I've got a Panasonic Lumix FZ72: a 20-1200mm superzoom. It's pretty good, and has pretty decent image quality for the price.
Unfortunately, I've noticed that if I take any pictures past roughly 400mm of anything more than a kilometer away, the images get "mushy". I doubt that it's the lens, given that I've taken fairly decent pictures up to 1200mm on the same camera. That must mean that I'm seeing atmospheric effects. But I'm seeing this "mushy effect" at only 400mm in a town with pretty clean air. So what gives?
Am I seeing atmospheric effects? When can I generally expect to see them?
This is an image taken at 402mm, about 1.7km from the subject. If you zoom in, you can see that the image is slightly "mushy".
Another image I took at 402mm, no atmospheric effects, subject about a meter from the camera.
An image I took at 145mm, again no atmospheric effects visible as the flowers were right in front of the camera.