This is the martial eagle, one of Africa's largest eagles* and a truly formidable predator, even occassionally killing small antelope like duiker. This adult was a fair distance away but the presence of large nests gives away the location of trees where they might be found perching.
* I say "one of" because books differ as to whether the title belongs to the martial or the similarly sized crowned eagle. A comparison of various field guides suggested that the crowned is longer but the martial wins in terms of weight and wingspan (which has an impressive maximum of 8.5 feet).
Very nice photo.
I think it is like polar vs. brown bears. The largest of them all is a polar bear (or two) that are way bigger than any brown bear. But if you randomly pick a polar bear and a brown bear, the brown bear is almost always going to be bigger.
I've seen plenty of both, with the martial's being mostly So. African and the Crowned being all in the Congo or Tanzania. My impression is that the largest eagle I've ever seen in my life was a particular crowned eagle that was feeding on a troop of monkeys in Zaire, but the Martial eagles typically have this whopping huge wingspan.