xosni

Ilford products are much better than Kodak's in general.

What is so special about Tmax developer that makes it the best suited for Tmax films? Why isn't there a formula for Tmax from scratch? Is it a kodak secret or just an innovative idea from the sales department?

someone sent me this thru the usenet:

Xosni wrote me that he is looking for improved sharpness. I am

posting an answer here as well as to him via e-mail because I think it

may be of general interest.

The effect of sulfite in a developer is subject to some

misundersanding. In fact, sulfite has a rather complex releationship

with the developing agents and the development process, some of the

confusion comes from this complexity.

Sulfite does two major things: one, it acts to protect the

developing agent from oxidation; two, it acts as a solvent for the

undeveloped silver halide.

The absorption of oxygen by the sulfite has two effects. One is that

it protects the developing agents from oxidation by the air.

Developing agents are reducers, their purpose is to absorb oxygen from

the exposed silver halide grains and convert them into metallic

silver. Oxygen from the air, and oxygen dissolved in the solution

competes with the oxygen in the developing silver grains for the

reducer and will quickly ruin it if its not protected by sulfite or

some other oxygen absorber.

Beside protecting the reducing agent from atmospheric oxygen the

sulfite acts to regenerate the reaction products of development. It is

here that the amount of sulfite can affect the apparent sharpness of

the image.

When a develping agent (reducing agent) develops exposed silver it

produces both the silver and some other substances as a result of the

chemical reaction. These substances can either retard or accelerate

development, depending on the developing agent. Metol reaction

products tend to restrain development, those from Hydroquinone tend to

accelerate it.

This effect takes place in a very small area around the developing

silver halide crystals. The reaction products can move within the

emulsion only by diffusion. Those which move toward the outside can be

removed by agitation but those which move sideways in the emulsion

have an effect on the development nearby. At the border of a high

density and low density area the effect of these reaction products is

to modify the rate of devlopment in a very narrow area near the

border. This results in a line on each side of the division in

densities. The direction of the density of the line, and its degree,

depend on the type of reducing agent or combination of agents, on the

amount of emulsion swelling, and on the amount of sulfite. Sulfite

tends to keep these effect from happening.

It turns out that the human eye interprets high contrast at a

deviding line between dark and bright as sharpness. In film this is

called acutance. It is different from resolution. It has been

demonstrated that a high actance image looks sharper than one with

lower actance (or edge contrast) but higher resolution. Its an optical

illusion. A tight, sharp grain pattern also gives the illusion of

sharpness.

Low sulfite developers tend to produce stronger edge effects and

thus, greater acutance. Since the effect is fixed in scale it is less

visible as the silze of the format gets larger.

Sulfite also acts in a couple of other ways.

It is a salt and tends to prevent emulsion swelling. This can have a

effect on grain since the harder gelatin makes it more difficult for

nearby grains of silver to migrate toward each other causing clumping.

It is groups of grains which we see as film grain. The individual

grains are submicroscopic and are investigated using an electron or

proton microscope.

The solvent action of sulfite also has an effect on grain, but not

by dissolving away a part of the developed grain (although very large

amounts of sulfite can do this a little). The sulfite etches the

surface of the halide grains. Moderate amounts of sulfite etch enough

halide to expose sensitivity specks benieth the surface, making them

developable, and increasing effective film speed. Too much sulfite, or

the use of more powerful solvents, like thiocyanate, can etch right

past some of these specks, destroying part of the latent image and

lowering the speed.

The sulfite also affects the morphology, or shape, of the developing

silver grains. Very low sulfite developers, or experimental ones

without sulfite, develop rounded silver crystals, about the same shape

as the undeveloped crystals. This is also true of solution physical

development.

Higher sulfite developers result in "filimentary" silver. Electron

micrographs of these grains look like tufts of steel wool. The

filimentary silver tends to have greater covering power than the sharp

crystals so the effect is fewer holes for light to get through when

many grains are in an area of the film, as in dense areas. The effect

of the very small silver grains is somewhat statistical in nature,

remember that _visible_ grain is the result of many submicroscopic

grains. The solvent effect of the sulfite has the effect of bluring

out the effect of graininess. This has no effect on sharpness because

it is on too small a scale.

Sulfite also encourages physical devleopment. The halide dissolved

by the sulfite can be deposited on growing silver crystals by the

devloper, increasing their covering power. Filimentary crystals are

typical of chemical development, sharp edged crystals of physical

development. Nearly all practical developers result in a combination

of the two types.

Excessive physical development can have the effect of bluring edges

and can reduce actual resolution. It takes a lot of physical

devlopment to get this effect, even strongly solvent developers like

Kodak Microdol-X full strength do not affect resolution when compared

to a lower sulfite deeveloper, like Rodinal.

Because of the effect on the latent image high sulfite developers

which are not very active will loose some film speed when used at full

strength but gain it back when diluted. They will also get grainier

because the anti-swelling effect of the sulfite is lost.

Low sulfite developers may be the opposite, they will become

somewhat less grainy and may loose some film speed as they are

diluted. Rodinal is an example. Rodinal is very high pH since it uses

potassium hydroxide as the accelerator. Hydroxide has little buffering

power so the pH becomes lower as the dilution incrases reducing

emulsion swelling and grain. Probably Rodinal with sulfite added acts

more like a high sulfite developer.

In any case, it is not the solvent power of sulfite which results in

some high sulfite developers making somewhat unsharp images but rather

the reduction of edge effects. Since these are due to the antioxidant

property of the sulfite any other anti-oxidant will have similar

effects.

