Light source for Pyro negs

In article ,
"Jim Phelps" wrote:

Use and GRADED paper to get the 'benefits' of pyro. The light source
does not matter so much. DO NOT use VC paper, because it defeats the
whole purpose of pyro.


This information is completely wrong.

Consider the source,...and I don't mean light. Unless your equating
light with dimly lit :-)
--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

In article ,
"Jim Phelps" wrote:

Use and GRADED paper to get the 'benefits' of pyro. The light source
does not matter so much. DO NOT use VC paper, because it defeats the
whole purpose of pyro.


This information is completely wrong.

Consider the source,...and I don't mean light. Unless your equating
light with dimly lit :-)
--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

"Jim Phelps" wrote in message ...
"Uranium Committee" wrote in message
om...


The 'benefit' of a stained negative is the stain, which takes the
place of silver density for papers that are sensitive only to blue.
The stain is yellowish-green, and since these stains block blue light,
they are seen as extra density by blue-sensitive paper. Variable
contrast paper DOES see 'green', and so the stain DOES NOT act as
density for VC papers.

Use and GRADED paper to get the 'benefits' of pyro. The light source
does not matter so much. DO NOT use VC paper, because it defeats the
whole purpose of pyro.


This information is completely wrong.

No, it's correct!

FACT: the stain is yellowish-green

FACT: the stain TRANSMITS yellowish-green and STOPS blue light

FACT: graded paper is insensitive to green or yellow light

FACT: VC paper is sensitive to green light

CONCLUSION: the stain ADDS density as far as graded paper is
concerned, and DOES NOT add density as far as VC paper is concerned.

In addition, the green light that the stain allows through softens the
contrast in the most-heavily-exposed areas, precisely the opposite
effect that occurs when graded paper is used. Attempting to use VC
filtration to raise the contrast simply ignores the stain again, and
you end up fighting against the stain.

"Jim Phelps" wrote in message ...
"Uranium Committee" wrote in message
om...


The 'benefit' of a stained negative is the stain, which takes the
place of silver density for papers that are sensitive only to blue.
The stain is yellowish-green, and since these stains block blue light,
they are seen as extra density by blue-sensitive paper. Variable
contrast paper DOES see 'green', and so the stain DOES NOT act as
density for VC papers.

Use and GRADED paper to get the 'benefits' of pyro. The light source
does not matter so much. DO NOT use VC paper, because it defeats the
whole purpose of pyro.


This information is completely wrong.

No, it's correct!

FACT: the stain is yellowish-green

FACT: the stain TRANSMITS yellowish-green and STOPS blue light

FACT: graded paper is insensitive to green or yellow light

FACT: VC paper is sensitive to green light

CONCLUSION: the stain ADDS density as far as graded paper is
concerned, and DOES NOT add density as far as VC paper is concerned.

In addition, the green light that the stain allows through softens the
contrast in the most-heavily-exposed areas, precisely the opposite
effect that occurs when graded paper is used. Attempting to use VC
filtration to raise the contrast simply ignores the stain again, and
you end up fighting against the stain.

"Uranium Committee" wrote in
message
...
"Jim Phelps" wrote in message
...
"Uranium Committee" wrote in
message
om...


The 'benefit' of a stained negative is the stain, which
takes the
place of silver density for papers that are sensitive
only to blue.
The stain is yellowish-green, and since these stains
block blue light,
they are seen as extra density by blue-sensitive paper.
Variable
contrast paper DOES see 'green', and so the stain DOES
NOT act as
density for VC papers.

Use and GRADED paper to get the 'benefits' of pyro. The
light source
does not matter so much. DO NOT use VC paper, because
it defeats the
whole purpose of pyro.


This information is completely wrong.

No, it's correct!

FACT: the stain is yellowish-green

FACT: the stain TRANSMITS yellowish-green and STOPS blue
light

FACT: graded paper is insensitive to green or yellow light

FACT: VC paper is sensitive to green light

CONCLUSION: the stain ADDS density as far as graded paper
is
concerned, and DOES NOT add density as far as VC paper is
concerned.

