Re: Focus shift (was Re: Reciprocity failure)

[Michel Wurtz - LTE <mw@xxxxxxxxxxxxxxxxxxxxx>]

JoePaduano@xxxxxxx wrote:
> 
> Just a note-color infrared film does not require a focus shift, as the two
> color image layers record visible light.
>                                                      Joe Paduano

Yes, this is what the Kodak doc says, and it's true if you admit that
the red layer may be fuzzy, or if you choose to work with an aperture
of 11 or smaller...
I think that the best is to have the same accuracy both in IR and
visible light, so I choose to do a half focus shift and verify the
aperture needed to avoid fuzzy - this is a feature of each lens (but
more complicated with zooms). If you have indication of depth of
field, the maximal aperture to use is the one indicated by the red
dot indicating focus shift for IR.

I know that a drawing would be better, but I prefer not to put a (small)
jpeg attachements without asking : does the policy of this list agree ?

-- 
Michel Wurtz	ENGEES - Laboratoire Territoires & Environnement
		1, quai Koch - BP 1039, F-67070 STRASBOURG cedex
		Tel: +33 3.88.25.34.62    Fax: +33 3.88.37.04.97

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