Edge efects with Pyrocat-HD

Dave Krueger · Dec 28, 2006

I conducted an experiment wherein I developed two identical 4x5 sheets of Adox PL100 as follows:

Sheet #1
distilled water presoak = 2 minutes (continuous agitation)
dilution = 1.5:1:200 (distilled water)
Extreme minimal agitation for an hour at 68F. (1.5 minute initial rotary agitation with 2 inversions at 15, 30, and 45 minutes)
4 minute fix in non-hardening rapid fix (continuous agitation)

Sheet #2
distilled water presoak = 1 minutes (continuous agitation)
dilution = 1:1:100 (distilled water)
Rotary (continuous) agitation for 11 minutes at 69F.
4 minute fix in non-hardening rapid fix (continuous agitation)

The two negatives are remarkably similar considering the difference in processing.

My question is this: I assume there should be edge effects in the negative done with minimal agitation. At what magnification (enlargement size) are those edge effects most likely to be apparent?

I'd be grateful for any comments.

sanking · Dec 28, 2006

Dave Krueger said:
I conducted an experiment wherein I developed two identical 4x5 sheets of Adox PL100 as follows:

Sheet #1
distilled water presoak = 2 minutes (continuous agitation)
dilution = 1.5:1:200 (distilled water)
Extreme minimal agitation for an hour at 68F. (1.5 minute initial rotary agitation with 2 inversions at 15, 30, and 45 minutes)
4 minute fix in non-hardening rapid fix (continuous agitation)

Sheet #2
distilled water presoak = 1 minutes (continuous agitation)
dilution = 1:1:100 (distilled water)
Rotary (continuous) agitation for 11 minutes at 69F.
4 minute fix in non-hardening rapid fix (continuous agitation)

The two negatives are remarkably similar considering the difference in processing.

My question is this: I assume there should be edge effects in the negative done with minimal agitation. At what magnification (enlargement size) are those edge effects most likely to be apparent?

I'd be grateful for any comments.

First, I am not surprised that the negaive look similar. If they were developed for the same CI they should. However, to compare how they print adjust the exposure for contrast and print a small part of the two negatives at about 4X, then compare the difference. You should see greater apparent sharpness with the negative developed in minimal agitation. If you don't, try semi-stand with just iniital agitation and one more at about the half-way point of development.

Sandy King

Dave Krueger · Dec 29, 2006

sanking said:
First, I am not surprised that the negaive look similar. If they were developed for the same CI they should. However, to compare how they print adjust the exposure for contrast and print a small part of the two negatives at about 4X, then compare the difference. You should see greater apparent sharpness with the negative developed in minimal agitation. If you don't, try semi-stand with just iniital agitation and one more at about the half-way point of development.

Sandy King

OKie-dokie. I made an 8x10, but I was thinking that might not be large enough to spot the differences. I will make an 8x10 crop from a 16x20 and see if the difference is more noticeable. My primary exhibit size is 16x20, so that is probably a better choice anyway.

The intent was to make the negatives look the same in terms of density and contrast, so that I could focus on edge effects. I just didn't think they would be THAT similar especially on a first attempt. In the past, anytime I've left a negative in developer for an hour, it was by accident and I generally didn't expect a good result. haha!

I'm new to minimal and semi-stand agitation techniques. I'm not even sure of the Adox was the best film to use for edge effects testing, but I've been using it in my experiments with different devlopers lately, so I have a broader frame of reference with that film than most others.

Tom Hoskinson · Dec 29, 2006

Adox PL100 responds very well to Stand and Semi-Stand development in Pyrocat. The resulting edge effects should be obvious in an 8x10 negative or contact print.

Dave Krueger · Dec 29, 2006

Tom Hoskinson said:
Adox PL100 responds very well to Stand and Semi-Stand development in Pyrocat. The resulting edge effects should be obvious in an 8x10 negative or contact print.

I have two more sheets exposed exactly the same as the ones I used for these tests, so I can try semi-stand and see if that enhances the effect. Sounds like something to do over the long weekend.

