This is a small crop from a larger image. ISO 1600 does produce noisier images and is accentuated when USM is applied. Still, it allows the shot to be taken and either NeatImage or Noise Ninja will clean it up a bit (did not use either in this image). Aperture-Priority, f/8, 1/40, ISO 1600, EC +1/3. Canon 75-300 IS lens at 300mm.