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Sorry Pico but I lost you here: "My other point concerns how grain can enhance accutance. Citation available". 

Care to explain to a non-native English speaker what this means? I did try to google it and found no definitions for "accutance", and I'm sure you have a good point

Thanks

Preben

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Acutance (one 'c') = "apparent or perceived sharpness." And there are a couple of mechanisms whereby increased grain equates to increased acutance, or apparent sharpness.

One is psychological and perceptual. We "think" something looks sharper, even if the actual image is fuzzy, if the grain itself is sharp-edged and clear. It gives us something to focus our eyes on.

This was observed in the completely pre-digital era - if one made a darkroom print with a superb enlarger lens, so that the grain of the negative was printed tack-sharp, even a picture made with a less-than-perfect camera lens (which included some Leica lenses, by today's standards) would be classified as a "sharp" picture, by most people. The crisp sandy grain was perceived as sharp detail and texture.

It is related to the Zeiss research in the 1960s that showed that people will think 40 lp/mm "looks" sharper than 80 lp/mm - so long as the image at 40 lp/mm has high edge contrast (what we now know as MTF).

In the digital era, this same perception is what allows "unsharp masking" or other digital sharpening to work. There is no way a computer can restore real detail to a picture (it wasn't at the scene) - but by enhancing the acutance or edge-sharpness of each individual detail, the picture "appears" sharper. Digital sharpening "adds acutance" by localized contrast increase (fewer "blurry" grays) between bright pixels and neighboring darker pixels, just as Zeiss discovered. As a side-effect, sharpening also often makes grain specks more obvious - just depends on one's USM settings.

The image below roughly simulates how digital sharpening (left) and more-intense grain (right) increase the apparent or perceived sharpness of a film scan, compared to the unmodified center version. Compared viewed from 1m, as well close to your computer screen.

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The other mechanism is more limited and technical.

A general-purpose film developer formula (D-76, ID-11, etc.) usually contains a solvent that dissolves metallic silver. It literally eats away at the edges of silver grains slightly even as they are developing, making them smaller. But also reducing the acutance, since the solvent is eating away at the edges of real detail, as well as "grain" detail. In those GP developers, the solvent proportion is a careful compromise, so as to reduce grain a bit, without nibbling away at the real detail too much. And the manufacturers' notes will say exactly that - "for a good compromise between fine grain and clear detail."

Some "fine-grain" developers (e.g. Microdol-X or Ilford Perceptol) carry an higher load of solvent, to really reduce grain size. Coincidentally, they eat away so much silver that they usually require exposing the film at a lower ISO, to "gain back" the total density of the negative via more light.

Conversely, some developers (e.g. Rodinal) contain relatively little solvent. No softening of edges (highest possible acutance), but also no reduction or smoothing of grain.

So it just a fact-of-life of photo chemistry that - for a given emulsion - larger grain and higher acutance track together.

BTW - the most common silver solvent in developers is sodium sulphite, because it also acts as a preservative for the organic developer compounds, and thus does two jobs for the price of one chemical. Some people who use Rodinal but don't like the large grain allowed by the native formula, add their own sodium sulfite to "take the edge off the grain" a bit. At a ratio of something like 5g sulfite powder per 500ml of diluted Rodinal (everyone has their own preferred "mix").

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On 2/22/2019 at 11:04 PM, TomB_tx said:

Like others above, I shot lots of Tri-X in the 1960s when doing more reportage work in available light - often at EI 1200 developed in Acufine. I also did indoor sports with 2475 recording film. Yet I never liked heavy grain - so when possible I used Panatomic-X (ASA 64).

In the 10 years since retiring and shooting film again, I've found I prefer the Ilford films, using PanF+ the most. I've had good tonality results with HP5+, but again prefer finer grain. Having tried TMax and Ilford Delta films, I prefer Delta, particularly for the handling when processing and drying. So I've ditched my remaining bulk of Tri-X and started loading Delta.

On the other hand, I do like the results of HP5+ in 120 size, where the grain isn't an issue. I guess I should 120 Tri-X again. Still have a soft spot for Kodak, and will be doing more Ektachrome for color. Looking forward to 120 size in that also.

Panatomic-X was also a favourite of mine (although I recollect it as being ASA 32), along with Techpan, and Tri-X.

These days, in 135, my preference is for Delta 100, with Tri-X for anything requiring a bit more latitude. I like, but don’t love, the TMax films. For slower stuff, I really like the Adox CMS 20 (reminds me of Techpan), and also sometimes use Rollei RPX 25 and Ilford PanF+.

For 120, Delta 100 and Tri-X are both crackingly good.

For LF, Delta 100 and Tri-X 320 are beltingly crackingly good.

I’m generally developing in R09 (Rodinal), or DDX.

