This image was taken during my wild mustang IPt last June. The bands of wild mustangs usually go to water twice a day. Here it's later afternoon and they came in a hurry. The lighting emphasized the dust they were creating. This is a cropped from a single image.
Robert,
The dust adds a lot to this image, as pointed out. I would suggest that the upper right hand corner is a little distracting (the patch of sky that appears), and that the right side of the image is cropped a little too tight to the right-most mustang.
Having more of them catch the sidelight would have been even better. :)
I look at this in the morning but was at work and tied up so just getting back to it now. I would agree with David. I had same thoughts on the sky and right hand crop. Didn't consider the light though.
The dust cloud definitely adds a great sense of action to these image. Agree with the suggestions by David and Robert, might even consider cropping out the last group of four altogether to provide a little room at the frame's edge.