Archived posting to the Leica Users Group, 2002/01/04

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Subject: Re: [Leica] freshness (was Mark Rabiner's)
From: Rei Shinozuka <shino@ubspw.com>
Date: Fri, 4 Jan 2002 15:07:36 -0500 (EST)

thanks for the advice.  i do have a little xrite densitometer.

one thing you can always count on every roll: some dmax (the leader) and
some film base (space after last frame).  i usually file both peices in
with my negatives so i can check them at a later date.

may i ask why do you pick -3 and +5 from normal exposure?  this corresponds
to zone II and zone X.  i usually benchmark to zone I (D=FBF+0.10) and
VIII (D=FBF+1.20).

thx

- -rei


> From: "Don Dory" <dorysrus@mindspring.com>
> 
> Rei, the only sure test would be to create a test strip much as the
> commercial labs use.  First frame blank, second frame gray card exposed per
> the meter, third frame minus three stops, fourth frame at plus five stops.
> 
> To make this work you would have to create a standard set to compare with
> known good chemistry or from a well set up commercial lab that runs
> commercial test strips.
> 
> The first frame tells you if your fix is any good or whether there is some
> source of dichroic fog in the system.
> 
> The third frame tells you the speed point of the process.   This needs to be
> looked at in conjunction with contrast as if this point rises as well as the
> middle gray then contrast stays the same but everything is overdeveloped or
> the fix is going south which you can tell from the blank frame.
> 
> The second frame minus the third frame tells you the contrast index of your
> system.  If the developer is just going south you will see it in the
> contrast assuming the FB + fog stays constant.
> 
> The fifth frame indicates ability to create dMax, this would be important if
> you were experimenting with higher dilutions.
> 
> All of the above implies the possession of a densitomiter or access to one.
> 
> E-mail me if you have any questions.
> 
> Don Dory
> dorysrus@mindspring.com
> 
> --
> To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html
> 


- -- 
   Rei Shinozuka  shino@ubspainewebber.com 212-713-6256 FAX: 212-713-1482
   UBS Warburg  Fixed Income  Quantitative  Research,   UBS  Warburg  LLC
   1285 Avenue of the Americas,    11th Floor,   New York,  NY 10019-6028
 -----------------------------------------------------------------------------
"The  X Consortium  requests that the  following names be used when  referring 
 to this software: X,  X Window System, X Version 11, X Window System, Version 
 11, X11." (NOT "X-WINDOWS"!!!)      -X man page (parenthetical exegesis mine)

- --
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Replies: Reply from "Don Dory" <dorysrus@mindspring.com> (Re: [Leica] freshness now test strips)