T3D Re: dichroics for anaglyphs

[Tom Hubin <thubin@xxxxxxxxx>]

Peter Abrahams wrote:
> 
> >I've never used dichroics, but in the interest of precise color rendition,
> >the Technicolor two strip (as well as the three strip) cameras did.
> 
> Does anyone know how they integrated the dichroic filter with the camera
> lens?  My understanding is that light has to pass through a dichroic filter
> at nearly perpendicular incidence, and that bandpass shifts as light passes
> at an angle.  I can imagine a not-too-complex system, using a transfer lens
> or a telescope, that makes the light path parallel mid-lens.  But certainly
> the light entering any lens would have many skew rays.

If the filter is between the lens and the object then the rays are
nearly parallel. This may not be so for a macro lens. If between the
lens and the film then rays are very convergent. I suspect that the
light hits the filter first.

Tom Hubin
thubin@xxxxxxxxx