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[pure-silver] Re: TMax 100 and 400 dev. times, rec. same - ?
- From: Janet Cull <jcull@xxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 7 Jun 2007 19:27:23 -0400
Richard, thank you!
On Jun 7, 2007, at 6:22 PM, Richard Knoppow wrote:
----- Original Message ----- From: "Janet Cull" <jcull@xxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Thursday, June 07, 2007 10:57 AM
Subject: [pure-silver] TMax 100 and 400 dev. times, rec. same - ?
What do you think about this? The recommended dev. time for TMax
400 in dil. B HC110 is 6 min. (according to the massive dev.
chart). For TMax 100 in the same developer, they recommend 6
(and/or 7) minutes.
For TMax 100 at 400 I think they recommend 11.5 min.
Does that make sense to you?
Thanks.
Yes, because we are comparing two different emulsions with
different inherent speeds. Originally, T-Max 100 and T-Max 400 were
designed to have approximately the same _normal_ development times
so that they could be processed together. Later versions, or
perhaps its just later tests showed some difference is necessary.
The second time is for push processing, not normal processing.
The rule of thumb is that to push film about one stop the
development time is increased about 1.4 times. To push it another
stop the time must again be increased about 1.4 times or about 2
times the "normal" speed. That is what you are seeing in the chart
recommendation for T-Max 100.
Now, the difference between T-Max 400 at EI-400 and normal
processing and T-Max 100 at EI-400 and getting two stop push
processing is that the push procesing will also increase contrast.
In fact, the contrast will increase about one paper grade for each
stop of push. That means the pushed T-Max 100 negatives may be very
contrasty.
The idea of push processing is that when a negative is
underexposed most of the desirable image will be recorded on the
"toe" region of the film curve where the contrast is considerably
lower than on the "straight line" portion used for normal exposure.
In order to make the underexposed toe more printable its necessary
to increase its contrast. Of course, this also increases the
overall contrast of the negative. Where the original scene was not
too contrasty and most of the desireable image is on the toe this
can result in fairly normal tone rendition, but, were the scene was
of normal contrast or some of the image is recorded on the middle
part of the curve, the negative may be difficult to print because
of excessive contrast.
Since grain is increased with increased development time the
advantage usually lies in the direction of using faster film rather
than push processing slower film.
There is no real increase in speed when pushing. The increase in
the toe contrast does allow better prints to be made from
underexposed negatives but at the cost of distorting the tone
rendition.
In the same way its not really possible to pull negatives.
Reducing development time simply decreases contrast. Of course, it
also decreases overall density but the pulled negatives will have
to be printed on high contrast paper to get normal tone rendition.
However, this is usually an easier process than the burning and
dodging often necessary for pushed negatives.
The data sheets for T-Max, both old and new, are still on the
Kodak web site.
BTW, I think there is less difference between the two than is
usually thought. From what I've been able to learn the T-Max films
were always coated in the color film plant so production was not
moved when the other films were moved to this coating facility. I
do think there may have been changes in the overcoating. In any
case Kodak seems to have run new sensitometric tests on the films
resulting in slightly changed development charts.
Another BTW, if you need to push HC-110 is not the best choice.
I suggest using a Phenidone based developer like Kodak Xtol, Kodak
T-Max (either one will do for roll film), or Ilford Microphen.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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Other related posts:[pure-silver] TMax 100 and 400 dev. times, rec. same - ? [pure-silver] Re: TMax 100 and 400 dev. times, rec. same - ? [pure-silver] Re: TMax 100 and 400 dev. times, rec. same - ? [pure-silver] Re: TMax 100 and 400 dev. times, rec. same - ? [pure-silver] Re: TMax 100 and 400 dev. times, rec. same - ? [pure-silver] Re: TMax 100 and 400 dev. times, rec. same - ?
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