Any suggestion on how I should modify my developing time to do semi-stand or stand? Should I change the dilution?

Tom Hoskinson · Dec 29, 2006

Dave,here is my procedure For Semi-Stand development in a plastic tank:

Developer dilution = 1:1:100 (with 70F distilled or deionized water)

1.Distilled or Deionized 70F water presoak for 5 minutes (with ocasional agitation by gentle torus inversion), then dump presoak water.

2. Fill tank with 70F developer and agitate initially for 30 seconds by gentle torus inversion at 70 F.

2. Then stand for 9 minutes with no agitation AND:

3. Agitate for 30 seconds by gentle torus inversion

4. Stand for 9 minutes with no agitation, then dump developer.

5. Rinse with 70F water and dump

6. Fix in non-hardening rapid fix at 70F (with continuous agitation)

7. Wash in 70F water and dry

gainer · Dec 29, 2006

Perhaps it is not well known that the eye of the observer has its own edge effect. You can see it at the boundary of a black area with a very light gray area. The gray is lighter than that a short distance rfrom the black. Many time I have seen these edge effects go away when the edge is viewed with a loupe.

noseoil · Dec 30, 2006

Dave, what was your SBR for the shot? If you can tell us what type of contrast you were working with and the type of scene, I can suggest a time. Need a bit more information to give a decent time. It is with a regular silver paper, right? Best, tim

Dave Krueger · Dec 30, 2006

noseoil said:
Dave, what was your SBR for the shot? If you can tell us what type of contrast you were working with and the type of scene, I can suggest a time. Need a bit more information to give a decent time. It is with a regular silver paper, right? Best, tim

I don't know what the SBR was, but here is the print:

http://www.kruegerphoto.com/edgetest.jpg

Also, if you're interested, here are small (~ 1MB) uncompressed BMPs of a small section of the scene at 1200 dpi.

http://www.kruegerphoto.com/edgetest_sm1.bmp <-- minimal agitation
http://www.kruegerphoto.com/edgetest_sm2.bmp <-- rotary agitation

The two prints are not identical. The first print is slightly darker and a tiny bit more contrast. They are both printed with the same VC filtration (20M), but the first one is exposed under the enlarger for a couple seconds more than the second (16 sec vs 14 sec).

There is no sharpening or other tweaks to these. I didn't even clean off the dust.

Jim Noel · Dec 30, 2006

On my monitor, I would choose the rotary agitation negative. The print shows the lines in the hinge which are not distinguishable in the minimal agitation negative.

Dave Krueger · Dec 30, 2006

noseoil said:
Dave, what was your SBR for the shot? If you can tell us what type of contrast you were working with and the type of scene, I can suggest a time. Need a bit more information to give a decent time. It is with a regular silver paper, right? Best, tim

Actually, I'm not very knowledgeable on that topic. I know there are a lot of subjective and subconscious factors relative to how a viewer perceives an image. But, my audience consists primarily of myself and I'm the type of guy who presses his nose right up against the glass when viewing an exhibit. If there are going to be edge effects, I want to be able to see them on the print.

It might also be that there are edge effects and I'm just not seeing them. This is mostly an exercise in determining whether , in my own subjective appraisal, the benefits of reduced agitation techniques yield an improvement in the prints that make the technique worth the extra trouble (or extra chemicals). If the edge effects were too pronounced, I'd probably reject it for being unnatural, but if they're too subtle, it might not be worth the trouble. Unfortunately, I don't have a lot of time for photography, so I don't want to invest a lot of time investigating the craft instead of doing the art.

gainer · Dec 30, 2006

If you are expecting the same result from developer edge effects that you might get from unsharp masking, it won't happen. You are most likely to see the edge effects you are looking for when the image is sharp to begin with. These images look a little fuzzy. It doesn't look like digital sampling artifices either.

The Mackie lines (I believe they are called) depend on an abrupt change in exposure across the line. Otherwise, the developer products from the heavily exposed area are spread over a gradually decreasing exposure before they reach the minimally exposed area.

sanking · Dec 30, 2006

gainer said:
If you are expecting the same result from developer edge effects that you might get from unsharp masking, it won't happen. You are most likely to see the edge effects you are looking for when the image is sharp to begin with. These images look a little fuzzy. It doesn't look like digital sampling artifices either.

