Acutance - is there something real behind the hype?

[Usagi]

Acutance, micro-contrast, border effect, Mackie lines, Eberhard effect... There's lot of terms describing pretty much same thing: The sharp contrast change on small area, usually giving fringe effect to the contrast edge thus working like USM in digital environment.

Okay, it's there.

Then comes the real world.

I have personally used various developers that favors acutance or are even designed to enhange it (heavily dilited Rodinal, DiXactol, Pyrocat-HD, ..)

But to be honest, I have never seen the effect on my prints. Ofcourse, I haven't done any side by side comparison with a negative having same subject and film, but another frame developed in d76/xtol and another developed in non solvent or acutance developer.

There might be other causes also, like poor focusing (is my grain focuser really properly adjusted?).

I used diluted rodinal (1+100 - 1+200) for a years with APX-25 without knowing actually it's capability to give acutance, especially with faster films. Then I came across with Thornton's book Edge of Darkness. It blew my mind.

That was the first time I really came familiar with acutance and the photographs on the book were so sharp!

This leads to title I gave to this thread: Has anyone seen Thornton's prints. Are they really that sharp as repros in the book?

Or more interesting question: Do you have own prints that really shines in the terms of perceived sharpness? :confused:

Something that's on the bar with the pictures of the Edge of darkness or unsharp masked scans/digital photos that we can see in photography magazines (often way too much sharpened with huge halos).

 

[David A. Goldfarb]

You can get some good advice from internet forums, but your own tests will tell you a lot more in cases like this.

Sodium sulfite produces a solvent effect only in sufficient concentrations, so you could try a test using a solvent developer like D-76 at two different dilutions. At stock strength and 1+1, D-76 produces a noticeable solvent effect, but at 1+3 it becomes more like an acutance developer.

If you're shooting 35mm, just shoot a whole roll of the same scene and cut off clips to try different dilutions and development times in different dilutions (like D-76 stock and 1+3), so that you can get two clips developed at two significantly different dilutions, but with the same overall contrast, so you can compare acutance effects.

Then make some prints, maybe a 5x7", 8x10", and then enlarge some segments with interesting detail to progressively larger enlargement factors, and see where it makes a difference. Look at them at arm's length, hanging on the wall, and close up.

 

[Usagi]

So I guess that I just have to do some 6x6 or 35mm tests and check can I get the perceived sharpness that I have seen on the books.

What if I am not able to get that good sharpness? Is it evidence of that something is wrong with my side or that images on the books have been tweaked?

 

[Ian Grant]

Non of the developers you've mention is particularly high Acutance. I don't think any are made or sold anymore.

The High Acutance developers like Acutol-S, Definol, Hyfin, Kodak HDD are the ones I came across. One problem is that you trade acutance against grain & tonality. This was why barry Thornton came up witl DiXactol and Sandy King Pyrocat HD these are developers that give a good overall balance with increased acutance but it's nothing like as maked as the high acutance developers.

I've seen some Thornton prints, they were not any better than many other fine high quality work from other photographers using different film/developer combinations. Barry had an obsession with quality which comes across in his books, but he wasn't really bringing anything new to the subject.

You have to do comparative test to see the differences in Acutance, Tonality etc and my own experience is that Rodinal & Pyrocat do bring out the best with certain films, APX100 & APX25, Tmx 100 & 400, and also Delta 100 & 400, and yes there is excellent acutance as well as fine grain and great tonality, and the micro-contrast in fine detail is definitely there in the prints.

But as many fine art photographers will tell you it's overall craft at the taking & processing stage rather than just choice of developer that brings about the highest possible quality.

Ian

 

[Ian Grant]

Just comparing "Edge of Darkness" to original Fay Godwin, John Blakemore, & Peter Cattrell prints, 3 of the UK's finest B&W workers, I'd have to say that the printing process in the book does give many of the images a slight edge in terms of apparent sharpness

Remember there's a very slight difference between RC papers & unglazed Fibre based prints. I know all 3 photographers I mentioned used Record Rapid of MCC for their images.

Ian

 

[nworth]

The main reason Thornton's pictures looked so sharp was that he always used a tripod. He discusses and demonstrates that at length in one of his books. A second reason was the MF format he used. There is really no substitute for square inches. Acutance developers can help, particularly with smaller formats. With larger formats, the effect is less obvious.

