Archived posting to the Leica Users Group, 2000/08/07

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Subject: RE: [Leica] Shadow boxing
From: "B. D. Colen" <bdcolen@earthlink.net>
Date: Mon, 7 Aug 2000 16:30:41 -0400

Well, JD, the numbers make sense...but....Why do I keep thinking that being
told you should want flare in a lens because it's a "good think" is a bit
like being told that you want a dishwasher that leaks because then you can
use the same water to wash the dishes and the kitchen floor? :-)
B. D.

> -----Original Message-----
> From: owner-leica-users@mejac.palo-alto.ca.us
> [mailto:owner-leica-users@mejac.palo-alto.ca.us]On Behalf Of John
> Brownlow
> Sent: Monday, August 07, 2000 4:16 PM
> To: LUG
> Subject: Re: [Leica] Shadow boxing
>
>
> on 7/8/00 4:01 pm, Craig Roberts at croberts@zoomtel.com wrote:
>
> > "The flare helps to get to that threshold so it takes slightly
> less image
> > exposure to show up as density." - Ed
> >
> >
> > Hmmmm.  Thank you, Ed, but this sounds...almost
> literally...like smoke and
> > mirrors, or a sophisticated practical joke.  I prefer not to
> think about it
> > any longer.  My brain hurts.
>
> Oh, Craig, sit down, take some Advil and listen!
>
> Say it takes 5 units of light to 'activate' a film grain so it can be
> developed.
>
> Let's say you're getting 4 units of light in through the
> contrasty lens, so
> the grain doesn't get developed. So no shadow detail there.
>
> In the flarey lens let's say you get 1 unit of flare all over the
> film. Now
> add that to the 4 units coming in as before, you get 5 units.
> Ergo, you get
> shadow detail.
>
> That's the theory and the number mean nothing and the reasons why it might
> not work in practice are blindingly obvious even in this little thought
> experiment, but the concept is pretty simple.
>
> --
> Johnny Deadman
>
> http://www.pinkheadedbug.com
>
>
>