These shots were taken on separate days with the same 400mm lens attached to a Panasonic G1.
The shot on the left was taken on a day when the temperature was 27 deg. C. The roof
shot was about 500ft away. The shot at right was taken on a day when the temp was 18 deg. C.
While you can see the beginnings of resolution of the gravel in the asphalt on the right
hand shot, the left hand shot is blurred out. Three things contribute to degradation of
resolution: The focal length of the lens, the heat waves in the day and the diameter of
the front lens of the telephoto lens. The larger the diameter of the lens, the more
susceptible to the effects of heat waves.