Note: I’m even more enamoured by Ilford through both their dedication to film, and their customer service. I’m based in Malaysia, and sent them an e-mail about a few (3, if I recall) 120 Delta 100 films that I shot that had pieces of non-associated paper floating on them. They were very positive in their responses and, unsolicited, sent me replacement films plus a large assortment of 135 and 120 additional films. In addition to their excellent products, they deserve my custom.

Edited by EoinC
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5 hours ago, adan said:

Acutance (one 'c') = "apparent or perceived sharpness." And there are a couple of mechanisms whereby increased grain equates to increased acutance, or apparent sharpness.

One is psychological and perceptual. We "think" something looks sharper, even if the actual image is fuzzy, if the grain itself is sharp-edged and clear. It gives us something to focus our eyes on.

This was observed in the completely pre-digital era - if one made a darkroom print with a superb enlarger lens, so that the grain of the negative was printed tack-sharp, even a picture made with a less-than-perfect camera lens (which included some Leica lenses, by today's standards) would be classified as a "sharp" picture, by most people. The crisp sandy grain was perceived as sharp detail and texture.

It is related to the Zeiss research in the 1960s that showed that people will think 40 lp/mm "looks" sharper than 80 lp/mm - so long as the image at 40 lp/mm has high edge contrast (what we now know as MTF).

In the digital era, this same perception is what allows "unsharp masking" or other digital sharpening to work. There is no way a computer can restore real detail to a picture (it wasn't at the scene) - but by enhancing the acutance or edge-sharpness of each individual detail, the picture "appears" sharper. Digital sharpening "adds acutance" by localized contrast increase (fewer "blurry" grays) between bright pixels and neighboring darker pixels, just as Zeiss discovered. As a side-effect, sharpening also often makes grain specks more obvious - just depends on one's USM settings.

The image below roughly simulates how digital sharpening (left) and more-intense grain (right) increase the apparent or perceived sharpness of a film scan, compared to the unmodified center version. Compared viewed from 1m, as well close to your computer screen.

The other mechanism is more limited and technical.

A general-purpose film developer formula (D-76, ID-11, etc.) usually contains a solvent that dissolves metallic silver. It literally eats away at the edges of silver grains slightly even as they are developing, making them smaller. But also reducing the acutance, since the solvent is eating away at the edges of real detail, as well as "grain" detail. In those GP developers, the solvent proportion is a careful compromise, so as to reduce grain a bit, without nibbling away at the real detail too much. And the manufacturers' notes will say exactly that - "for a good compromise between fine grain and clear detail."

Some "fine-grain" developers (e.g. Microdol-X or Ilford Perceptol) carry an higher load of solvent, to really reduce grain size. Coincidentally, they eat away so much silver that they usually require exposing the film at a lower ISO, to "gain back" the total density of the negative via more light.

Conversely, some developers (e.g. Rodinal) contain relatively little solvent. No softening of edges (highest possible acutance), but also no reduction or smoothing of grain.

So it just a fact-of-life of photo chemistry that - for a given emulsion - larger grain and higher acutance track together.

BTW - the most common silver solvent in developers is sodium sulphite, because it also acts as a preservative for the organic developer compounds, and thus does two jobs for the price of one chemical. Some people who use Rodinal but don't like the large grain allowed by the native formula, add their own sodium sulfite to "take the edge off the grain" a bit. At a ratio of something like 5g sulfite powder per 500ml of diluted Rodinal (everyone has their own preferred "mix").

That is the best explanation and graphic demonstration I have seen - Thank you, Andy!

Edited by EoinC
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On 4/12/2019 at 8:14 PM, adan said:

Acutance (one 'c') = "apparent or perceived sharpness." And there are a couple of mechanisms whereby increased grain equates to increased acutance, or apparent sharpness.

One is psychological and perceptual. We "think" something looks sharper, even if the actual image is fuzzy, if the grain itself is sharp-edged and clear. It gives us something to focus our eyes on.

This was observed in the completely pre-digital era - if one made a darkroom print with a superb enlarger lens, so that the grain of the negative was printed tack-sharp, even a picture made with a less-than-perfect camera lens (which included some Leica lenses, by today's standards) would be classified as a "sharp" picture, by most people. The crisp sandy grain was perceived as sharp detail and texture.

It is related to the Zeiss research in the 1960s that showed that people will think 40 lp/mm "looks" sharper than 80 lp/mm - so long as the image at 40 lp/mm has high edge contrast (what we now know as MTF).

