Fifty mm lenses are useful for many subjects and one of the great uses for tilt-shift lenses is architecture.
From a previous Philadelphia visit, I knew where this focal length would work well with plenty of architecture in the frame.
The procedure for capturing this image is a rather standard one for me. Scout the location (already had this step done). Show up before sunset with a pair of cameras, lenses and tripods. Set up both using two significantly different focal lengths (cropping can effectively handle smaller differences in focal length, especially when using a 5Ds or 5Ds R camera) and begin photographing the city using a level-on-both-axes camera and a sharp f/8 aperture as the sun sets.
When the lights come on, I adjust the aperture to f/16 to gain the starburst effects from the lights. This aperture is not as sharp as f/8 due to the effects of diffraction, but details remain sharp enough (ideal would be to merge the areas of an f/8 image with the star effects of an f/16 image). Also, soon after the lights come on, I begin capturing an underexposed frame periodically so that I could later use it to pull the brightness of some of the lights down (the gridded triangle roof top was especially bright). I adjust the exposure as necessary as the sky darkens and when there is nearly no color left in the sky, I usually pack up and head home.
In the end, I usually archive most of the earlier-captured images as the images captured within the ideal 5 minutes of the blue hour are usually my most-preferred. Usually, the perfect timing exposure is f/16 for 30 seconds at ISO 100.
A larger version of this image is available on Flickr.