Went back and reshot the towers to see if I can capture that deep blue sky during dusk. I was remotely pressing the shutter (using a Canon RS-60E3 China-made substitute) once every half minute or so (because I was waiting for the lights to turn into a combo I like). Although to my eyes the sky didn't seem to be changing much in color, as you can see here it was all over the place! And to think these shots were taken within less than two minutes. All images: 1", f/10, ISO 200, EF 75-300 III @180mm.