Edge effect and acutance

Hi all,

As far as I can understand Tmax 400 is a film with edge effect. If I get this right this is what I see when (ie) branches stand out on a landscape image compared to a film like Ortho+.

Are there other films available in 8x10 that shares these characteristics when developed in a regular developer (Xtol/ID-11)?

Cheers
Peter

There used to be films that showed edge effect like old Tri-X in Beutler as in this book by R.Henry:
The edge effect was much reduced when the iodide content of films was increased when they got their sharpness by other means than edge effect, though some edge effect remains.
I suggest new Tri-X or HP5+ as worth trying. The effect will be greater in an acutance developer than in a solvent developer.

HP5 has good acutane in xtol 1+1.

In my experience, the appearance of edge effects (and related acutance) is dependent not only on the film stock, but also on the developer used and development technique. For example, I shoot a lot of 8x10 Foma 100. When I develop it using, say, Xtol in Expert Drums on my Jobo, the final negative has all the appearance of any "normal" negative. However, when I develop that same film in Pyrocat-HD using a minimal agitation technique, if you hold it such that light glances across the emulsion side it appears etched. Based on what I know about edge effects, I'm not totally sure that's what I'm seeing but it's very apparent, nonetheless, and the prints do look different to my eyes.

It's not so much the film you choose, but the developer. Select a developer known for enhancing edge effects. Pyrocat HD is top of the list.

I agree with others. It’s more about the developer. Use a non-solvent developer like Ilfosol 3 or Rodinal. Or a solvent developer like ID-11 diluted 1:1 to 1:3. Dont agitate more than once a minute. Even less agitation than that will give even more sharpness. Every other minute, semi stand etc.

Accutane is an acne medication

Andrew O'Neill said:

HP5 has good accutane in xtol 1+1.

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If you're shooting 8x10, you're going to need to make some big prints to see the effects described. Although the advice already posted makes sense.

Acutance is the actual edge sharpness at the boundary between two densities. It is the steepness (slope) of the transition.

Edge effects have to do with contrast at those boundaries (ie the total density difference). The greater the edge effects the greater the contrast at abrupt boundaries. This is what unsharp masking does (in digital editing also). It can enhance the perception of sharpness (which has to do with several things including acutance and edge effects).

Milpool said:

Accutane is an acne medication

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Corrected. Thanks. I'll use D23 so I don't need no accutance

Acutance and edge effects are two different things. Acutance or sharpness is baked into the film to a large extent with speed and grain size and then "preserved" by using non-solvent developers (solvent developers with lots of sulfite soften the grain but hurt the acutance a bit).

Edge effects, as in Mackie lines, are developer artifacts. Basically, the agitation has to be infrequent enough to allow by-products from the developer working in high-density areas to bleed over into less dense areas while the reverse, i.e., fluid with fewer development by-products moving diffusing to the denser areas, happens. The developer by-products (bromides principally) inhibit development. The mixed stripe at the interface between dense and less-dense areas thus constitutess a narrow band of altered development; not as inhibited as the dense area and more inhibited than the less-dense area. In essence, the very edge of the less-dense area has development inhibited, resulting in a very small stripe of reduced density. Conversely, the edge of the more-dense area (since it now has fewer development-inhibiting by-products) gets developed a bit more, resulting in a very thin stripe of greater density.

So, a clean edge between a very dense area and a, say, shadow tone less-dense area would look like:

Dense Area - Denser Stripe (caused by less-inhibited development) - Very Thin Stripe (caused by more inhibited development) - Slightly-denser Area (I wish I could do this graphically...)

Best,

Doremus

Tetenal Neofin Blue and Adox FX39 are designed to enhance the edge effects.
I'm not sure if Neofin is still available though.

Alan Johnson said:

The edge effect was much reduced when the iodide content of films was increased when they got their sharpness by other means than edge effect, though some edge effect remains.
I suggest new Tri-X or HP5+ as worth trying. The effect will be greater in an acutance developer than in a solvent developer.

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This is rather inaccurate.

Modern films are engineered to deliver very strong adjacency effects via the intentional placement of iodide (and other components), which when the emulsion is acted on by developer solvency (or anything else causing a degree of physical as opposed to chemical development), releases causing adjacency/ inhibition effects. Old (before mid 1950s) tech emulsions with iodide that was more buried would not produce the same results - and the problem is that everyone's popular understanding of developer and emulsion interaction is apparently permanently stuck in stasis in about 1948... This is part of the reason why people complain about some emulsions today not being able to be 'expanded' as much as old emulsions, as with time in contact with sulphite, more and more inhibition agent is released, which will effectively tamp down excessive highlight density. There are ways around this - use something much faster working & more aggressive (aka 'Universal' type developers). Some films (Delta 400) seem to have been engineered to be almost identical in different developers - likely through the composition of the developer control layers on the surfaces of the Delta emulsion crystal structures.

