One way to make a photograph more interesting is for it to be different from other pictures in some way. A couple of days ago, I was walking on Lake Street across I-94 in Chicago. My idea was that a longer exposure might make this image a little different than the norm. By using a longer exposure, the moving vehicles blur while the surrounding landscape remains in sharp focus.

It's easy to dial in a slow shutter speed to create a long exposure at night. It's more challenging during the day. In the bright conditions, even the narrowest aperture and lowest ISO setting results in a shutter speed that's too fast to create the blur.

I used the following steps to blur the traffic:

• Used a very narrow aperture (f/20). This minimizes the amount of light that reaches the sensor.
• Set the base ISO of 100 to minimize the sensor's sensitivity to light.
• Attached a neutral density (ND) filter to my lens. This reduced the amount of light reaching the sensor by about 7 stops.

The resulting shutter speed was nearly a full second (0.8 seconds)...slow enough to create the blur. For more blur, I would extend the shutter speed to taste. This would be accomplished by using a stronger neutral density filter. Or in the case of my Vari-ND filter, I simply rotate to filter to strengthen the effect (anywhere from 1 to 8 stops). I also have a 10 stop ND filter.

Another factor in the equation is the speed of the traffic! When the traffic is inching along, it takes a far longer shutter speed to create blur. If the cars are speeding along at 60 miles per hour, a much faster shutter speed will still blur the vehicles. Fortunately, the LCD screen on the back of the digital camera provides instant feedback so shutter speed adjustments can be made instantly.

The key to creating a photograph like this is the ND filter. Without it, it's not possible to set the camera for a long enough shutter speed without overexposing the image.

Interstate 94I-94 overpass at Lake Street in Chicago, Illinois on July 6, 2015