P3D Re: kodachrome vs provia f

[kiwi1957@xxxxxxxxxx]

>  ------------------------------
>  
>  Date: Mon, 14 Feb 2000 12:26:50 -0800 (PST)
>  From: L <jet_lk@xxxxxxxxx>
>  To: photo-3d@xxxxxxxxxxxxxxxxx
>  
>  
>  I actually found Kodachrome to have a slight green
>  shift.  

Another factor in a film's color balance is its aging. Kodachrome with a
green shift is an indication that it is *too fresh*! 

When film *emulsions* are manufactured, they go through an aging process
before they are sliced, diced, and packaged. Freshly manufactured emulsion
does have a green bias. As film ages, it shifts toward a neutral balance and
is packaged for shipment to distribution centers or retailers. As is ages,
it shifts toward magenta some time after the expiration date. Unless you
have your film in a deep freeze, the color balance will always shift it
ages. 

When Kodak first introduced K14 process film (in the mid-70's) a common
complaint was a green bias. I bet it's the same green bias you are
encountering. Back at the time of K14 introduction, it turned out that Kodak
shipped some emulsions too soon. (This was reported in Modern Photography.)
The challenge for a film manufacturer is to be able to ship film to its
retailers with a long enough shelf life so that the retailer can sell it
before the expiration date. The "very freshest" film is not always the best
thing. 

*Very generally*, assuming appropriate cool dry storage--but not frozen
storage--most consumer films are at their prime balance within a year before
their expiration date. 






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