Filming projections

[oldasdirt]

I posted this topic once under 1 F switch and process shots and might as well have gotten "duh..wasssthat??"
Has anyone here ever attempted to film a projection with super 8?Let's say you're doing a film and the script calls for your characters to be watching a film on a projector (say they're watching old home movies or it's a football coach showing game films to his players).Or lets say you're dooing a sci fi and you have your characters piloting a space ship and we need to see the alien landscape they land on outside the craft's windshield.
These are things you normally don't do in super 8 because opticals are out for obvious reasons,electronic effects look cheesy for what I'm describing,so that leaves projections.
Here are your problems (besides exposure and metering which would be different for each scenario).You would have to sync your projector to your camera (hence a 1 F switch installed in the projector and connected to your camera's remote via cable according to an old 1976 issue of Super 8 Filmaker)and you would have to modify your projector's shutter to be like your camera's shutter (one opening per frame instead of a multi blade.The flicker would be perceptible to the eye but not the camera.)
Anyone out there ever done anything similar to this?

[bigmasi]

you lost me allready *laughs*, but I'm interested on hearing answers from other people more experienced than me... I guess also the lighting would be a problem or at least something to really consentrate on. You couldn't keep the audience in darkness, and you couldn't light up the screen to keep the contrast of the projection ...so you'd have to light up the audience to match more to the screen witch would be more bright..? (unless you only want silhuettes of people) Do I make any sense? Seriously.

[oldasdirt]

Originally posted by bigmasi:
you lost me allready *laughs*, but I'm interested on hearing answers from other people more experienced than me... I guess also the lighting would be a problem or at least something to really consentrate on. You couldn't keep the audience in darkness, and you couldn't light up the screen to keep the contrast of the projection ...so you'd have to light up the audience to match more to the screen witch would be more bright..? (unless you only want silhuettes of people) Do I make any sense? Seriously.

<font size="2" face="Verdana, Helvetica, sans-serif">Absolutely.You can find much of your exposure questions answered in the American Society of Cinematographers Manual.The only problem there is the manual is written for professional studio productions and not super 8 people looking to jerry rig.
Exposure's only half the battle.The camera shutter and the projector shutter has to be in sync and identical.To understand this,you have to understand the basics of how cameras and projectors work.

[oldasdirt]

I mean, we didn't have to care about the sync?! Could it be the same with film?
No.Let's say you're shooting a scene where there is a film playing on a screen along with your actors.That is your script calls for a football coach showing game films to players and we see people watching a film projected on a screen.Un synced,you get flicker because the camera's shutter and the projector's shutter are not syncronized.Furthermore,the projector's shutter has to be changed out with a camera type shutter.There's a big difference.The camera's shutter is basically a spinning disk with a piece cut out of it (think of a pie with a piece cut out,usually 175 degrees or so,XL cameras as much as 220 degrees).The camera's claw grabs one of the perfs of film,pulls it down while the shutter is closed and once it is halted in the gate,the shutter is open again (Beaulieu cameras have a guillotine type shutter that works differently but I won't go there for this discussion).
A projector on the other hand is more like a fan or a maltese cross.The circle has more pieces cut so the shutter has two or more (5 if it's a telecine projector to sync with video)blades.This operates in reverse of a camera.The light shines through the film and in that 24th of a second it's on the screen the image is blocked again,so there will be no flicker perceptible to the eye(a two bladed shutter at 24 fps will equal 48 flickers on the screen).
Now to film a projection in the hypothetical situation I described, the camera's shutter has to open at the same time the projector's does and close when it does.The projector's shutter has to be changed to a camera type so it will flicker in sync with the camera's.Of course to the eyes of everyone on the set or location where this hypothetical film is shot there will be flicker on the screen,24 flickers per second to be a exact.
There are several ways to sync a projector to a camera after the proper shutter conversion has been made.The way it's done in Hollywood (well not much anymore with the advent of digital EFX)is that the projector and camera are equipped with syncronous motors and they are kept in sync by the AC line current.Make sense?

[bigmasi]

Originally posted by oldasdirt:
The camera shutter and the projector shutter has to be in sync and identical.To understand this,you have to understand the basics of how cameras and projectors work.

<font size="2" face="Verdana, Helvetica, sans-serif">I been working with video more, but I know the problem. With video you also have to change the shutterspeed (electronic) when you are filming television screens and stuff... It's been years since the last time I had to do it, but if I remember correctly we just had to have the correct speed ... I mean, we didn't have to care about the sync?! Could it be the same with film? because the projection doesn't have black or blank between the frames and if the sync is not correct would it still be ok when filmed and projecting again.. (or transfered by other ways)

Ps. I'm not sure if I get understood right because english is not my first language and I don't know all the technical words...

I the projection is filmed in a way that the edge of the two frames is in the middle of the screen... would it still be ok, just if the edge is not moving (slower/faster filmspeed)

<font color="#a62a2a" size="1">[ April 15, 2004 12:30 PM: Message edited by: bigmasi ]</font>

[bigmasi]

eyah, I get it... actually I don't know much about projectors and now when I think of it ...I was kind of thinking that they don't have a shutter. Well, at least for now, I don't have to do that kind of shot so... I'm happily just forgetting about all of this *laughs* no, really, keep posting. It's interesting.

Ps. check the topic, "panning and tilting timelapses". I really could use some help with that...