I had done this shot several times before, but mostly in the summer time. I wanted to do it again in the late autumn or winter when the sunset is much earlier and the office lights in the buildings are still lit. Last night I was able to photograph between 4:30 and 5:00pm, perfect timing for the city lights.
The next part of the shot involved the streaking lights from passing vehicles, and in the 4:30-5:00pm envelope there was plenty of mid-week traffic to accomplish that.
The Flatiron Building is not lit at night, which means its details go dark very quickly after sunset. If you wait too long to photograph it, it becomes a black tombstone. There needs to be a perfect balance in capturing the detail and outline of the building and the traffic lights in the same exposure. The best shot of the building balanced with the traffic lights turned out to be a half hour after sunset.
I positioned myself on a divider in the road so I could capture the lights of passing traffic from both the left and right. Of course the traffic itself never fully cooperates, and it was necessary to combine the traffic patterns of four images to create the results I wanted.
For this image I used the Nikon D810 for its exceptionally high resolution, which will allow me to maximize the size when making prints. The lens was the Nikon 24-70mm f/2.8 zoom set to 35mm and f/6.3 for a 4 second exposure. At an ISO of 64 the detail with the D810 the detail is amazing.