I was just sitting around the house bored today and decided to try something I’ve seen but never attempted – the long-exposure zoom. I didn’t have any specific subject in mind, but outdoors was out of the question because of wind (the edge of Hurricane Isaac is creeping up on us even here in Iowa). I pointed the camera at several different objects around the living room but this brass vase came out the best I think.
When you are manually cranking the lens during the exposure to create the zoom motion blur, you’re not going to get a super sharp image no matter what preparation you do. Obviously a tripod is a must, and I found I got the best results using a remote shutter control and pressing down on the camera and tripod slightly with the hand on the zoom ring. Pushing seemed to add a little more stability (because I have a beginner-grade tripod). Also, using this technique, make sure that one leg of the tripod is pointing forward, in line with the lens, to add extra stability (otherwise the tripod might tip forward as you push down on the camera lens).
I also found that it helped to twist the zoom lens a few times before the shot to loosen it up a little and get the feel for how to turn it with the least vibration possible. I used my standard kit 18-55mm for this shot, and the relative low quality of the lens meant that the zoom ring tended to stick slightly, which added visibly to the vibrations.
I played around with different shutter speed lengths, from one second all the way up to 20. I found that, for me, two seconds was the sweet spot that got me the biggest impact. I could take my time adjusting the zoom which meant I could do it more smoothly. It also makes a great deal of difference how much you zoom. Too little and it just looks like the camera was shaking. Too much and you either end up with a blob or a well-defined image at one zoom level and a ghost of the image at the extreme other end.
A lot to keep in mind, but I kind of got the hang of it in only about a dozen shots. Doubtless I could google a means of achieving the same effect in Photoshop, but that’s cheating. :)