For this second trial at rotational camera movement I tried moving the camera during a long exposure. I hadn’t tried this before as I didn’t have a strong enough neutral density filter to get the long exposure.
I overcame this problem by using 2 circular polarising filters back to back (or front to front) and rotating them relative to each other to get a strong enough effect. Trying this out didn’t work at first and it was only by trying different combinations that I hit on something that worked. It was only afterwards that I did some research and now understand what is going on. In the setup photos you may be able to see the Blue Tack holding the front polariser on.
What I am showing below is first the static view, then a number of attempts that give different impressions – this is not the whole set: some didn’t work well enough and others where too similar. I indicate the exposure times for each rotational view. The view I used is of a tree across a field of rapeseed at the back of our garden.
What was interesting is how the effect changes with the speed of rotation, the duration, and the amount of rotation. Although I took care in aligning the setup on the trunk of the tree, on some images the centre of rotation has moved – care is needed!