Never leave your creativity at home
For the blurred images I often like to take, I need a ND filter *) to block out some light. Even with ISO 100, f-stop 11-22 and a shutter speed of around 1 second, I get way to much light on my sensor. So I need a ND filter to help me out. Mostly I use a adjustable circular one, which has the advantage easily opening up the filter as to see enough to get the scene into focus and then closing the ND filter again to the desired reduction.
So what to do when you have left the ND filter at home? Drive back home to get it, wait until the light is going or do an experiment.
I hardly ever let the opportunity pass for an experiment, so I started thinking how I could block out light during the exposure time. What if I could block the light out partially? But I would have to move the blocker, otherwise a part of the exposure would not get light at all. So I started by putting my camera in the tripod and slowly moved 3 fingers before the lens during exposure. It seemed to work in its primitive way. I then made a slit with 2 hands and then I cut a slit into a piece of paper I had with me. That way I could move the camera during the exposure and reduce the amount of light by moving the slit in front of the lens, only letting in light through the slit in the paper.
A new animal had awoken
Where I had started to mimic the ND filter that was faithfully waiting for me at home, I found out, when sorting the photos I had made that day, on my computer that a new kind of images have emerged. The combination of moving the camera en moving the slit created a new thing. I was fascinated and started to build a device which would make it a bit more stable and easier to handle. And gives me more control.
The image above is one of the 'Slit' photos
*) A 'ND' filter is a Neutral Density filter, also called 'grey' filter, which reduces the amount of light in a neutral way by 1 or more f-stops. Now 'neutral' seems to be rather relative, as most Grey filters cause a color shift. E.g. the very expensive Lee ND filters cause a huge color shift towards yellow. But Lee is not alone.