaps we think.

I know dogs are supposed to have eyesight that isn't so acute, but other owners have commented on how quickly he picks up on stuff at a long distance, which we thought was the case but nice to have it confirmed.