focus
The muffler is in focus.
If you take the photo from the side and place the center of the photo on the bar, everything should be clear. Most cameras that use an auto focus work off an area in the center. Should get several teeth in focus, not just one.
Square filed means very sharp, more prone to kick back, abused easier. It can behave similar to an over sharpened round filed tooth. (Where you've got a groove going too deep and have a little too much hook)
In the West, most of the time you'll see square filed used by professional loggers and not firewood cutters. The later spend too much time cuttin' dirt.
Same applies to fire fighters. Dirt, which dulls any standard chain, really affects square filed.
Square filed is harder to file in the field.
