P3D Re: Stretcho-TDC

[Bill Davis <bd3d@xxxxxxxxxxxxx>]

>
>From: Michael Georgoff <Michael_Georgoff@xxxxxxxxxxxxxx>
>The TDC 116 has 5" lenses on it.  These length lenses are not optimal for my
>use,    

My projector is a TDC with 5" lenses too.  I took a wall out between rooms
to get a 25 ft. throw. Now I can just fill a 50x50 screen.  
 
>
>Okay, so what's problem?  Well, me being the projectionist, I've gotta be
>the farthest human from the screen, so the image which is already small by
>virtue of having 5-inch lenses is even smaller given the distance away that
>I am, lonely projector guy way in the back...  

I think we should start a TDC Lonely Projectionist's list.

>
>
>Okey-dokey, being a curious sort, I slowly
>walk up closer to the screen, and it STILL does not look approximately right
>(no z distortion) until I'm 3 or 4 feet away.  Huh?  It appears that ortho
>is 3 or 4 foot away.  Izzat right?  5" lenses, 15 foot throw, ortho = 3 or 4
>feet?


>  I will even accept long-winded
>math if that helps me understand..

I got 700 on my math SAT, but that was 25 years ago.  I don't try
long-winded stuff these days.  

This formula I can handle.  For Realist format images, multiply the
onscreen image height by 1.50 (use any units you want)  Measure this
distance back from the center of the screen.  Put your eyes there.

Size is everything.  The larger the image, the further back Uncle Ortho sits.

According to the manual, 5" lens at 19 1/2 ft fills a 40x40 screen with
American standard stereo, so your 15 ft would yield an image roughly 30x30,
big by television standards, but you may need to invest in a SawZall.
According to the math that puts Ortho at 45 inches, which is about where
you found it.  

Ortho it would theem. 


>Thanks!
>
>Michael Georgoff
>San Jose, CA
>


Best regards,
Bill Davis
mailto:bd3d@xxxxxxxxxxxxx


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End of PHOTO-3D Digest 3236
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