I was putting up some wall decorations earlier today and was painstakingly realigning everything until it looked level to my eyes. It might be just a hair off, but if I don’t correct it, I’ll see the misalignment almost instantly and get bothered for the rest of time until I fix it. Has anyone investigated, or is there literature on the minimum perceptible angle from level to the naked eye?
That’s actually a pretty good question.
With no exact answer, I do think this will at least in part depend on relative comparison to how exactly level your floor/ceiling/counter/table or other frame of reference is, which itself might not be perfect.
Side note, basically every smart phone out there has orientation sensors, so it should be just as easy as downloading a Bubble Level app from the app store.
not when almost every phone has a camera bump, volume rockers and a power button.
i.e. no long flat sides, that still allow you to see the screen.