While it may be an artless art, it's not a skilless craft.
First requirement is a low enough light level to slow shutter speed down to between 1 and about 10 seconds, so you're either going to need to work indoors, choose a time of day when light levels are low or fit a 10 stop filter and close the aperture of your lens untile the blades squeek. This evening was overcast with a little bright sun filtering through the clouds to provide some catch-lights and give 1.5 to 3 seconds at f22 with a sensitivity for the camera of 100ASA.
Next comes lens selection. I wanted to get in close and really be near the subjects, so I used a Sigma 20-35 zoom, most of the time around 20mm, though a 24mm or equivalent lens could work similarly. Being close with a wideangle distorted perspective, smearing objects further away across the edges of the frame and exaggerating camera movement there. This also allows light objects to leave light trails if the camera is pushed towards them in a way that couldn't happen with a longer focal length.
Finally comes the type of movement. The obvious ones are:
Rotation, where the camera is turned during exposure.
Agitation in one plain where the camera is moved up & down/side to side.
Zooming where either a zoom lens is zoomed while exposing or the camera is moved toward or away from the subject as I did.
It can also be beneficial, depending on how much residual information is desired in the image, to keep the camera still for part of the time before commencing movement.
As for processing, forget about sharpness and straightening verticals. Key things are framing, tones and colours. Framing may need adjustment, simply because once the shutter closes there's nothing to see through the view finder, and it's hard to predict exactly what the camera will take in or how far off-centre you've drifted while moving. Tones and colours because, with a blurred subject, they are the means through which you control the appearance of the image.
These are the first ICM images that I've published, though certainly not the first I've shot. So do the results justify the means? Comments welcome.
Natural fairy lights.
OK, so I've named the images - pretentious after all. Somehow it seems to help them make sense a little more.