Archived posting to the Leica Users Group, 2002/02/17

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Subject: Re: [Leica] OT: 16mm projector shutter speed
From: "Mike Durling" <>
Date: Sun, 17 Feb 2002 20:12:46 -0500
References: <> <>

That's correct that sound speed should be 24fps in the US.  Often the
shutter was designed to be open for more than 180 degrees so you could have
a longer shutter speed than 1/48.  Of course one on-off cycle is 1/24 but
there is no guarantee that it is running on-speed.  Still even then if you
shoot at 1/30 there is no way to tell if a given frame is timed with more or
less of the open part of the cycle.

Mike D

- ----- Original Message -----
From: "Bernard Cousineau" <>
To: <>
Sent: Sunday, February 17, 2002 5:58 PM
Subject: Re: [Leica] OT: 16mm projector shutter speed

> > i have an old 16mm projector that i got at a thrift store.  i plan to
> > try using it to light some nudes--i'm going to try projecting a movie
> > onto my model.  i'm windering how to be sure i get the right amount of
> > exposure, since my light source will be flickering.  i'm *thinking* the
> > shutter speed on a movie projector is 30 fps.  if that's correct, then
> > i'm thinking shooting at 1/30 will guarantee me getting only one
> > illumination per frame.  is that right?
> Brad,
> Your projector should run pretty close to 24 fps, but many projectors will
show each frame twice to minimize the apparent flicker. This means that each
frame will be on screen for either slightly less than 1/48th or 1/24th. On
top of this, some
> projectors have been modified to run at 30 fps, showing each frame only
once. The purpose of this is to facilitate cheap video transfers. If you are
in a country where video runs at 25fps, your projector may have been
modified to run at that speed.
> What I suggest is to run a test first at speeds between 1/8th and 1/60th
and see what works best.
> The easy way out, of course, is to dupe the frames that you want and use a
slide projector.
> Bernard
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In reply to: Message from bourgeois and biblical <> ([Leica] OT: 16mm projector shutter speed)
Message from Bernard Cousineau <> (Re: [Leica] OT: 16mm projector shutter speed)