Re: [photo-3d] Re: 3d equations- New Scientist

["bart kelsey" <attraxe@xxxxxxxxxxx>]

Dear Chris

Thankyou for taking the time to respond to my questions regarding 3d 
equations.

You clarified the second and third questions I posed however, I am still a 
bit unsure when applying equation 1. May I trouble you one last time to end 
my frustration?

I can see from the geometry where z= sf/p comes from, but not z = 2h - 
(sf/p).
I have it in my head that the total parallax should be z = 2h + (sf/p).
Could you straighten me out on this one please.

I understand that the value of P will change depending on the value of h. 
This wasn’t the point of confusion. In the example of no axial offset I 
substituted Mfs/p for Z in the equation P = (Ve)/(e-Z). The equation reduced 
to P = (Vep)/ (ep – Mfs) which gave the correct answer.
However, substituting  h = 0 into equation 1 did not reduce it to P = (Vep)/ 
(ep – Mfs), but to P = (Vep)/ (ep + Mfs), thus giving the incorrect answer. 
This is why I asked, why doesn’t equation 1 work when h = 0? I'm still 
unsure of this one.

Thanks for pointing out my error in the case of axial offset.

I look forward to a response at your convenience.

Thanks

Bart

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