photography: motion blur and flash
Posted 16 February 2006 - 09:35 AM
i am experimenting with applying some photograhpy techniques to film. one of these technniques is when a subject in a photograph is sharp but also has a motion blur tail behind it (i think it has been used to some nike adds). I think that this is achieved by using a long exposre and a flash towards the end of this exposure. For exapmple a half of a second exposure and a tenth of a second flash.
Now I am wondering whether this can be applied to film and the moving image as well. I already tried to get motion blur by slowing down the camera and getting a TK done at the same speed (f.e. 8 fps and scan at 8 fps). For example: there is a person running through the frame in motion blur. that was easy to achieve but now I want the movement to become sharp and not blurred for while in the middle. I was thinking about different options. maybe using a flash that is in and out of synch with the shutter of the camera? Or maybe just cranking the camera speed up and down quickly? My brain starts flipping .... anybody any ideas? I guess I have to do some test, or better a lot of tests ....
Posted 16 February 2006 - 09:44 AM
you could try using a high-speed strobe (disco strobe, not photo flash) and low shutter speed, but you wont get a very long trail.
Posted 16 February 2006 - 12:38 PM
Seems like a spot meter would help in this situation.
Posted 16 February 2006 - 12:59 PM
One advantage to shooting digitally is at least you can double the amount of blur by switching off the shutter, so you wouldn't have to undercrank as much for the same affect. You could shoot at 12 fps and get a 1/12th of a second exposure time per frame, as opposed to have to shoot at 6 fps with a film camera to get 1/12th, since it would have a 180 degree shutter.
Posted 18 February 2006 - 12:41 AM
Posted 18 February 2006 - 12:46 AM
If the strobe(s) was the only source of illumination, could you somehow remove the shutter from the film camera? Also - how would you synchronise a strobe to a camera - or at least make it fire exactly every 1/24th of a second?
Well, you could remove the shutter as long as the strobe only fired while the film was static in the gate, not advancing to the next frame -- so you might as well leave in the shutter. You don't really get more usable exposure per frame by removing the shutter since it needs part of the time to move to the next frame.
In terms of syncing strobes to the shutter, there are sync boxes for that but honestly, I've never done strobe photography, only fired strobes randomly (not in sync) during scenes (for nightclub scenes, gunfire scenes, etc.)