Long Exposures in Conjunction with Focal Length Shift

Hotel Del Coronado

Coronado, CA, United States

Canon 5D Mark II

Focal Length 100 - 67 (varied)

Aperture 22

Shutter 20 sec.

ISO 800

For those of you who are wondering how this was done, it's pretty simple.  You'll need a tripod, which you'll need for virtually all low light, and night photography.  The reason is when you shoot a photo a shutter is allowed to open.  Think of a shutter like a window.  To allow the camera to take in light you'll need to open that "window" for a certain amount of time that is dictated by the current ambient light. The less ambient light that there is (the darker your subject is) the longer you will need to leave the shutter open to properly expose the film.  In this case, since there was so little light I had to leave the shutter open for and extended period - 20 seconds.  During this time it is absolutely essential that you keep the camera completely still, as anything that is moving during the exposure will come out as motion blur.  Typically this is something that is undesirable.

For this shot I used a few techniques.  One was to place the camera on a tripod to limit the amount of motion blur that I had on the parts of the image (the hotel's frame), while simultaneously changing the focal length.  Since night photography most clearly records the parts of the scene that are lit the lights create a streaking effect when the focus is altered mid shot.  The reason for using the tripod is to avoid any vertical or horizontal sway of the hotel, which would give an undesirable messy look.

By looking closely at the photo you can see two hotels - a smaller one within a larger one.  The focal length was at 67 when I initially opened the shutter, and over the next 10 seconds I gradually adjusted the focal length to around 100.  When the focal length was at 67 it was capturing the smaller hotel within the picture because less zoom was being used, but as I shifted the focal length throughout the shot I stopped at 100 that captured the larger hotel.  The larger number for the focal length, the more “zoom” you are using.  One other important note on manually adjusting the focus during an exposure is to keep the movement fluid, if this is done in a jerky manner certain parts of the transitioning streaks may be brighter than others or appear to be segmented.

One potential problem to this however can be to retain the proper focus throughout the shot.  Fortunately for most nighttime landscape shots your focus will be set to the infinity symbol (∞) or somewhere near this.  When the focus ring is set to infinity everything within the frame should be in focus.

Another trick that I like to use during night photography is to use a smaller aperture (higher F stop number, in this case 22).  The aperture works in conjunction with the shutter and also deals with the amount of light that is coming in and determines how long this light must enter the camera.  Think of the shutter as the size of the window.  The larger the window (smaller F stop or aperture) the more light will come in, resulting in a faster shutter speed that is needed to properly expose the photo.  Just remember, since the window is bigger, and lets in more light you don't have to leave it open as long.

In this case I used a very small aperture (F 22) so that I would get a pleasant starburst pattern surrounding the lights.  If a smaller F stop, such as 5.6 were used the lights would more resemble the shape of a globe or an orb and they would be less defined.