However, developing agents can also produce adjacency effects too. Low concentrations of Metol (less than 0.5g/l in working strength developer) will produce adjacency effects via exhaustion byproducts (e.g. Beutler and derivatives) - adding HQ or other source of semiquinone switches this off. The Metol exhaustion effect is likely why waterbath processes seemed to work with old emulsions that had relatively slower developer diffusion in/ out of the emulsion. Phenidone working on its own will produce extremely strong adjacency effects, but with suboptimal emulsion access - adding HQ (or similar - e.g. Ascorbate) resolves this but does not switch off the adjacency effect - instead it seems to make the effects controllable via relative proportions of the developing agents.

pH is another area which has an impact on sharpness - it roughly seems to follow a bell curve distribution, peaking at about 10 (carbonate buffering), but with borate buffering offering finer granularity - the irony is that borate buffering and things like Rodinal that use Hydroxide end up almost dead opposite each other in terms of sharpness in the pH to sharpness distribution - which is why Rodinal isn't any sharper than D-76, just grainier.

Lachlan,

I'm interested in your take on how the variables of developer activity, sulfite content of the developer, and agitation affect the formation of edge effects in relation to general and proportional inhibition of development in denser areas.

I would think that the formation of Mackie lines depended, at least somewhat, on the time allowed for inhibiting by-products to diffuse a ways through the emulsion into neighboring areas of different density. Something like continuous agitation, e.g., rotary processing, would slow down or stop such diffusion by replenishing those areas with fresh developer and thus significantly slow or stop altogether the formation of edge effects. Reduced agitation would have the opposite effect (as seems true in my experience).

Also, it would seem to me that developers that contain small enough amounts of sulfite so as to be non-solvent developers would inhibit general inhibition of development in dense areas simply because a smaller amount of developer-inhibiting compounds are being produced and, with frequent agitation, also the formation of edge effects.

With infrequent agitation, however, non-solvent developer, then might deliver more pronounced edge effects, since dense areas are less inhibited and develop more fully while the inhibiting by-products that are produced have the most influence on the lines of interface between denser and less-dense areas.

TIA

Doremus

I've seen Acuspecial (FX21) mentioned some where, but does anyone know the formula for the concentrate?

There's an article with an error here, later posts corrected an omission:

I played around with the original FX-1 formula with triX about 10 years ago. You can see the edge effects, less obvious in the NYC image., but obvious in the iron fence image.

john_s said:

There's an article with an error here, later posts corrected an omission:

Acuspecial FX-21 formula (Better than Rodinal!)

FX-21 developer formula for 1+14 dilution. All weights in grammes per litre. I do not yet have any development times. Component Amount in grammes Rounded Amount Metol 2.1495 2.15 Sodium Sulfite 30.0 30.0 Hydroquinone 1.0995 1.1 Phenidone 0.1245 0.125 Sodium Metabisulfite 6.15 6.2 Potassium Carbon...

www.l-camera-forum.com

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Hi John,

Is that the working solution? I was looking for the concentrated formula.

Thanks for the link.

Doremus Scudder said:

Something like continuous agitation, e.g., rotary processing, would slow down or stop such diffusion by replenishing those areas with fresh developer and thus significantly slow or stop altogether the formation of edge effects. Reduced agitation would have the opposite effect (as seems true in my experience).

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If agitation is above the level required to produce truly uniform development, then the effective edge sharpness differences between intermittent and continuous agitation are essentially nil. This has been investigated very, very thoroughly across the industry using microdensitometry - and Richard Henry also came to the same conclusions from his microdensitometric testing. Anyone without real microdensitometric data who is claiming differently is probably reporting other phenomena (lower overall density, printing on harder grades, etc, etc) that by other means are effectively increasing apparent edge sharpness, but it is not a direct result of the developer formulation. I think people need to understand in the clearest possible terms that most of what are claimed as 'innovative' developers and agitation techniques by various garden shed tinkerers can in fact be found being comprehensively outflanked in industry publications, patents & theses, where upon subjection to meaningfully rigorous testing and double blind print comparisons, they were found wanting vis-a-vis D-76 or similar. Huge amounts of time and effort were expended by extremely able chemists and engineers across the industry for decades to try and best D-76 in front of double-blind print panels. Well controlled development in D-76 with continuous agitation is quite capable of producing results that would easily fool the supplicants of various staining developers (i.e falsifiability) - the results of many claims about staining developers seem, in my experience of the people who work with them - and the results attained, from those developers often effectively running out of steam in ways that effectively compensate for a lack of understanding or enforcement/ reinforcement of basic process control - which more flexible and effective mainstream developers show up with rather unyielding and brutal clarity, especially on materials where the manufacturers took the risk of taking the training wheels off from the 1980s onwards.

