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.
|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.|