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Author
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Topic: Digital Drive-In Projection
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Barry Floyd
Phenomenal Film Handler
Posts: 1079
From: Lebanon, Tennessee, USA
Registered: Mar 2000
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posted 11-22-2005 09:55 AM
I was contacted by a guy who wants to propose to his girlfriend this Wednesday night at our theatre. They had their first date there, and he wanted to propose there as well.
During our phone conversation, he stated he wanted to bring a small video projector and show about 10-15 minutes of footage he has taped of well-wishes from friends, family, etc. I told him I was VERY doubtful if it would work because of the lamp size in the projector, the wrong lens sizes, the throw distance, etc., but he said he wanted to try.
I met him out at the theatre last night after work, and he pulled out this little conference room table video projector, about the size of a small VCR. I was thinking to myself ... NO Way was this going to work as we were standing 275 feet away from the screen. He plugged it in and I must honestly say... I was AMAZED. It actually worked. Albeit, the mismatched lens made the picture about twice the size of the screen, and the picture was a little dark... but with about twice as much light and the right lens... it definetely has potential for something. (Advertising slides, private rentals, etc.)
He played part of his tape, and I walked up to the bottom of the screen expecting to see pixels the size of basketballs.... it was perfect.
This wasn't some fancy digital cinema thing, this was an ordinary business-style conference room table video projector.
I believe the name brand was "In-Focus", and the model number was the "Screenplay 5000"
Thought you guys might like to know.
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 11-22-2005 10:57 AM
The name of the game is "Lumens". Most drive-ins fall far short of the 16 footlamberts specified by standard SMPTE 196M. In fact, SMPTE Recommended Practice RP12-1997 "Screen Luminance for Drive-In Theatres" specifies:
quote: 4 Luminance level
4.1 In an ideal situation, when permitted by the technology of motion-picture projection, and when the viewing environment is sufficiently close to that of the indoor theater, the screen luminance and distribution shall be that specified in ANSI/SMPTE 196M, 16 fL ± 2 fL (55 cd/m2 ± 7 cd/m2), as measured from a position on the longitudinal centerline of the ramp area and midway between the foremost and rearmost ramps. 4.2 The recommended minimum luminance at the center of the screen shall be 7 fL (24 cd/m2), as measured from the central position defined in 4.1. 4.3 When maximum compromise must be made, as discussed in annexes A.1 and A.2, the luminance at the center of the screen, measured from any car position, shall in no case be less than 4.5 fL (15 cd/m2).
So, even 4.5 footlamberts is not unusual (but not ideal) in drive-in theatres. Assuming a freshly painted matte white screen with a gain of 0.9, a 30 x 40 foot video image would require (30 x 40 x 4.5) / 0.9 = 6000 lumens to get 4.5 footlamberts.
Since the InFocus ScreenPlay 5000 has a rated output of only 1100 lumens, you likely were well below 1 footlambert on your screen. You're drive-in must have very little ambient light shining on the screen!
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