Mailinglist Archives:
Infrared
Panorama
Photo-3D
Tech-3D
Sell-3D
MF3D

Notice
This mailinglist archive is frozen since May 2001, i.e. it will stay online but will not be updated.
<-- Date Index --> <-- Thread Index --> [Author Index]

Re: Shift lenses

  • From: P3D John Bercovitz <bercov@xxxxxxxxxxx>
  • Subject: Re: Shift lenses
  • Date: Tue, 27 Aug 96 09:24:35 PDT
Wm. C. writes:

> Keep the film plane parallel to the screen.
> As the projection beam is steered through a prism it acquires a keystone 
> distortion parallel to the beam. This distortion is then neutralized by 
> the screen being parallel to the film plane. 

Can anyone explain how this cures keystone?  It's not intuitively obvious
to me.

> Melles Griot has the formulae for an apex angle for a chosen deviation.

Yeah, I've done that calculation numerous times.

Thanks,
John B


------------------------------