T3D Now yer in trouble (again)

[vidi@xxxxxxxxxxxxx]

   I guess I should have read all the posts before I sent my 1st response:

>   I will be interested to see how we spec a lens used as an eyepiece.
>I'm all too familar with specing a lens for real images, but I've never 
>understood how to spec a lens which is used for virtual images.  Can 
>someone come up with the list of specs. which need definition, or can 
>this designer give us the list to fill in the blanks?  I am most 
>interested in how to spec the chromatic abberations evident in the virtual 
>image.

   I see John B. has assembled somewhat of a list and it's a big leap forward.
It still seems we should get a list from the designer with some details of the 
definition of the spec.  Do we (John B.) know what is offensive in a viewer lens?
I know if the lens in one of my digital camera designs is not adequate, I end up 
with a degraded "Read Rate" on my machine.  This "Read Rate" is an excellent metric 
for image quality for me.  What metrics do we use in a visual system and how will 
we measure those metrics?  Do we just accept what he tells us they will be?  Case 
in point is the Magnification!  How do you measure mag in a virtual imaging system?
By the classic formula method using the focal length of the lens or by empirical 
measurement.  Same goes for the apparent chromatic abberations.

   Just some thoughts.


John V.





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