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

Subject: Re: [OM] So here's the deal...
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Thu, 16 Dec 2010 22:54:10 -0500
I dub THEE Dr. Focus.

Dr. (just) Flash



On 12/16/2010 8:57 PM, usher99@xxxxxxx wrote:
>> 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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