The beauty of a well executed dusk shot is to feel the juxtaposition of the warm lights of the interior with the blue cast of the building facade and midnight blue sky. Dusk shots can be a challenge for a number of reasons: the direction the building faces will dictate whether it should be shot at dawn or dusk, the balance of interior light to the building color and density, the short window of time to execute the shotof and the technique used to record the imagery all play into the success or management of the final file.

I like to see a nice deep blue for the sky color, (sometimes needing a gradation tool in photoshop), a facade that has tone and detail yet shows the effect of dusk coming on,
and interior lights that hold their tone and color to a beautiful warm level.

All of this means having to shoot multiple exposures and densities as the light descends and the night sky becomes a deeper blue, typically over a period of 20-25 minutes during the period at dawn or dusk known as the "Blue Hour". A tripod is a necessity as well as a device called an intervalometer which hits the shutter automatically and in regular timed intervals. At the end of the 20 minute session, I may have 350-500 images all of varying densities. I will select about 5-6 images to work with in Photoshop using layers and blending techniques to bring the shot together in one believable studied shot. Here are some examples from the Summit Avenue book.