What settings do I need to take a night cityscape like this?

Question

I was wowed when I looked at this image on google maps for the Prudential Tower observatory. Then I start digging into the photographer (Eric Rolph -flickr) and I found he had some stunning pics beside this.

What do I need to take a picture like this? Stand, long exposure, how much if yes? Can I achive something similar with my Nikon D5100?

For reference this photo was taken with Canon EOS 5D

Answer

You can very well take night shots like this with D5100. I'll explain from my experience when i took this pic.

Time

Timing is very important in city-light shots. You can see the deep-blue/purple color of sky in the example picture you posted. You get this color a bit after sunset (Twilight). Unlike other landscape shots, you need a clear sky. So plan your trip to the observatory accordingly.

Lens

A wide angle lens is the most suitable for city-light shots. Apart from getting a wide viewing angle you also get a good depth of field.

Aperture

What you need is a large depth of field. Setting it more than f/8 on a wide angle lens gives you good depth of field. Few city-light shots look particularly good if you go all the way to f/22. You get star burst from light. But this depends on your lens.

Shutter speed

I exposed my light meter off the blue sky. It gave me some 10s of shutter speed. Generally it is a good idea to meter off the blue sky.

Tripod

You definitely need a tripod or a solid support for your camera. Exposure time is going to be much more than you can hand hold the camera.

Other consideration

1. Observatories have big glass windows. And at night they start reflecting room lighting. Be ready to post-process them out.
2. Shoot raw. You might want to change WB later.
3. Use lens hood.

Check more discussion of this question.