Hey Dale,
Really nice shadow play on the dunes and that is one killer rainbow!!! Now don't all jump down my throat....but I prefer the image with 1/4 of the sky cut off the top.....even at the expense of the rainbow.....just because it emphasizes the dunes more.......still really, really like it as presented.
Dale,
Great light and a fabulous Rainbow...I like the two different gray tonalities in the sky...I could go either way with the suggested crop...but really like the original as posted.
Did you use a split ND filter on this?