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shooting a 16mm projector


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#1 Christian Janss

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Posted 14 November 2006 - 01:15 PM

I'm shooting a scene where a guy is watching a 16mm film projected onto a screen or white wall. I've done some tests and all I can get from the projector is about a T2.0 on the screen surface (read by a spot meter), using 500 ASA film.

Question: How can I get more of an exposure off the screen?

I'd like to have the screen one stop overexposed, say at a T4 or ideally at a 5.6. The thing cutting down the light the most is the lens of the projector, but without that the film can't be focused or even projected very well at all.

I was thinking of using B&W print that was overexposed, but I can't think of any other tricks to do... any suggestions will be much appreciated.

thanks
Christian Janss

By the way, I'll be shooting on Super 16.
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#2 Jonathan Bowerbank

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Posted 14 November 2006 - 05:22 PM

I suppose that type of screen you're using would make a difference. A more reflective screen would probably give you a better exposure.

Or you can find a better projector, with higher wattage I suppose.
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#3 Chris Keth

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Posted 14 November 2006 - 08:01 PM

I think either you find a different projector xenon projectors that are meant for larger venues are brighter) or you project something that is already overexposed.
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#4 Laurent Andrieux

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Posted 14 November 2006 - 09:16 PM

Projecting something that is overexposed may not be satisfying...

What power is the projector you have tested ?

How far from the screen is it ?

It may be more powerfull if closer to the screen, and then the question will be of the focal length of the projector lens.

The properties of the screen can do a lot, as mentionned.

If your projector is already powerfull and if you have no way to get it closer from the screen and if you have a good budget for this shot, you can use a 3M scotchlite screen, it's very powerfull. It's used for front projection compositing on set. You set its lumination by the angle the camera makes to the frontal plan of the screen. You'd easily get a T 11 with that material !
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#5 Christian Janss

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Posted 15 November 2006 - 03:03 PM

First, thanks a lot for the recommendations, I'm on the search for a more powerful projector or bulb.

The projector I tested is basically the old kind they have in high schools, a Bell & Howell (I think) with a 750w bulb.
It can be relatively close to the screen, say 6' - 8', but even then I'm not getting much out of it.


Question:
Where can I find a "3M scotchlite screen"? For rent? (I'm in Philly, but I can drive up to NYC for it if necessary)

It sounds expensive, is there anything short of pro-quality rear projection I could substitute.


Also, do you think B&W would help more than color?
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#6 Laurent Andrieux

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Posted 15 November 2006 - 06:29 PM

Ok, it's good to have these precisions.

I am not a specialist for rear projection, but I think it's a pain in the neck to setup, won't necessarly be more powerful and involves many problems, such as flip-flop left to right to the image that may be a problem depending on what you are projecting...

EDIT : Mind, that as you mentionned the fact you're shooting super 16, the camera and projector should be synchronized, I think... See this with both camera operator and AC.

Anyway, if I were you, I'd rent a more powerfull projector. No necessarly need for a scotchlite screen since it sounds you're actually running on a low budget...

A scotchlite screen should be avaible for rent around NYC or Philly but as a studio rental, not sure you could find a movable one...

There must be a 2 kW projector to rent somewhere around ! you'd get about 2 stops higher, that would be ok, I guess.

What do other people think about that ?

EDIT : don't think W/B should help in anyway, vs color...
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#7 Christian Janss

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Posted 21 November 2006 - 07:46 PM

Yah, I think the rear projection stuff is too complicated for this. But I have ordered a brighter screen, it's glass beaded and puts out a rating of 2.5 gain (as compared to a 1.1 gain from matte white).

If that's not enough I'll have to rent one with a xenon bulb. I have a line on one here in Philly, but I'm afraid it will cost a pretty penny to rent. Be that as it may, thanks a lot for the advice.


As far as timing the projector to the camera, could I do that by undercranking the camera? That would make the projected image look speeded (spead?) up but would it ensure that the camera shutter didn't block out the projected image (or at least not block it out too much)?

I just read a posting where they trimmed the shutter to 210 degrees, what would that do?


An added bonus of these approaches would be to bring in more light, which I need anyway. Which will be all the more tough since the director now demands we use 200 asa as opposed to the original 500. yikes.
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