 

[dpurdy]

According to my researching it, acutance developers were developed to make the older thick emulsions thinner. The thickness of the old emulsions actually caused a bit of softness as the light rays spread out a bit as they penetrated it. Acutance developers were designed to develop only a thin layer of the emulsion and so reduce the light spread. A result of that is that grain is pronounced and edge affects occur.

The newer emulsions and especially the modern Tgrain type films are thinner and so the affect of the acutance developers is less and harder to see. The hard edged edge affect is much less than it was in the older films as well.

I personally use acutance developer for my film and I think it does give a bit more sense of sharpness. I generally shoot ACROS or Tmax 100. I did set up sort of a secret blind test one time by processing a friend's roll of film in my Beutlers acutance developer without telling him. He actually called me to say that the film I processed for him was the sharpest stuff he ever had. anecdotal I know

The other good thing about acutance developer is that it is cheap and gives nice tonality with compensating qualities.
Dennis

 

[Nicholas Lindan]

What if I am not able to get that good sharpness?

The bigger the film the sharper the image. Shoot an 8x10 camera and contact print the negatives and you will have all the sharpness you can hope for.

'Acutance' is an overblown term, not as overblown as 'tonality' but close. In any case 'acutance' is something I do my best to avoid - I don't want the perception of sharpness - I want real resolution.

The best that can be done with contemporary film for resolution is TMax 100 in Microdol-X 1:3, Xtol 1:1 is a very close second. The best ever is Tech Pan in Technidol, still available on ebay.

The term 'Micro Contrast' is much bandied about with little understanding. I define it as a film's ability to resolve low contrast detail. To get some measure of the effect in 35mm I tack a ~1cm/0.4" patch size 20-step Kodak Gray Scale along with a resolution target to a fence and take a picture of it from 10 meters/40 feet using the best equipment I can muster, on a tripod, mirror locked up and all that. I enlarge the negative 15x and examine the print with a loupe. Technical pan resolves clearly defined patches while TMax-100 shows a streak with no patches. Interestingly, on the black/white resolution target, the results of the two films are identical. Although I find very little research done on the topic I think it is an important one - and is the basis for the 'large format look'.

 

[dpurdy]

Also I went to an exhibit of Michael Kenna's yesterday. His Retrospective exhibit for his retrospective book. I am pretty dumbfounded at the sharpness he can get. Small prints that show some grain and way sharper than I can get with my cameras. Maybe he just finds the very best lenses for his hasselblad.
Dennis

 

[Nicholas Lindan]

Maybe he just finds the very best lenses for his hasselblad.

Tripod, tripod, tripod. And a really good well-damped tripod. Some camera/tripod combinations don't work well - put the camera on the 'pod, tap the camera hard with one hand gently resting on the 'pod and see if the rig vibrates - if it does then pick another tripod. Mirror lock-up will mitigate some camera/tripod resonance.

Also check the ground-glass alignment - focus on the moon and make sure it comes up at the infinity mark on the lens.

 

[Philippe Grunchec]

Don't forget the importance of the printing paper: some are sharper than others!

 

[RalphLambrecht]

But as many fine art photographers will tell you it's overall craft at the taking & processing stage rather than just choice of developer that brings about the highest possible quality.

Ian

very true

 

[RalphLambrecht]

Don't forget the importance of the printing paper: some are sharper than others!

Really? Which ones and what is the difference and why?

 

[RalphLambrecht]

Tripod, tripod, tripod. And a really good well-damped tripod. Some camera/tripod combinations don't work well - put the camera on the 'pod, tap the camera hard with one hand gently resting on the 'pod and see if the rig vibrates - if it does then pick another tripod. Mirror lock-up will mitigate some camera/tripod resonance.

Also check the ground-glass alignment - focus on the moon and make sure it comes up at the infinity mark on the lens.

Also, excellent advice. I never bought a camera where the focus did not require fine-tuning, and photographing without tripod is futile.

I also agree with the statement about acutance and resolution, and that a larger format is the better way to sharpness and not chemical miracle potions for 35mm film. However, I missed a statement about standing development so far. If you are using constant or even tilting development, you will not get the full benefit of an acutance developer.

 

[Philippe Grunchec]

Ralph, for example the late Forte Polywarmtone was extremely sharp, the Agfa MCC not. Graded papers are also supposed to be sharper than VC papers: don't ask me why!

 

[Ian Grant]

If you are using constant or even tilting development, you will not get the full benefit of an acutance developer.

Probably not with rotary processing, but L.F.A. Mason recommends continuous agitation for the first 10 seconds, then 5 seconds every minute/8 twists of the spiral with High Acutance developers. That's about normal for any developer for me.

