Shooting a projection on a movie theater screen

[Lisa Wiegand]

Hi All,

I am going to be shooting a music video & the band needs to perform in front of a movie screen with film being projected on it. We will be shooting on location in a theater using their projector. Does anyone have tips for this situation? I am particularly wondering about how to insure sync without flicker. The artists will be lip-syncing while the projector is running. Any suggestions are welcome. Thanks.

 

Lisa Wiegand

[David Mullen ASC]

Well, shooting in film, you'd normally want to get a special projector with a single-bladed shutter (like are used for rear-projection process shots) and sync the camera to the projector with a sync box (don't ask me how, I've never done it). Youd have to get used to the fact that the operator and video tap will see NO image being projected since it's only being flashed when the film camera's shutter is open.

 

With a typical projector with a two-bladed shutter, you'll have a pulsing to the image if you shoot live without syncing it. Often that's acceptable as a look.

 

I wonder though if you shot in 24P HD with no shutter (i.e. at 1/24th of a second) you'd get rid of the flicker since the camera was always exposing the image with no gaps?

[Wendell_Greene]

Have you considered using a video projector to provide the images on the screen the band will play in front of ?

[Lisa Wiegand]

Thanks so much guys. I was able to convince the producers to get us a green screen and do a composite in post. But, I am now very curious about the 24P HD at a 1/24th shutter, Hmmmm.

 

Lisa

[David Mullen ASC]

Thanks so much guys.  I was able to convince the producers to get us a green screen and do a composite in post.  But, I am now very curious about the 24P HD at a 1/24th shutter, Hmmmm.

 

Lisa

<{POST_SNAPBACK}>

 

Panavision has a theater and HD cameras, so you could test it there.

[Dominic Case]

With a typical projector with a two-bladed shutter, you'll have a pulsing to the image if you shoot live without syncing it. Often that's acceptable as a look.

David, are you sure that's correct?

 

It's true that with a single-bladed projector you wil need to sync the camera to it, and then everything is fine (so long as you have the right boxes to do the syncing - I'm not sure which device leads and which chases).

 

But if you stick to a normal 2-bladed shutter, then regardless of the exact phase of sync, every frame of negative will get 1/96th sec of exposure - which might all be from one projector "flash" or may be from two successive ones (which might be from the same projected film frame, or two different ones). If the projector isn't quite 24fps, then there would admittedly be a pulse equal to the difference of speeds - a projector that was running at 25 would give the equivalent of about one printer point of variation every second: barely visible. But there wouldn't be the the problem of rolling out of sync that you would have with a single-blade shutter. So you can get away with shooting a conventional screen with no special set-up.

 

The downside is that the 2-blade shutter loses you one stop of light.

[David Mullen ASC]

It's just been my experience shooting 16mm and Super-8 projection with a film camera, all at 24 fps, without a sync box that what you get is sort of a faint pulsing. Now maybe that's just due to a lack of crystal speed on the projector's part, I don't know.

[John Sprung]

It's just been my experience shooting 16mm and Super-8 projection with a film camera, all at 24 fps, without a sync box that what you get is sort of a faint pulsing.  Now maybe that's just due to a lack of crystal speed on the projector's part, I don't know.

<{POST_SNAPBACK}>

It's a combination of the camera and projector not being in sync, and the camera having a shutter angle other than exactly 180 degrees.

 

For instance, with a 160 degree shutter in the camera and a projector with two 90 degree blades, you could get 90 degrees of light plus 70 degrees of darkness if a projector shutter open time falls completely within the camera shutter open time. Or you could get 90 degrees of dark and 70 degrees of light if a projector shutter blade falls completely within the camera shutter open time. As they drift out of sync, you slowly ramp back and forth between 90 light - 70 dark and 90 dark - 70 light. Sync would get you a constant exposure, but you'd have no way of knowing or controlling where each take lands on that ramp. For that, you need both sync and phase.

 

The other big problem with this is that you can get two different projection frames in the same camera frame, which makes a double image.

 

Bottom line, you need both sync and phase for the best results.

 

 

 

-- J.S.

[Ed Chapman]

This technique has been used in theatrical films from the beginning. Yes, you do have to synchronize the projector with camera. In LA the Hansard family still owns and operates 35mm projectors and the syncing equipment. The film prints need to be editted and timed for proper color temperature to balance projection color temperature with the lighting color temperature. Tests should be made to determine whether front projection or rear projection would be best for the lighting scheme. Video projection could also be used. The playback would need to be 24fps and a sync box used if shooting 24 fps. For a music video ushooting at 30fps wouldn't be a big deal and save money on the playback gear. You still need a sync box. The projector probably wants to have a line doubler to eliminate the "scan line" look to standard interlace video projected that large. Even doing it as a post gag requires some lighting skills to give the impression of reflected light from the screen and the usually desired "projector beam" in the "smoke filled theatre.