In addition, the green light that the stain allows through
softens the
contrast in the most-heavily-exposed areas, precisely the
opposite
effect that occurs when graded paper is used. Attempting
to use VC
filtration to raise the contrast simply ignores the stain
again, and
you end up fighting against the stain.
It does add density for the blue sensitive component of
variable contrast paper but less for the blue and green
sensitive layer. This has the effect of modifying the
characteristic curve of the paper. It creates what is
effecively a shoulder which flattens highlight density. This
may or may not be desirable. Some claim to get better prints
this way. It probably depends on the subject matter as much
as anything else. Essentially, the stain image acts as a
mild contrast reducing mask when used with variable contrast
paper.
When used with graded paper the stain image simply adds
to the silver image. This is not an advantage or
disadvantage although it makes measuring the effective
density of the iamge more difficult since the densitometer
must have a filter which matches the spectral response of
the printing material. I am not sure about the validity of
the idea that the stain image masks grain since it must
mimic the grain. Any diffusion of the stain away from the
grains where it is generated would affect resolution and
sharpness. This is not a common effect of Pyro development.
Pyro developers also harden or tan the gelatin in a way
which is proportional to the image density. This effect is
used to produce relief images for dye transfer and other
printing methods. In ordinary negatives it sometimes acts to
increase acutance by modifying the diffusion rate at the
edges of the image. The hardening itself can cause some
increase in acutance because of the bending of light at the
edge where the density of the gelatin is different. This
differential hardening can also cause minor image
distortion. This is of no consequence in normal photography
but precludes the use of staining Pyro developers for
photgrametry and astrophotography.
Pyro is the oldest organic developing agent known. It was
first used by F.Scott Archer C.1865 and has been in use ever
since. Pyro fell out of use in the 1920's when Metol and
Hydroquinone developers were devised. These were more
predictable and more stable. Modern Pyro formulas are
reasonably predictable but not very stable (PMK seems to be
an exception). It is not very well known that Pyro
developers also can be used for paper development to obtain
warm tones.
The stain image is not a dye but rather a very stable
pigment, probably longer lived than the silver image.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Uranium Committee" wrote in
message
...
"Jim Phelps" wrote in message
...
"Uranium Committee" wrote in
message
om...


The 'benefit' of a stained negative is the stain, which
takes the
place of silver density for papers that are sensitive
only to blue.
The stain is yellowish-green, and since these stains
block blue light,
they are seen as extra density by blue-sensitive paper.
Variable
contrast paper DOES see 'green', and so the stain DOES
NOT act as
density for VC papers.

Use and GRADED paper to get the 'benefits' of pyro. The
light source
does not matter so much. DO NOT use VC paper, because
it defeats the
whole purpose of pyro.


This information is completely wrong.

No, it's correct!

FACT: the stain is yellowish-green

FACT: the stain TRANSMITS yellowish-green and STOPS blue
light

FACT: graded paper is insensitive to green or yellow light

FACT: VC paper is sensitive to green light

CONCLUSION: the stain ADDS density as far as graded paper
is
concerned, and DOES NOT add density as far as VC paper is
concerned.

In addition, the green light that the stain allows through
softens the
contrast in the most-heavily-exposed areas, precisely the
opposite
effect that occurs when graded paper is used. Attempting
to use VC
filtration to raise the contrast simply ignores the stain
again, and
you end up fighting against the stain.
It does add density for the blue sensitive component of
variable contrast paper but less for the blue and green
sensitive layer. This has the effect of modifying the
characteristic curve of the paper. It creates what is
effecively a shoulder which flattens highlight density. This
may or may not be desirable. Some claim to get better prints
this way. It probably depends on the subject matter as much
as anything else. Essentially, the stain image acts as a
mild contrast reducing mask when used with variable contrast
paper.
When used with graded paper the stain image simply adds
to the silver image. This is not an advantage or
disadvantage although it makes measuring the effective
density of the iamge more difficult since the densitometer
must have a filter which matches the spectral response of
the printing material. I am not sure about the validity of
the idea that the stain image masks grain since it must
mimic the grain. Any diffusion of the stain away from the
grains where it is generated would affect resolution and
sharpness. This is not a common effect of Pyro development.
Pyro developers also harden or tan the gelatin in a way
which is proportional to the image density. This effect is
used to produce relief images for dye transfer and other
printing methods. In ordinary negatives it sometimes acts to
increase acutance by modifying the diffusion rate at the
edges of the image. The hardening itself can cause some
increase in acutance because of the bending of light at the
edge where the density of the gelatin is different. This
differential hardening can also cause minor image
distortion. This is of no consequence in normal photography
but precludes the use of staining Pyro developers for
photgrametry and astrophotography.
Pyro is the oldest organic developing agent known. It was
first used by F.Scott Archer C.1865 and has been in use ever
since. Pyro fell out of use in the 1920's when Metol and
Hydroquinone developers were devised. These were more
predictable and more stable. Modern Pyro formulas are
reasonably predictable but not very stable (PMK seems to be
an exception). It is not very well known that Pyro
developers also can be used for paper development to obtain
warm tones.
The stain image is not a dye but rather a very stable
pigment, probably longer lived than the silver image.


--
---
Richard Knoppow
Los Angeles, CA, USA

Uranium Committee wrote:

Szaboht wrote in message . ..