Mason was head of Research at Ilford and would have been involved with Hyfin, which was the compnies High acutance developer

Ian.

 

[Ian Grant]

Ralph, for example the late Forte Polywarmtone was extremely sharp, the Agfa MCC not. Graded papers are also supposed to be sharper than VC papers: don't ask me why!

Philippe, I've got Polywarmtone & MCC prints here in Turkey, there's no difference in sharpnes. However the surface of MCC is slightly flatter it may make it appear less sharp but if you steam the print over a boiling kettle/pan the surface improves dramatically and they look more similar.

Graded papers don't look any different to VC prints, some people wrongly assume the high & low contrast emulsions are two different layers but they bare mixed prior to coating.

Ian

 

[Kirk Keyes]

Every paper has way more resolution than any negative that is enlarged onto it. You cannot see any differences in "sharpness" in any papers. (Asuming they are all of similar surface, i.e. no paper texture is involved.)

 

[keithwms]

Or more interesting question: Do you have own prints that really shines in the terms of perceived sharpness? :confused:

Something that's on the bar with the pictures of the Edge of darkness or unsharp masked scans/digital photos that we can see in photography magazines (often way too much sharpened with huge halos).

Personally, the very sharpest prints I have made are on LF polaroid. These far exceed anything I have made via any other process. The sharpness is almost as impressive as louping a slide.

Anyway perhaps you could show us a print that you aren't happy with and get some suggestions.

 

[Usagi]

Yes, the part of the 'acutance myth' might be the lens, perhaps combination of lens and fast film (iso 400).
Perhaps I haven't really seen the effect because lack of comparative tests and because I don't have Rollei SL66. So I have usually stop down a lot.

And yes, I use tripod and mirror lock up always. Lenses has own shutters, so there's no vibration.

But I don't own Hassy either...

 

[Keith Tapscott.]

Also, excellent advice. I never bought a camera where the focus did not require fine-tuning, and photographing without tripod is futile.

I also agree with the statement about acutance and resolution, and that a larger format is the better way to sharpness and not chemical miracle potions for 35mm film. However, I missed a statement about standing development so far. If you are using constant or even tilting development, you will not get the full benefit of an acutance developer.

John Sexton uses a Jobo rotary processor for his 4x5 film sheets developed in Jobo Expert-Drums and his prints look sharp to me.

 

[sanking]

I have never seen Barry Thornton's prints so am not able to directly address the question of the OP. However, I have seen the work of quite a number of other photographers, including those working with LF, and my impression is that the reproductions in books almost always have more apparent sharpness than real prints. I assume this is due to the use of sharpening techniques in manipulating the digital files, and/or to the slightly higher contrast that seems to characterize prints in books.

Sandy King

 

[keithwms]

There are plenty of reasons why a supersharp neg shot with a supersharp lens on supersharp film and developed with an acutance developer might still come across as unsharp in the print.

The way we perceive sharpness in the print has a lot to do with tone transitions i.e. lower frequency effects, and less to do with high-frequency sharpness and lp/mm and MTF etc. which is normally chatted about when people discuss sharpness.

If you are getting results that don't have enough perceived acuity for your taste, why not try a different film and paper, aim for a contrastier print, and try bleaching and toning etc.

By the way, I find that, quite generally, traditional-grain films give more perceived sharpness in print than the t-grain films. Honestly, I find it very hard to get a snappy, sharp-looking print from tmax or delta unless I shoot and develop for higher contrast in the neg. This isn't really a flaw of the film or a technical lack of sharpness in the film, it's just that the tonal transitions are just too gentle and gradual (i.e. dreamy) for my taste. Films like fp4+, hp5+, tri-x etc., developed in a standard way with good old D76/ID11 or such, have a lot more edge bite. They never disappoint me in terms of perceived sharpness of the final product.

Of course, if you want a film image to look like an oversharpened digital image, with too-fast transitions, well... run it through the digital workflow

 

[Keith Tapscott.]

]Films like fp4+, hp5+, tri-x etc., developed in a standard way with good old D76/ID11 or such, have a lot more edge bite. They never disappoint me in terms of perceived sharpness of the final product.

Yup, works for me.

 

[sanking]

Of course, if you want a film image to look like an oversharpened digital image, with too-fast transitions, well... run it through the digital workflow

Yeah, with no clue as how to proceed with a digital workflow from a film scan one will always screw up.

Hybrid.com or the LF forum is a better place to discuss the merits of digital workflow from film scans.

Sandy King