I am using a 400 mm. lens with a crop factor of 1.6, what that means or what i am telling you is i am quite a distance from this pair. They are still arranging the nest and bringing materials and getting it just right as egg laying is not to far off. It wasn’t so long ago i wouldn’t have dreamed that i would get to photograph a nesting pair of bald eagles in Wisconsin. So amazing are these birds and for the most part very tolerant of us humans. I know of more than one eagle nest right in the city. I photographed this near Appleton,Wisconsin 2-08-2013. I used my Canon 7D with a Canon 100-400 mm. lens.