Zoom blur or ICM can be created by zooming in or out on the subject on a long exposure. This creates nice streaks and if your subject is lights, then you could create really attractive light trails.
Another thing to remember is that if you want to first get a good exposure on the subject before you zoom, you need to trip the shutter and let it expose for 1 or 2 seconds (i.e. don't touch the lens yet), before you get into the zoom. If you want to also mark the end of the zoom, you will need to again do the same thing of exposing the subject for another second or so at the end of the zoom (i.e. don't zoom in/out anymore). A mid-point exposure could also create an interesting image, and the whole idea is to play around with different exposure settings and zoom speeds while doing this.
It's a fun exercise, and you must try it sometime - no 2 images come out the same!
What you need:
- Tripod
- Camera with a zoom lens (the longer the zoom the better)
- Subject you want to zoom (lights are really interesting - I used tea light holders)
- Cable/remote release (optional)
What to do:
- Place your camera on the tripod and set up your subject in a way that there's ample room in the frame around the subject. It's a good idea to place the subject in the centre.
- Set an adequately low ISO as you will be using a long exposure and choose an appropriate White Balance if you're going to shoot in JPEG (you can leave this on AWB as well).
- Set a slow shutter speed - anything slower than about 2 seconds; this will ensure that you have enough time to zoom your lens. Of course, try other shutter speeds as well, just for fun!
- Choose a moderately large depth of field if you would like the zoom to be sharp. Otherwise, choose a desired f/stop for the kind of shot you want.
- Now you are ready! Trip the shutter and being careful not to shake the camera or the tripod, zoom your lens in or out.
- Way to go - you've got a really cool shot!
Here are a few samples from my experiment. I was using my 55 - 250 mm lens for this.
Zoomed out to 55 mm, f/13.0, 4s, ISO 100, AWB
I tripped the shutter, waited a second or so, and then zoomed in half-way fairly rapidly .
Zoomed out to 55 mm, f/13.0, 6s, ISO 100, AWB
I tripped the shutter, waited a second or so, and then zoomed in half-way quite slowly, causing the softer blur.
Zoomed out to 55 mm, f/13.0, 6s, ISO 100, AWB
I tripped the shutter, waited a second or so, zoomed in quite slowly, and let the subject expose for a second at the end as well. This created the definition in the pattern of the tea light holders in the zoomed in position.
Let your imagination take over, but have fun in the process!