You can see some of that effect in these iPhone pictures. http://blog.flickr.net/en/2010/08/24/rolling-rolling-rolling-shutter/
On Fri, Dec 24, 2010 at 8:49 AM, Doug Franklin <[email protected]> wrote: > On 2010-12-23 23:38, Paul Ewins wrote: >> >> [...] During the 1/250 sec each spoke travel a little >> bit further than the distance to the next spoke. This means >> there are sections where it has doubled up (i.e. both the >> current and previous spoke have occupied that position during >> the exposure) so you get the "ghost" spokes as well as the >> uniform blur. > > I think you've got it, Paul. That certainly explains the situations where > I've encountered it. And it is a sort of a "temporal moire" pattern thing, > which I'm pretty sure is the underlying cause in some form. > > Larry, it doesn't seem so much tied to a particular part of the track as it > seems to be tied to some larger set of circumstances. I've seen it at > different parts of the track on the same and different cars with the same > and different sorts of wheels. > > If I extrapolate Paul's thinking, it's tied to the combination of the wheel > speed, shutter speed, and the specific wheel design (spoke pattern). That > seems reasonable based on where and when I've seen it happen. > > The panning does other weird things to wheel spokes. I've got dozens of > shots where the spokes at the top or bottom of the wheel look straight while > the ones at the bottom or top look highly curved. The moving shutter slit > could affect these, too. > > I'm sure the moving shutter slit does cause some "length telescoping", but I > haven't had any racing shots where it was particularly obvious to me. > > -- > Thanks, > DougF (KG4LMZ) > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions. > -- David Parsons Photography http://www.davidparsonsphoto.com Aloha Photographer Photoblog http://alohaphotog.blogspot.com/ -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
