I discovered Thompson Beach Road in Heislerville, NJ by accident. I knew it was there from my trips to Heislerville Fish and Wildlife Management Area, but I had no idea it was THE spot for Osprey in Cumberland County. There may be up to a half-dozen sitting in the trees along the road at any one time.
You can get some good photographs with only a 400mm lens, as there is an occupied nest directly on the road. With the mother incubating her eggs right now, I chose not to disturb her. There's no need; where there is an incubating female, the male is sure to be close by. The male usually hangs out in the dead trees that are anywhere from 10-30 feet away from his nest. The best time to photograph this particular male is in the morning. I arrived on this day late in the 2 o'clock hour, which ensured that the Osprey would be side lit. With the branches of the tree blocking some of that sun, it afforded me few keepers.
I would recommend 560mm - 700mm for photographing the rest of the Osprey in the area. In the late afternoon, they will be frontlit and sitting in the trees on the opposite side of the road.
All shots were taken with a Canon 50D in bad need of a sensor cleaning and a 400 5.6L lens. The final shot is not cropped.