Everyone makes mistakes from time to time. Sometimes you lock your keys in the car. Sometimes you leave the sandwich too close to the counter edge with furry burglar nearby. Either way, we all do it.
The other night I was shooting landscapes in one of my favorite spots on top of Austin at the Pennybacker bridge.
The night was awesome. Stars out, cool breeze, not too chilly for Texas winter. I had my tripod setup, camera was locked down, shutter speed dialed in to about 8 seconds, perfect. I was trying to catch some stars and light trails in the viewfinder since we have a new moon. My setup was awesome, at least I thought.
When I looked in the 3" LCD the pics were looking so awesome.
The answer is a resounding yes! I did some testing just now and found out that even objects 15 to 20 ft away could have a different spot on the infinity symbol even though they are all more than 3 ft away. (a common myth is that anything farther than 3ft away on a wide angle zoom you can just set the focus ring to infinity and it will be sharp)
I found out my ring is dead center on the money for focus. Everything farther than 3ft or for example in the picture above should have been focused dead on the infinity symbol. The margin of error is so small that even .5 to 1 mm left or right made a fuzzy exposure. See below.
The moral of the story is this - Check the focusing on your wide angles in the daytime and make a mental note or keep something in your camera bag that shows where infinity focus is for that lens.