Film-Tech Forum ARCHIVE: Half- keystoning!?!?

This is topic Half- keystoning!?!? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by David Yauch (Member # 2754) on 11-04-2004, 03:00 AM:

So I go to start a theatre today. I double check the film path, the framing, the sound, the lighting, and start it up. Everything looks pretty good until I notice that the picture looks like it's keystoning very badly when I look at the right side, but when I look at the left it's perfectly parallel to the wall throughout the shot. I checked the aperature plate, lens turret, and the film path again but nothing was out of the ordinary. It became less noticable as soon as the movie started and filled the whole screen, but no one seemed to know what caused it. Anyone have any ideas?

Posted by Carl Martin (Member # 1146) on 11-04-2004, 03:07 AM:

scope film, right? the lens's azimuth is off (it's rotated a bit).

carl

Posted by Brad Miller (Member # 2) on 11-04-2004, 05:01 AM:

You probably have stadium seating, a curved screen, or at least you are referring to an auditorium where the projector is pointed downward a reasonable amount. As posted above, if the scope lens is slightly crooked in the turret, one side will appear parallel to the masking while the other will look horribly crooked. Once you rotate the lens slightly you will see that in face you have keystoning and both sides will be "leaning inward" once it is as level as it will get.

Posted by David Yauch (Member # 2754) on 11-04-2004, 09:45 PM:

Hopefully someone has figured this out and fixed it already, if not I will probably find out tonight when I go in and they'll probably blame it on me. Damn I am glad they are starting another projectionist up there to blame things on.