Wednesday, February 10, 2010

Time Exposures

These shots had been rattling around on my idea list for a while. WSCF had a meetup last weekend at an office in Carol Stream and I convinced the folks to help me with these shots. Thanks, you guys!

The idea is to take longish, "time exposures" to get interesting blurred subjects. When you're taking shots of a couple of seconds, you have to set a pretty high f/stop to compensate. You're hitting the sensor with light from the image for a long time. So you have to reduce the volume of light by "stopping down" the aperture to a higher f/stop.

Scott and I decided to try an exposure of 10 seconds at f22.


As you can see, the effect is pretty disappointing. My vision was that you would actually be able to tell someone had walked by. In this shot, if you weren't looking for it, you might think it's a hallway with a shadow on the wall.


So we adjusted the exposure 2 seconds at f16.

"Have you seen the network guy?"  "Uh, I thought he was just over...where IS he?

That's the ticket. Now you can see Scott, and he's nicely blurred and ghostly. Technically, we reduced the time that the sensor sees the image, but we've increased the volume of light hitting the image. So Scott becomes visible.

So after the testing was successful, we went with the shot I had envisioned...

I love it when a plan comes together.

One thing that should be obvious, but I'll mention it anyway. Ya gotta use a tripod and, preferably, a remote shutter release as well.

Jim Frazier

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