The Mackie lines (I believe they are called) depend on an abrupt change in exposure across the line. Otherwise, the developer products from the heavily exposed area are spread over a gradually decreasing exposure before they reach the minimally exposed area.

Pat is right in that the type of edge effects you get with adjacency effectds is not nearly as obvious as what you see with unsharp masking, either in the darkroom or with manipulation in Photoshop. Also, in my expereince he is also right in that the most obvious difference will be see in subjects have a lot of detail where there is a sharp line between shadow and highlight areas.

On the other hand, Steve Sherman has gotten very good results wih semi-stand development iin shooting subjects of low contrast, though I guess the type of edge effects with this type of subject would be somewhat different than what we see in the more typical scenes.

Sandy

gainer · Dec 30, 2006

Edge effects are in that wide category of things we attribute sharpness to, often without a proper basis of comparison. If I had my druthers, I druther have true sharpness, the way I saw things when I was young, than any kind of artificial sharpening by masking, developing or computer tricks. The trouble is, it is likely to be with us always simply because of the nature of things. I have some glass plate negatives made by my grandfather 100 years ago that prove that statement to my satisfaction. I certainly don't want anyone looking at one of my pictures and not finding anything better to say than "My, what wonderful edge effects."

Tom Duffy · Dec 30, 2006

Maybe a little off topic, but I tried a variety of developers (xtol, d76, rodinal, hc110 and pyrocat) in a jobo several years ago, including rodinal at 1:50. I developed 5x7 negs and printed to 10x13. The sharpest prints I got were with pyrocat hd. This held true for PL100 and Tri-X. Rotary agitation probably didn't help the Rodinal/Tri-x combination.

Since then I've standardized on Tri-x and pyrocat in a jobo. Best sharpness in a rotary processor. For me (others think differently of course) , why spend inordinate amounts of time doing semi-stand development when a rotary gives more even results, anyway?

Steve Sherman · Dec 30, 2006

Micro contrast total control

I've been watching this thread and still wonder why everyone's interest lies in just the sharpness aspect of Reduced Agitation Development.

See this link which I started sometime ago which deals with the endless Creative possibilities with this type film development.

(there was a url link here which no longer exists)

sanking · Dec 30, 2006

gainer said:
Edge effects are in that wide category of things we attribute sharpness to, often without a proper basis of comparison. If I had my druthers, I druther have true sharpness, the way I saw things when I was young, than any kind of artificial sharpening by masking, developing or computer tricks. The trouble is, it is likely to be with us always simply because of the nature of things. I have some glass plate negatives made by my grandfather 100 years ago that prove that statement to my satisfaction. I certainly don't want anyone looking at one of my pictures and not finding anything better to say than "My, what wonderful edge effects."

Pat,

There is no such thing as "true" sharpness. Sharpness is a somewhat subjective evaluation that results from an attempt to quanitify a number of other somewhat subjective criteria, such as accutance, resolution, micro and macro contrast, etc.

Sandy

Donald Miller · Dec 30, 2006

gainer said:
Edge effects are in that wide category of things we attribute sharpness to, often without a proper basis of comparison. If I had my druthers, I druther have true sharpness, the way I saw things when I was young, than any kind of artificial sharpening by masking, developing or computer tricks. The trouble is, it is likely to be with us always simply because of the nature of things. I have some glass plate negatives made by my grandfather 100 years ago that prove that statement to my satisfaction. I certainly don't want anyone looking at one of my pictures and not finding anything better to say than "My, what wonderful edge effects."

Pat with all due respect, how much "artificial sharpening" have you personally done? Do you have the means to do precise masking at the printing stage? What adaptations have you made or had made to your enlarging equipment to allow you to do this "artificial sharpening"? Who performed these modifications and what specific modifications to allow highly precise masking were performed. I get questions all the time about masking. Perhaps with your self professed personal experience I could just direct these enquiries to you.