In the digital era, this same perception is what allows "unsharp masking" or other digital sharpening to work. There is no way a computer can restore real detail to a picture (it wasn't at the scene) - but by enhancing the acutance or edge-sharpness of each individual detail, the picture "appears" sharper. Digital sharpening "adds acutance" by localized contrast increase (fewer "blurry" grays) between bright pixels and neighboring darker pixels, just as Zeiss discovered. As a side-effect, sharpening also often makes grain specks more obvious - just depends on one's USM settings.

The image below roughly simulates how digital sharpening (left) and more-intense grain (right) increase the apparent or perceived sharpness of a film scan, compared to the unmodified center version. Compared viewed from 1m, as well close to your computer screen.

The other mechanism is more limited and technical.

A general-purpose film developer formula (D-76, ID-11, etc.) usually contains a solvent that dissolves metallic silver. It literally eats away at the edges of silver grains slightly even as they are developing, making them smaller. But also reducing the acutance, since the solvent is eating away at the edges of real detail, as well as "grain" detail. In those GP developers, the solvent proportion is a careful compromise, so as to reduce grain a bit, without nibbling away at the real detail too much. And the manufacturers' notes will say exactly that - "for a good compromise between fine grain and clear detail."

Some "fine-grain" developers (e.g. Microdol-X or Ilford Perceptol) carry an higher load of solvent, to really reduce grain size. Coincidentally, they eat away so much silver that they usually require exposing the film at a lower ISO, to "gain back" the total density of the negative via more light.

Conversely, some developers (e.g. Rodinal) contain relatively little solvent. No softening of edges (highest possible acutance), but also no reduction or smoothing of grain.

So it just a fact-of-life of photo chemistry that - for a given emulsion - larger grain and higher acutance track together.

BTW - the most common silver solvent in developers is sodium sulphite, because it also acts as a preservative for the organic developer compounds, and thus does two jobs for the price of one chemical. Some people who use Rodinal but don't like the large grain allowed by the native formula, add their own sodium sulfite to "take the edge off the grain" a bit. At a ratio of something like 5g sulfite powder per 500ml of diluted Rodinal (everyone has their own preferred "mix").

Excellent. There should be a FAQ with such useful information. 

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Well, I did few more experiments with TMax400 and Tri-X for myself. This time pushing the films in DD-X(1+4) (that's all I have). I ended up liking Tri-X pushed to 3200.

It seems if I do want landscapes then I am better off with fine grain like Tmax100 and if I want high speed casual/portrait kind of effect then pushed Tri-X is better for me.

See below. Therefore for the time being Tri-x is for me over Tmax400. As a fun experiment I tried to duplicate this look from M240 digital. I could create the contrasty look in LR but can't simulate the same grittiness in grain.

Leica IIIc/f, 50 Summitar, Tri-X pushed to 3200 (DD-X(1+4), 15:30 min at 22c)

Full pic and 1:1 zoom for the grain

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Edited by jmahto
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I also tried TriX again - snapshots of a friends 50th wedding anniversary with my 50 yr-old M4 and the film I used back then. I also developed in DD-X and was quite pleased with both the tonality and grain (reduced compared to Rodinal). Back 50 years ago I would have developed in either Ethol UFG (for 400 EI) or Acufine (for 1200 EI), but times change...

However, again I found TriX curled (or bowed) so much across the film that I could not get sharp scans on my V700, whereas the Ilford films lie much flatter. Then I shot a roll of Fomo 400 and found it lay flatter yet. I had to weight the TriX film flat for a week until it would scan sharply.

As a result I got some glass carriers for the scanner, which help a lot.

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  • 3 years later...
On 2/22/2019 at 2:19 PM, Einst_Stein said:

TRi-X is claimed the most popular B&W film for its tonality. It is more grainy than Tmax and Delta but people find it's pleasing.

Do you find Tmax 400 more preferable than Tri-X with your Leica?  

T-Max 400 is my preference over Tri-X or HP5+, if detail and fineness of grain are important. They usually are. Delta 400 is also good, but not quite as sharp or fine-grained as T-Max 400. I do recommend that beginners use Tri-X or HP5+ or FP4+, because they are easy to use. T-Max 400 is like a slow fine-grained film such as Pan-F+ (or Panatomic-X or KB14 both discontinued). I am therefore currently using Crawley FX-21 (home mixed, formerly available as Paterson Acuspecial) with T-Max 400. 

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  • 2 weeks later...

Back in the 1970s and 80s, my preferred films were Panatomic X (I remember it as ISO32), Pan F (50) and Tri-X Pan.  Sometimes FP4 or PlusX but mostly it was a choice between something very fine-grained for use in bright light, or something for lower light.  But Tri-X had another feature, which was its lovely grain structure.  The challenge was to get the grain to work with the texture of the image and it was especially good with skin tones.

An example below from 1980, most likely developed in undiluted ID11 that was replenished after each use, in a brown bottle that kept going for several years.

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Edited by John Robinson
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