Can You Make A High Acutance Developer Using Phenidone?

[psvensson]

I've mixed a lot of different developer with metol and phenidone, and I've found in every case that metol gives a crisper, sharper look, at the expense of speed. I don't believe I've seen any real edge effects - it's more about the grain size and dispersion, I think.

 

[gainer]

Densitometer traces.

Patrick, the line widths are as indicated on the traces. They were exposed at exactly that width. They are made to roughly simulate a given object at 35mm, 120 and 4x5 format sizes.

PE

Yes, but where are the marks that would tell us where those actual edges were with respect to the densitometer traces? I would also be interested in similar measurements of a number of parallel lines, as in a resolution target.

 

[Photo Engineer]

Patrick;

Unfortunately, the reference marker is not shown in the article. Sorry. The measurment of a number of parallel lines is normally done for MTF plots. This is entirely different.

The entire sequence includes exposures to X-ray, white light, and positive and negative parallel lines. This gives values for sharpness, resolution and turbidity. The positive and negative images also give a measure of fill in and bloom of the image with respect to edge effects and scatter.

It is not a simple test. And then you do this over a set of lines to get micro vs macro contrast as shown in the right photo above to measure the effectiveness of the image at different magnifications.

PE

 

[gainer]

My confusion about what the densitometer traces prove is compounded by the fact that I can find no measurement of the traces that shows the 1:10:100 ratios. I have to tell you that the traces look as if they had been drawn freehand. They bend slightly backward in a couple of places. The last time I saw anything like this was at NACA. We used to record time histories of flight parameters on oscillograph film. In reproduction by litho film and developer, the trace would occasionally drop out. This particular time, the retouching was left in the hands of a photo technician, who etched the trace, I guess, so that it looked pleasing. Anyway, a part of it went backward in time. Fortunately, the editorial committee of engineers caught it before it got published. From that time on, all necessary retouching was done by aeronautical engineers with reference to the original data. We all had etching knives and spotting brushes in our desks from then on.

 

[Photo Engineer]

These are real traces from real data. What you see is noise in the film due to grain and other factors.

The traces done at different exposures (just one of the set is shown on the left) were plotted as a series of increasing density in the figures on the right as is noted in the legends at the bottom. This shows that as line size goes down, contrast goes up. It also shows that measurement of macro contrast is sometimes misleading. The contrast would continue to decrease as the size of the chart (or slit) increased.

This is not untypical in films, and is always overlooked here in posts. No one has the proper equipment, the background, nor the inclination to design a film / developer composition this way. It is usually done qualitatively when it should be done both qualitatively and quantitatively.

PE

 

[gainer]

Maybe so, but it is still impossible to have two or more different densities at the same point on the emulsion. How would one see the lesser without looking through the greater? The several densities would have to add, just as if there were several layers of emulsion or film. Anyway, it is just another humerous example of a typo.

How can we mess with the edge sharpness of an image without messing with the spacing between two images? The only way I can imagine is to make the image on film as true as possible, without the artifacts that cause the coveted edge effects. Perfection is not possible in our lenses. Can we make up for the imperfections by photochemical means? I think not. We can make an extended edge appear sharper, but we chance losing resolution in fine detail. There is the possibility, of course, of using one process when fine detail is important, and another when larger sharply defined forms are important. Oh, well. To each his own.

 

[Roger Hicks]

Can we make up for the imperfections by photochemical means? I think not.

Seconded. Or of course we can apply 'Sharpen' in Photoshop, with similar success.

 

[Alan Johnson]

As I was curious to see the effect of carbonate alkali on acutance I did the line test mentioned in my post no. 11 on the developer I called FX-1 copy:
Phenidone 0.1g, sodium ascorbate 5g, sodium carbonate 2.5g, water to 1L.
Plus-X was stand developed in FX-1 copy diluted 1+3 90min 68F and a 10x enlargement of the edge made.
It is possible to put the lines obtained with different developers in order of intensity.From this and other tests, developer acutance in order of increasing acutance was:
PC-TEA< FX-1 copy< Pyrocat HD< Crawley's FX-1.
I concluded that carbonate alkali in PC developers without sulfite gives more grain and film speed but not much increase in acutance compared to PC-TEA and acutance is not particularly high.