If you do not have the means to perform this "artificial sharpening", on what basis are you making your rather broad statements?

I think that there are a number of us here who would enjoy hearing about your verifiable personal experience with this matter.

gainer · Dec 31, 2006

It's hard to ignore that kind of insult, but I will try. All of us have seen the work of Howard Bond displayed in Photo Techniques.

I have to go now. Later

gainer · Dec 31, 2006

I am back.
I was expressing a personal opinion, not preaching the gospel. Have I ever done the unsharp masking in the darkroom? No, and I never calimed to have. My desire to do so has been tempered by what I have seen. There are photos that look as if they had been pasted up from cutouts. I don't want mine to look that way.
I have had experience with the computerized version, and I don't much like that either. I am sure there are those photos that can profit from judicious use of unsharp masking.
I don't understand the complaint. I tried to say that, if possible, I would avoid artificial sharpening. When I do use it, I want it to be unobtrusive, not the center of attention. There is no harm in creating a photo in which the effect is an integral part of the artistic effect. It is just not my dish.

My enlarging equipment includes an easel densitometer that I designed and built myself that allows me to switch between reading Zones and projection densities. I could use it to set the exposure for an unsharp mask.

I do know for a fact that the effect of an unsharp mask is not the same as the edge effect possible with most developers.

Photo Engineer · Dec 31, 2006

I'll have to agree with Patrick here. An unsharp mask is not the same as edge effects.

In addition, edge effects or unsharp masks are difficult to judge or comment on unless you have comparisons without these effects to make the judgement with.

Also, these effects are dependant on magnification and viewing distance, two subjective factors to consider. Contrast of the image is another.

I have mentioned elsewhere and article by M. Kriss in which he describes edge effects and shows sensitiometric curves of 3 different magnifications. Basically, good edge effects increase contrast as size of the object decreases thereby making contrast roughly the same as magnification increases.

This means that a 35mm film H&D curve may equal a 4x5 film H&D curve, but the micro contrast of the 35mm film is effectively higher than that of the 4x5 film. The standard H&D curve only measures macro contrast, but edge effects are measured by micro contrast.

This subject is totally ignored in most literature and most all posts here on APUG as it is 'too technical' but it is core to the problem, and core to getting good results.

PE

Donald Miller · Dec 31, 2006

The point that I was attempting to address here is that there were some rather broad statements made about "artificial sharpening". I find that, for myself, to view a magazine reproduction is a poor handmaiden to viewing the actual print or a comparison of two prints, for that matter. To make statements based upon a magazine or other reproduction seems to be making them from an ill informed basis.

I agree that unsharp masking...or any of the other forms of sharp masking is not the same as edge effects. I have never stated that they were the same nor would I.

There is a heck of a lot more to masking than the practice identified as unsharp masking. Sharp masking requires modifications to most enlarging equipment with which I am aware. These modifications are required for precise registration of the camera negative and mask (s).

Donald Miller · Dec 31, 2006

Quote:"This means that a 35mm film H&D curve may equal a 4x5 film H&D curve, but the micro contrast of the 35mm film is effectively higher than that of the 4x5 film.

Are you sure of your statement in regard to the micro contrast comparison of film formats? Why do larger format prints have the capability to evidence higher micro contrast than smaller format prints?

Photo Engineer · Dec 31, 2006

Micro vs Macro Contrast - Edge Effects

The enclosed graphical data is reproduced here with the permission of Michael A. Kriss, author of the definitive article on imaging structure in the SPSE publication "Color: Theory and Imaging Systems"

It shows the edge effects on density of 3 different line widths. As line width decreases, micro contrast (density of lines with different exposures) increases, therefore the effective contrast goes up as format decreases for an identical photo. This is shown in the contrast changes in the second plot.

PE

Photo Engineer · Dec 31, 2006

The bottom line is this. Edge effects are not good edge effects unless they do what is shown in the above post. Otherwise, the results will vary with magnification, leading to poor results, or what one wag described as "an optical delusion".

PE

Edge efects with Pyrocat-HD

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