[OM] So here's the deal...

[usher99]

>But then I went to Wiki looking for some support for my supposition and
> see that it's far more complicated than I thought. For macro work it
> says that DOF is better thought of in terms of magnification and focal
> ratio which then makes DOF (almost) independent of focal length.

Well Chuck I think is correct, but then he has Dr. Focus as an in house 
consultant.
At least with the Z. 80mm macro pupil magnification is not an issue as 
it is symmetric.
This link I think helps a tad:
http://toothwalker.org/optics/dof.html
See about 2/3 way down--pupil magnification is not terribly mysterious.


Now what  happens  with light loss and DOF when the floating elements 
move in macro lenses??
That is mysterious to me.  John Shaw claims less light loss than pure 
extension.
Hmm, I should check with  the CV125 apo Lanthar macro--I have enough 
extension to do that with the auto tube etc.
Only Dr. Focus would be interested though.

Mike

PS Perhaps AG should try for a  workshop in the UP--but only when it is 
MUCH warmer--unless I get to use the 3T that is.
-- 
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