* Nikon D7000: Tripod at 30.0 sec @ f/22, ISO 100, Aperture Priority
Whether your a morning person or and evening person, you are in luck because there are two "blue hours" every day, but I should note that this period of time is rarely an hour. Blue hour is a period of twilight that occurs each morning and each evening when there is neither full daylight nor complete darkness. For a photographer who wants to capture the deep, dark cobalt/navy blue of blue hour, you will have to be up in the dark early morning hours, way before sunrise, or you must stay out into the darkness of post-sunset evenings, when your instincts tell you it's way too dark to get anything worthwhile. Those are the moments when your camera sees that which your naked eye cannot - the first or last remnants of light creating a deep blue background to every photograph.
Nikon D90: No tripod at 0.6 sec @ f/4.5, ISO 500, Aperture Priority
The challenge in these hours is focusing, so it's recommended that you focus from your shooting vantage point when there is sufficient light, and make a note of those settings. Exposures in this kind of light will be long, so you must have a tripod, and to avoid shaking the camera while taking the picture use either a remote control or the timer setting. Whatever you do, pack your patience because I promise you will be rewarded. Images with landscapes or cityscapes with man-made lights and skylines yield spectacular results. Being a lover of the color blue, I must say these are blues unlike any others I've seen and are well worth the small efforts to obtain them.
* I was surprised by the evening in Zurich, the stillness of the waters, the reflection of the city and that blue hour. Having no tripod, I steadied myself against a cement wall and raised the ISO only to a point where I knew the D90 wouldn't give me irreparable noise. Given that I didn't have a tripod, I had to take what I could get. At an aperture of f/4.5, the camera gave me a shutter speed of 0.6 second and the least depth of field. If I asked for more depth, the shutter would have to stay open longer and I knew I'd be more susceptible to camera shake, so I took what I could get and tried my very best to focus on the bridge. I think it worked, what do you think?