South Prairie Creek Time Exposures

Using long exposures to smooth out the water surface

I used some neutral density filters to allow me to take longer exposures of moving water. The image above is taken from the bridge over South Prairie Creek on the bike/hike trail through town.

I say ‘town’ advisedly, because there are maybe 25 homes total in S Prairie.

This image has a lot of depth to it, which was partly due to the high-quality lens used (32mm Rodenstock Digaron HR), and partly due to bringing out the right shadows in processing. As usual, the medium format chip captured more light than I needed so I could tweak the light balance.

The image is a vertical panorama, consisting of five shots that overlap quite a bit. I used vertical rise and fall to get views above and below the center view. The 32 mm lens has an image circle (the illuminated area at the sensor plane) of 90mm, so I used movements on the back of the Cambo camera to record images in those extended areas.

The 32mm lens was so wide that I had to lean the tripod against the side of the walkway in order to not have the walkway wall obstruct most of the image. Only much later did I remember that I have a central column that I could have used to raise the camera position. :)

Below is what I’m looking at when I set up the shot. The time exposure was 40 seconds; aperture was set to f/16, and ISO was at 50. (The photo shows the screen for setting exposure settings; I can also get a live view of what’s coming through the lens.)

Earlier, I had also taken a time exposure through a more dense neutral density filter. The shot above was a 10-stop ND filter, which was what allowed me to shoot a 40s exposure at f/16 on a sunny day. (One would normally expect to shoot at f/16 and 1/50th of a second.) 10 stops would have normally taken me to 15-20 seconds, but I have good recovery with this sensor so I added one extra stop to the exposure.

This photo was shot with a Mamiya 45mm lens with a 16-stop ND filter, so I had to use 2 and 4 minutes for useful exposures. Here is the 4-minute exposure. There doesn’t appear to be much in the way of moving water in this photo, but there was actually a lot visible. There were wind ripples all over the foreground water, for example; the super-long exposure smoothed that out and allows us to see the rocks in the creak bed.

As in the first shot, the foliage moved more and less at various places. I figure there’s no way to control that if there is even a mild wind present.

These were just tightly controlled tests with various filters and exposure times. I will start adding these to my water shots soon.