Boy, this has turned out to be a long answer to a short question:-)"

"

But what are the difference between ABC pyro, PMK & other formulas of

pyro?

I agree with Dan that you have to control the contrast at the film

level. I expose at 100 & develop for 800! yes! You will get a washed

out look (not with TMAX tho) that canbe realy cool with portraits.

Constant agitatio will kill the acutance. Just over expose & over

develop!

I have two questions regarding pyro:

What are the brand names of the available-if any- commercial pyro formulas? (in europe)

 

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How do you compare the acutance it produces with high definition developers? I read it is capable of producing high degree of acutance esp. in highlights.

 

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thanks

I did it!

Techinal Pan in FX-1 1:1 for 50 min @ 29ºC; EI 25

Resulats are great (they seem so as I didn't print any yet). normal

contrast, high acutance, great tonality.

 

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I also tried it with Xtol 1:4 & techinal Pan for 60 min. @ 29ºc. It

came out overdeveloped but still promising. I think there is some

real spead gain here; we'll see.

Distilled water, is it a must? What if i add a pinch of sodium

sulfite instead?

What films did you try it with?

 

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thanks

I want information about this technique.

I just tried developing Technical pan in FX-1 using the stand developing method. It was 1:1 dilution for 10 minutes @ 29º C. I only agitated for 30 sec at the begining then non. Tho the negative came out extremely underdeveloped it still look encouraging. So next time I'm gonna try it in an undiluted FX-1 developer but... for how long? And should I give it any tank inversions in the middle of this long period?

 

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thanks

What about APX? I thought it is an old technology film like PX & TX?

But you can't do a search?

So temperature & time are not reciprocal, right?

I do develop in high temperature during the summer (30ºC - I live in

Cairo- egypt) I don't realy see a tangible difference.

What is the effect exactly of changing the developer temperature much above the recomended (&compesating with shortening the development times)? It seems that there is no consensus regarding this point. Some say that there is no difference with newer developers, however with older ones the developer may act totally different in different developers?

Is there any archive for this mailing list? (B&W developing & processing)

I recently bought a pack of dk-50; I wonder if anybody use it still. Some say it's identical to Tmax, but I never realy liked tmax; it is not crisp enough I believe, meanwhile Dk-50 is supposed to yield higher sharpness & grain. How do you rate this developer regarding the edge sharpness & tonality? And how do you compare it with other developers like Tmax & rodinal.

I also heard that these old devlopers behave differently at different temperatures- I develop at 28-30ºC; what difference shall I expect?

 

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Regards

I was looking all over the web for some info regarding russian B&W films & paper to no avail. The reason is that my local supplier has some material that neither him nor me know nothing about! (some are labled only in russian). Any of the russians here can help?

 

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thanks

I found an old pack of "Kodaline industrial paper". What the hell is that?

Transparancy?

It's written "non-ortho" on the cover, with code "C"

How to develop it? in normal B&W paper developer or in lith one?

 

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thanks

I don't agree.

One more important thing is the uniformity of the grain. Tmz in a

coarse grain developer will yield a very ununiform grain clumps. It's

ugly. If you want grain you can try Kodak recording(if still there

any) or forte 400 overdeveloped in rodinal, DK-50, Fx-1, or D-19-

depending on the look you want.

You can also presoak the film in an alkaline solution of sodium

carbonate or even potassium hydroxide prior to developing.

One more important thing: paper grain. print of cold -tone high

contrast paper. I use Dokulith for developing paper with grain (this

is not infectious development)

 

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Xosnib

The darkening won't affect the results.

But I was wondering how to augment the edgw effect? Lower dilutions

or higher ones? cos rodinal tends to give bigger grain with higher

concentration- contrary to "normal" developers!?

Agitation every one minutes seems to work better, yes. The

recomended agitation every 30 seconds seems to spoil the edge effect.

This technique is called acceleration or maximization. I did it

before, and tho I was not very happy with the results, this technique

can yield very impressive vivid high contrast colors when done with a

slide film but the first development is realy critical & you have to

experiment alot to get the best timing & developer.

 

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I'd like to hear the feedback

Yes I meant a separate bleach bath.E-6 bleach will do.

I use tetenal, it has a sepaeate bleach bath.

A black & white negative is useless, it's gonna look very dull, too

soft. I believe you are gonna be happier with the color negative.

I like to rate it 1000-1600 & develop acccording to the contrast I

want. I like overdeveloping, esp. in an acutance developer like

rodinal. With super high speed films you don't have to listen to what

they say about the film speed & development times, they are just a

starting point. So, shoot at 1600 & develop at 3200.

You should bleach (c-41 bleach will work), and then develop in c-41-

don't push process- to get a high contrast, little more grainy color

negative.

You can redevelop it in B&W developer-after the bleach of course- but

you will get a dull B&W negative anyways. If you have used a wetting

agent then you have to rinse in heavily for 20 min.

I used PXP in rodinal 1+50 & I didn't find any pronounced edge effect

(?!). I don't know but if you want midtones stay away from rodinal.

rodinal edge effect is more pronounced with faster films. For me slow

films like Verichrome, PXP & PanF plus work better with d-76 1:3 &

Xtol 1:1 or stock. The beautiful tonal gradation of these films get

lost with rodinal. These films are acutance films anyways, not like

Tmax.

I recently made my FX-1 from scratch. The edge effect is more

pronounced & the grain look "different", but still I need more

experimentation to tell you my final opinion about it.

Hey Ed,

Acutance means, simply, edge sharpness.