Re: New 3D lens announced

Bob Aldridge

Yes. With a single lens the centre of each "bunch" of rays (left and right) MUST cross in the optical centre of the lens. If they don't they will be bent by the lens and destroy the image...

The unavoidable problem with this is - as has been stated - the bunches of rays Cannot be parallel.

Bob Aldridge

On 10/04/2021 21:18, Antonio F.G. via wrote:
On Fri, Apr 9, 2021 at 03:09 PM, Depthcam wrote:
> By the way, such mirror design could produce parallel shots if the angle of the mirrors were adjusted for that.
Actually, no.  This will only work if a  mirror adapter is mounted on a set of two lenses  - as is the case with the Leiz Stemar or the Zeiss Stereotar C.  When you mount a mirror adapter on a single lens and keep the optical axes parallel, each side is viewing one side of the scene - just as if there were no adapter. In order for a left and right image to be recorded of the same scene, the optical axes MUST be converged.
I was not sure about this, but nothing like making a drawing of a "perfectly" parallel mirror adapter, with mirrors exactly at 45°:

The rays from a point at infinity arrive in parallel to the mirrors, and they send them to the lens in parallel as well. Therefore the lens prints a single point in the sensor. This is exactly the same as if the mirrors were not there.

It seems that the way to get two separate L&R images of the point is to deviate the mirrors somewhat away from 45°.
But I am still not sure whether this implies necessarily convergence of the two optical axis (may need another drawing:-)


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