RE: Best CI for process

From: Sandy King ^lt;[email protected]>
Date: 10/02/05-12:03:36 PM Z
Message-id: <a0602040bbf65c41c67ac@[192.168.2.2]>

No, I have not printed these specific two negatives, but I have
tested my materials enough to know that they will print with the same
contrast. The shape of the film and paper curves will cause a slight
difference in the exact way tonal values are rendered, but that will
not affect the overall ES of the process.

Also, as I mentioned the film here is TRI-X and it was rated at 320
so none of the negatives received enough exposure to lift the shadow
density out of the toe so toe. But this is an exposure issue, not one
of contrast.

Bear in mind, I am not claiming that a difference in DR has no affect
on the look of the print, only that it does not affect overall
contrast measured at the top and bottom of the scale, if the CI of
the two negatives is the same

Sandy.

>Have you printed these two negatives or step test to verify, with platinum
>and palladium, that that is indeed the case?
>
>
>
>Eric Neilsen Photography
>4101 Commerce Street, Suite 9
>Dallas, TX 75226
>214-827-8301
>http://ericneilsenphotography.com
>> -----Original Message-----
>> From: Sandy King [mailto:sanking@clemson.edu]
>> Sent: Sunday, October 02, 2005 11:14 AM
>> To: alt-photo-process-l@sask.usask.ca
>> Subject: RE: Best CI for process
>>
>> Eric,
>>
>> Sorry, but a part of my last message was omitted during cut and
>> paste.
>>
>> What I meant to have said was that although density range and
>> CI (or
>> Gamma, Average Gradient or whatever you want to call it) are
>> related,
>> the use of the former to talk about negative contrast can be
>> very
>> misleading because it often does not provide a good indicator
>> of the
>> effective printing density of a negative, while CI nearly
>> always does.
>>
>> For example, consider the following three cases, which
>> correspond to
>> data from testing I did of TRI-X film, at nine minutes, 13
>> minutes
>> and 20 minutes.
>>
>> Time Dmin Dmax DR CI
>> 9:00 .23 2.80 2.57 1.0
>> 13:00 .30 3.11 2.81 1.0
>> 20:00 .45 3.35 2.90 1.0
>>
>> As you can see, the DR increases significantly with time of
>> development, but the CI, which is a much better indicator of
>> effective printing density, does not. The negative developed
>> for nine
>> minutes will print with exactly the same contrast as the one
>> developed for twenty minutes, though the extra B+F of the
>> twenty
>> minute negative will require more printing time. In other
>> words,
>> increasing time of development to obtain a higher DR range over
>> that
>> needed for maximum CI is just a waste of time which also
>> results in
>> longer printing times.
>>
>>
>> Of course, if you are working with a film that has very linear
>> straight line curve there will be a better correlation between
>> DR and
>> CI.
>>
>> Sandy
>>
>>
>>
>>
>>
>>
>> >Sandy, I know they are.
>> >
>> >Eric Neilsen Photography
>> >4101 Commerce Street
>> >Suite 9
>> >Dallas, TX 75226
>> >http://e.neilsen.home.att.net
>> >http://ericneilsenphotography.com
>> >
>> >> -----Original Message-----
>> >> From: Sandy King [mailto:sanking@clemson.edu]
>> >> Sent: Saturday, October 01, 2005 11:03 PM
>> >> To: alt-photo-process-l@sask.usask.ca
>> >> Subject: RE: Best CI for process
>> >>
>> >> Eric,
>> >>
>> >> Density range (DR) and contrast index (CI) are closely
>> related.
>> >>
>> >> Read about it.
>> >>
>> >> Sandy
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> >
>> >> >
>> >> > So a discussion of density range may be more appropriate
>> than the CI
>> >> for in
>> >> >camera negatives intended for use in platinum/palladium
>> printing?
>> >> >
>> >> >
>> >> >
>> >> >Eric Neilsen Photography
>> >> >4101 Commerce Street
>> >> >Suite 9
>> >> >Dallas, TX 75226
>> >> >http://e.neilsen.home.att.net
>> >> >http://ericneilsenphotography.com
>> >> >
>> >> >> -----Original Message-----
>> >> >> From: Ryuji Suzuki [mailto:rs@silvergrain.org]
>> >> >> Sent: Saturday, October 01, 2005 7:19 PM
>> >> >> To: alt-photo-process-l@sask.usask.ca
>> >> >> Subject: Re: Best CI for process
>> >> >>
>> >> >> From: Richard Knoppow <dickburk@ix.netcom.com>
>> >> >> Subject: Re: Best CI for process
> > >> >> Date: Sat, 01 Oct 2005 16:36:06 -0700
>> >> >>
>> >> >> > Is it possible for you to post it on your web site
>> >> >> > perhaps as a PDF, I think it would be of considrable
>> value.
>> >> >>
>> >> >> PDF papers are ideal in my view but I am reluctant to
>> do this to my
>> >> >> photographic paper file. I'd rather mail a photocopy to
>> someone in
>> >> >> serious, legitimate need of the information.
>> >> >>
>> >> >> Although I might not condemn anyone putting scans
>> online quietly, I
>> >> >> probably don't want to know if my copy has anything to
>> do with it.
Received on Sun Oct 2 12:03:50 2005

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