Wednesday, May 18, 2011

Photographing cities at night

The moment of perfect harmony:

The modern DSLR has made night photography easier than ever.  There are a few tricks you need to know to improve your photos beyond the ordinary.  First of all, let's discuss the equipment you will need.

A tripod or some sort of steadying device is mandatory.  Night exposures are long and camera blur will occur if the camera is not rock steady.  A cable release, while not necessary, is helpful for keeping your images blur-free.  The simple act of touching the camera to press the shutter button is enough to add some motion blur to the shot.  That said, I will also discuss some alternative work around for dealing with situations where you do not have a cable release or tripod.

Timing is the most important aesthetic element in taking night photos.  Photographs look better when there is some detail and color in the sky.  The ideal time to take your night shots is 10 to 20 minutes after actual sunset.  I call this time slot the "moment of perfect harmony" where the exposure for the sky is perfectly balanced with the exposure of the city lights. At this moment you will be able to record some detail in the sky, which often goes a bluish color.  Don't be afraid of taking night photos on cloudy days.  The sky will still turn into a nice deep blue background.  This is due to reciprocity failure, a topic I will cover in a later post.

Photographing into the west 10-20 minutes after the sun has set can add nice color and detail to the sky.  Notice how the lights of the city and the light in the sky are perfectly balanced.  In this case, proper timing of the shot gave plenty of detail everywhere with no heavy black areas. The exposure was f/5.6 at 4 seconds.
 
Here the photo of Washington DC was taken facing east so the setting sun was behind me.  The sky had no color or detail that was visible to the eye.  Nonetheless the camera recorded a very pleasing overall blue balanced against the lights of the Capital Building. Both situations had water foregrounds to reflect and amplify the colors of the scene. This also avoided a foreground that might have gone dead black.  Exposure of f/4 at 1/2 second.






Proper exposure is very easy with modern DLSR cameras.  For the most part, I find it easiest to put the camera in its "A" for "Aperture Priority" setting.  This allows you to select the lens aperture you want and have the camera choose the shutter speed.  While almost any aperture will do, f/5.6 or f/8 is often the most optimum optical setting for a lens.  You can check your results on the camera display and by looking at the histogram to see if it is balanced. You want the high parts of the histogram graph to be in the middle.  But be careful because your histogram can be skewed to one side or the other if there are large dark areas of very bright lights in the scene.  Best bet is to bracket your shot.  Do this by setting your camera to over expose by plus one stop and under expose by minus one full stop.  You can set most DSLR cameras to do this automatically for you, but that might be more trouble than it's worth for the few exposures you are going to take of a scene such as this.  My preference is to use the over/under (+/-) exposure button and dial on your camera.  With your camera still on the "A" setting, change the +/- setting to +1.  Take a photo. Change it again to -1 and take another photo. That should do it, but you could play safe and go for a +2 and -2 also.  You should be shooting in RAW because this will provide the most options for adjusting the exposure afterwards.  The JPG format will be too limiting if you do need to make exposure corrections on the image later on in post processing.

For this scene of the El Morro Castle in Old San Juan, Puerto Rico, I took the same photo several times over the 10-20 minute time frame.  My camera was pointing north.  The sun had just set to the left so the sky was brighter on that side.  In addition the lights on the castle were very dim and I wanted to be certain the exposure was perfectly balanced in both the sky and on the castle.  Later I had to dodge some of the light off the right side of the photo to bring it into further balance with the left.  To complicate matters even more, this photo was done in two shots that were later put together to make a panoramic image.  A steady tripod is absolutely essential for a shot like this done at a 1/2 second exposure.




Working without a tripod or cable release:

There are times when you do not have a tripod or cable release with you.  To steady the camera you will need to find a firm place to rest it.  Then you can prop something under the lens to gain elevation and angle it in the right direction.  I usually use my wallet or keys.  You can use the camera's self-timer feature instead of a cable release.  I usually set the time for a delay of 2 seconds.  Press the shutter and remove your hand from the camera and 2 seconds later it will take the exposure.  For extreme steadiness I often use a feature most DSLR cameras have to lock up the mirror.  When the mirror slaps up and down it causes a vibration that can blur your shot, particularly if you are using one of these emergency techniques for propping up the camera. That is the method I used to take the photo of the Coliseum below.

By the time I took this photo of the Coliseum in Rome the sky was already past its prime in the light envelope and came in dark.  To offset this I did a time exposure that included the light streaks from moving autos in the foreground.  The camera angle was very low.  In fact I placed the camera directly on the sidewalk and propped my wallet under the lens to angle it up.  In this case I used the camera in Manual mode and read the exposure for the scene without the car lights.  I wanted to keep the shutter open long enough to blur the lights of passing cars as streaks in the scene.  The exposure was f/8 at 5 seconds. I waited until I saw a large group of cars coming by and opened the shutter.  It took several tries to get it right, but the lights added interest to an otherwise dull foreground.
This scene of the Flatiron Building in New York was taken 10 minutes after sunset facing south.  There is still plenty of light in the sky.  An exposure of f/4 at 3 seconds was enough to record the passing cars as blurred lights.

The important thing to remember is that you want your pictures to have plenty of detail.  Try to avoid dead spaces of deep black.  Choosing the right time of day to shoot is critical, but proper placement of elements is just as important.
This dusk shot of the arch in Washington Square framing the Empire State building in New York is the result of carefully balancing the time of night with the artificial lights in the scene.  Photographed facing north the sky is a deep blue.  Any later and it would have been totally black and the shot would not be as interesting.  Adding to the interest is the light post on the right.  All of this is a result of achieving a perfect lighting harmony in the scene.

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