Years ago, my wife gave me a copy of John Shaw's first book on Wildlife photography. In it, he advised getting prime lenses in multiples...24mm, 50 mm, 105 mm, and so on. Of course, zooms were not held in really high esteem among Professionals back then. (Not sharp, you know!) I've got a 50mm f/1.8, and a 100 mm f/2.8, which give an equivalent angle of view on my D 7100 of 75mm and 150 mm, respectively. I'm thinking that the 24mm f/2.8, FX, with an equivalent of 36mm would be a good thing to fill in, realizing I have zooms, a 24-85 f/3.5-4.5, and an 18-140 3.5-4.5, both very sharp. Bumping my ISO to 800 would more than eliminate the difference, without a noticeable increase in noise. Any counsel you can give? Thanks!