Experimental Fine Grain Developer EFG-1

[Photo Engineer]

It is in my head Alan. If I can, I will formulate something. Otherwise it is lost. That is why I need help. I need to do experiments to find the optimum developer formula as I only have range values. Also, the best are beyond the range of darkroom experimentation due to some of the chemistry used.

PE

 

[Ian Grant]

That's conjecture not facts, and as emulsions changed so did these type of developers they evolved. Some Kodak developers had to be reformulated because Kodak's newer film emulsions were more prone to Dichroic fogging unlike the films they replace

Some of the Pyrocatechin developer combinations weren't possible when MCM100 was formulated, Phenidone hadn't been introduced. By the time I began serious photography in the late 1960's Johnsons had a totally different range of Meritol based developers compared to just prior to WWII.

Pyrocatechin based developers can give:

o Full and sometimes increased film speed (compared to D76)
o Very high resolution
o Excellent fine grain
0 Excellent tonal range
o Work well with ALL films

It's erroneous to assume a developer that didn't work well with a 60's generation of films will behave the same with modern films. Rodinal (and the Ilford & Kodak etc equivalents) is a developer that largely fell out of use as grain was an issue with 60's emulsions but it regained popularity as it give excellent fine grain and acutance with modern emulsions. Rodinal and Tmax100 or Afa AP/APX100 gives far better results all round compared to the same films in D76, much of this is because a modern film's grain is more an inherent function of the emulsion itself and less effected by the developer itself.

So there's still avenues to follow with Pyrocatechin based developers, I've never suggested that older formulae themselves are the answer rather that they are pointers to avenues not explored.

A developer like Sandy King's Pyrocat HD which is very widely used is actually very close to a 1940's Ilford research formula (Pyrocatechin instead of Pyrogallol), the 1943 Dr Eugene Mayer Pyrocatechin Fine Grain developer so it's wrong to assume there's not potential in this area.

Ian

Among the reasons why developers like MCM100 are no longer used are

o they didn't work as claimed;
o improvments in emulsion technolgy made their use unnecessary;
o they did not work well with modern films;
o they caused a severe degradation in resolution;
o they caused a loss in film speed;
o they were toxic.

 

[Photo Engineer]

Much more is known about development than is published. Much of it remains Kodak confidential material. But, OTOH, based on what I have seen, all points of view have validity. Many old developers will work, but are better if re-formulated for current films. We have seen examples here but many here do experiments that are not designed to show the optimum position correctly having mismatched speeds or contrasts or both. And, we always seem to lack curves which would essentially show these problems clearly.

I can say that there are modern developers possible that certainly outdo old developers and the proof is in some of the newer formulas. And, at the same time we can see some old developers that work and others that require slight reformulation.

PE

 

[c6h6o3]

It looks to me like Ron's EFG-1 has slightly more grain than Xtol, but higher accutance. That's why I would choose it over Xtol.

 

[bwrules]

If the pictures are all well focused, it looks as though EFG has higher resolution than Xtol. Does higher acutance mean higher resolution? Or they don't necessarily go together? Thanks.

 

[Keith Tapscott.]

Pyrocatechin based developers can give:

o Full and sometimes increased film speed (compared to D76)
o Very high resolution
o Excellent fine grain
0 Excellent tonal range
o Work well with ALL films



So there's still avenues to follow with Pyrocatechin based developers, I've never suggested that older formulae themselves are the answer rather that they are pointers to avenues not explored.

A developer like Sandy King's Pyrocat HD which is very widely used is actually very close to a 1940's Ilford research formula (Pyrocatechin instead of Pyrogallol), the 1943 Dr Eugene Mayer Pyrocatechin Fine Grain developer so it's wrong to assume there's not potential in this area.

Ian

I have yet to try Pyrocat.

 

[bwrules]

Also see Hypercat http://hypercatacutancedeveloper.blogspot.com/

 

[Gerald C Koch]

Regarding Hypercat, PMK, Pyrocat and most current and past Pyro or Catechol formulations, they are not especially fine grained, even with their tanning/staining action. Only my personal view but I don't like them with small format film.

You are quite correct. The stain that they produce is a dye cloud which has migrated from each grain that produced it. This not only increases the granularity but also blurs the edges of each grain. This latter effect reduces the acutance of the image. These two problems are reduced somewhat by the fact that the image is formed of silver and stain. This permits development to be stopped before the silver grains become as large as those from a conventional developer. You can see these things if you look at a stain image with a microscope. Such developers are not suitable for small formats.

 

[bwrules]

That's odd. The HP5+ negatives I have which I developed in 510-pyro when I was trying out pyro are much finer grained than non-510 pyro negs. This is probably due to stain masking. This is 120 size. Not sure I like the look of the resulting prints on VC paper. Hypercat would probably give a far larger grain though.

What happens if one develops to high contrast and then bleaches out the stain so the resulting neg is normal contrast?

 

[Photo Engineer]

Well, using VC paper with stained negatives is not a good idea IMHO. The color acts as a contrast filter leaving you with the problem of adjusting the contrast filter for every negative to get contrast centered. Each "center" will vary with stain type and level.

I must add that the micro edges caused by the pyro will increase sharpness at edges. The relief image (or micro edges) which form, are caused by tanning and vary with the stain level and developing agent type.

PE

 

[Ian Grant]

I had always read Pyro naturally produced relatively high acutance negatives. So I'm not sure what to make of Gerald's comment regarding the blurred grain edges. That's news to me.

Apparent graininess of a print is not the same as measured film grain, a film can appear to have fine grain when measured but prints may appear grainier, something Kodak were well aware of.

The reverse is equally true as well, measured film grain of a staining developer/film combination may sometimes appear larger but the prints appear finer grained because of the stain which migrates into the gelatin around the silver grains.

Ian

 

[Gerald C Koch]

If you look at a stain image with a microscope you will see each silver grain surrounded by a stain halo. The diameter of the halo may be several times the diameter of the silver grain. The diameter is effected by how rapidly the oxidation products of the developer are destroyed by a reducing agent such as sulfite. The higher the sulfite concentration the smaller the halo. This halo increases the size of each grain. If you bleach out the silver image the resulting stain image will not appear as sharp.

 

[Gerald C Koch]

Ian is quite correct. Let me add a quote from Glafkides "Photographic Chemistry", "A fine-grain developer cannot retore the loss of definition caused by a coarse-grained emulsion."

 

[Gerald C Koch]

Acutance depends on how the human eye perceives objects. It is an optical illusion. An object with a sharp change in optical density at the edge will appear sharper than a smaller object with a smoother change in edge density. A black square on a white background will appear sharper than an identical light gray square. But put the gray square on a black background and it will appear sharp.

 

[Photo Engineer]

The blurred image is offset by the relief image created by tanning. Jerry is correct in all instances.

PE

 

[bwrules]

I don't know. I have no use for Perceptol and the like. I actually wish TMY-2 had more acutance in Xtol.