Time lapse and narrow shutter angle
Posted 24 December 2006 - 04:27 AM
When doing time lapse, one minute intervals seem to work best for me when i want to reveal the movement of shadows. If I reduce the shutter angle so it is about a quarter open while doing one minute intervals, would the movement of shadows appear as smooth as if the shutter angle was fully open?
Posted 24 December 2006 - 05:37 PM
If you are using a rotating shutter on a camera not set up for time-lapse then there will be 2 periods per frame when the shutter is half exposing the frame, if anything in your exposure were to flare up in terms of light intensity during these times then the shutter will cast a shadow...
Either you need to shoot constantly lit subjects or modify your shutter/drive system so that it whips the shutter around in these transitional periods and you can then enter the mark/space times (expose/not-expose times - which added = your fps) as opposed to just the fps (and whatever shutter angle is directly slaved from this) ...
hope this makes sense
Edited by Nick Mulder, 24 December 2006 - 05:40 PM.
Posted 25 December 2006 - 01:19 AM
The frame rate of any given subject is something so variable it?s often learned via trail and error. Experiment with both shutter speed and frame rate if you like ? but with today?s inexpensive computerized post tools like Final Cut you can ramp away to your hearts content. Because of this it always better to have more frames to ramp/play with.
Posted 25 December 2006 - 08:41 AM
Posted 25 December 2006 - 03:55 PM
My only suggestion to try to get a smoother picture (keeping shutter angle as high as you can) is to maybe pull process the film a stop or two, I dont know the effects on that stock but generally I think its near the opposite of pushing - lower contrast and therefore maybe more shadow detail ...
Posted 26 December 2006 - 02:18 AM
I would prefer to use the usual slow shutter speed for these time lapse shoots but I am using 100D in bright sunlight. I'll be forced to narrow the shutter angle when I do the time lapse.
Won't increasing the shutter speed essentially ruin your test by introducing an unwanted variable into the look of the footage, given that you say you prefer a slower shutter speed anyway? If so, then ND is the way to go.
If you can't get a suitable glass filter in time, then one (admittedly ghetto) option is take a gel sample pack, cut out ND's in the shape of your lens's rear element, and attach them with snot tape. This is assuming you don't have a camera that can take filters behind the lens like the Bolex. Just remember to stop down to T8 or so, as the thickness of the gel will shift your focus slightly.
I wouldn't consider pulling the film, since this would throw another unwanted variable into the footage and cost you more money.