I'm not yet experienced with Pyro development, but I'm considering to give
it a try. My questions concern the enlarger lamp for pringing pyro
negatives. I read frequently that a cold light head is best for pyro
negatives (presumably due to the yellowish stain on the neg), but I have a
standard tungsten halogen lamp in my only enlarger, an Omega D2 with Super
Chromega color head. I hope to use VC paper (Forte and Kodak).

If the spectrum really must be close to that of a cold light head, is there
a filtration offset that can be dialled into on the enlarger's color head
to closely simulate the spectrum of a cold light lamp? Or, with regard to
pringint pyro negs, is the spectral difference between cold light and
tungsten halogen too small to be concerned about?

Regards,
Szabo

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The 'benefit' of a stained negative is the stain, which takes the
place of silver density for papers that are sensitive only to blue.
The stain is yellowish-green, and since these stains block blue light,
they are seen as extra density by blue-sensitive paper. Variable
contrast paper DOES see 'green', and so the stain DOES NOT act as
density for VC papers.

Use and GRADED paper to get the 'benefits' of pyro. The light source
does not matter so much. DO NOT use VC paper, because it defeats the
whole purpose of pyro.

The stain is without grain and has a nicer gradation of tone than
silver has, but again, only for graded (blue-sensitive) paper. A
negative correctly developed in pyro has a rather 'thin' silver base
which the stain supplements. If the stain were to be removed, the
silver density of a properly-developed pyro negative would be seen as
too flat and thin. It's supposed to be that way, because the stain
assists in providing enough PRINTING density to give a good print.


It is not true that VC paper defeats the purpose of pyro. VC paper with
blue or magenta filtration makes possible very versatile use of pyro.
Magenta filtration in small amounts can intensify the shadows. Pyro
makes possible negatives that can have the high contrast required for
printing-out papers like platinum and the normal contrast for use with
VC papers.

Uranium Committee wrote:

"Jim Phelps" wrote in message ...


"Uranium Committee" wrote in message
.com...


The 'benefit' of a stained negative is the stain, which takes the
place of silver density for papers that are sensitive only to blue.
The stain is yellowish-green, and since these stains block blue light,
they are seen as extra density by blue-sensitive paper. Variable
contrast paper DOES see 'green', and so the stain DOES NOT act as
density for VC papers.

Use and GRADED paper to get the 'benefits' of pyro. The light source
does not matter so much. DO NOT use VC paper, because it defeats the
whole purpose of pyro.



This information is completely wrong.



No, it's correct!

FACT: the stain is yellowish-green

FACT: the stain TRANSMITS yellowish-green and STOPS blue light

FACT: graded paper is insensitive to green or yellow light

FACT: VC paper is sensitive to green light

CONCLUSION: the stain ADDS density as far as graded paper is
concerned, and DOES NOT add density as far as VC paper is concerned.

In addition, the green light that the stain allows through softens the
contrast in the most-heavily-exposed areas, precisely the opposite
effect that occurs when graded paper is used. Attempting to use VC
filtration to raise the contrast simply ignores the stain again, and
you end up fighting against the stain.


It is quite obvious that you have not tried it, and that you have not
reasoned out the answer that you did not try. The yellow stain is a
variable density stain. You can bleach out the silver image and leave a
yellow IMAGE, not a filter layer. This yellow image can be printed on VC
paper by use of sufficient blue filtering. I have done it, and several
years ago demonstrated it in an article in Photo Techniques titled "More
Pyrotechnics" . Certainly, the yellow image is of quite low contrast
when printed on unfiltered VC paper, but it is there. The yellow part of
an unbleached pyro negative DOES increase the contrast on VC paper,
though not as much as on graded paper. If you do the following
experiment, you will see the fallacy in your reasoning. Develop any
negative in any non-staining developer to a lower than normal contrast
index. Make a straight print without filtration on VC paper. Now bleach
the negative in a rehalogenating solution such as is used in sepia
toning, and redevelop it in a pyro staining developer. Make a straight
print from this negative without filtration. Now make another print
using magenta filtration or a #3 or #4 printing filter. Report to us the
results if you dare.

"PATRICK GAINER" wrote in message ...
Uranium Committee wrote:

It is quite obvious that you have not tried it, and that you have not reasoned out the answer that you did not try.

Pat,

I believe you have hit the nail on it's head. He has NEVER tried it and is going on his flawed deductive reasoning. I believe in an older post he said something like "... no I have never used pyro but have seen prints from negatives developed in pyro."

Jim

"PATRICK GAINER" wrote in message ...
Uranium Committee wrote:

It is quite obvious that you have not tried it, and that you have not reasoned out the answer that you did not try.

Pat,

I believe you have hit the nail on it's head. He has NEVER tried it and is going on his flawed deductive reasoning. I believe in an older post he said something like "... no I have never used pyro but have seen prints from negatives developed in pyro."

Jim