Doremus Scudder said:

Also, it would seem to me that developers that contain small enough amounts of sulfite so as to be non-solvent developers would inhibit general inhibition of development in dense areas simply because a smaller amount of developer-inhibiting compounds are being produced and, with frequent agitation, also the formation of edge effects.

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Solvency is important to release inhibiting agents from the emulsion, but as I outlined, some developing agents can also produce inhibition effects under specific circumstances as well. So yes, you can produce inhibition effects from non-solvent developers, but again because of the way the mechanism seems to work, as long as agitation is over the threshold of even development, it has no meaningful impact on anything apart from density (which itself does have an impact on effective edge sharpness) which can be controlled for.

Only in very specific circumstances (e.g. halftones on litho) might there be a need for a period of intense agitation (while the chemistry diffuses into the emulsion) followed by absolute standstill - but that relates to the characteristics of litho development and halftone formation.

Doremus Scudder said:

With infrequent agitation, however, non-solvent developer, then might deliver more pronounced edge effects, since dense areas are less inhibited and develop more fully while the inhibiting by-products that are produced have the most influence on the lines of interface between denser and less-dense areas.

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In the kindest possible way, no. What seems to have excited manufacturing R&D about PQ was that it could produce useful inhibition effects in a way that was controllable (relatively at will) and largely insensitive to agitation (if over the threshold of evenness) while allowing replenished systems to be designed in ways that were seemingly not possible with developers that exploited Metol's exhaustion effects.

Keith Tapscott. said:

Hi John,

Is that the working solution? I was looking for the concentrated formula.

Thanks for the link.

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The concentration of the formula is half that of the original Paterson bottling. Dilute 1+14 for slow films, 1+9 for medium-speed and fast films, 1+5 for ultra-fast films. Try 9-12 minutes to start.

Component	Amount in grammes​
Metol	2.1495​
Sodium Sulfite	30.0​
Hydroquinone	1.0995​
Phenidone	0.1245​
Sodium Metabisulfite	6.15​
Potassium Carbonate (monohydrated)	22.035​
Sodium Bicarbonate	3.9​
Sodium Citrate	3.9​
Potassium Iodide	0.0825​
Potassium Bromide	0.33​
Sodium Hydroxide	5.0​

Augustus Caesar said:

The concentration of the formula is half that of the original Paterson bottling. Dilute 1+14 for slow films, 1+9 for medium-speed and fast films, 1+5 for ultra-fast films. Try 9-12 minutes to start.

Component	Amount in grammes​
Metol	2.1495​
Sodium Sulfite	30.0​
Hydroquinone	1.0995​
Phenidone	0.1245​
Sodium Metabisulfite	6.15​
Potassium Carbonate (monohydrated)	22.035​
Sodium Bicarbonate	3.9​
Sodium Citrate	3.9​
Potassium Iodide	0.0825​
Potassium Bromide	0.33​
Sodium Hydroxide	5.0​

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Thank you, I will make a note of that.
How did you obtain the formula if you don't mind me asking?

Keith Tapscott. said:

Thank you, I will make a note of that.
How did you obtain the formula if you don't mind me asking?

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If you read the thread linked to a few posts back, you can read some posts from Bill Troop about that.

john_s said:

If you read the thread linked to a few posts back, you can read some posts from Bill Troop about that.

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I only looked at the formula. I see now from the link it's in the FDC book which I don't have.
Thank you.

Lachlan Young said:

Well controlled development in D-76 with continuous agitation is quite capable of producing results that would easily fool the supplicants of various staining developers (i.e falsifiability) - the results of many claims about staining developers seem, in my experience of the people who work with them - and the results attained, from those developers often effectively running out of steam in ways that effectively compensate for a lack of understanding or enforcement/ reinforcement of basic process control - which more flexible and effective mainstream developers show up with rather unyielding and brutal clarity, especially on materials where the manufacturers took the risk of taking the training wheels off from the 1980s onwards.

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Lachlan,

Thanks for taking time for the lengthy explanation. Much appreciated!

I would, however, appreciated it if you could unpack the above sentence for me. I can't seem to make heads or tails of it.

TIA

Doremus

So, @Lachlan Young and @Doremus Scudder , you wouldnt happen to have any suggestions on 8x10" film that would be capable of similar characterstics as Tmax400 (for a lesser price)?