Accutance comparisons

Mahler_one · Jun 12, 2007

On another thread a member and I started a discussion about accutance in stand developing versus accutance in developing using constant agitation. I don't want to reproduce the other interesting and informative post without permission, but I've copied my post here. In sum and substance, I'm wondering if there is objective evidence that accutance is improved with stand devloping versus developing carried out with continuous agitation.

Edwin

Interesting that you mention stand development. We are getting away from the subject asked on this thread, but I have often read about what you have just stated concerning accutance. However, I haven't seen much objective evidence that stand processing does indeed improve the accutance . If one does careful film testing using densitometers and step tablets then one can determine with a reallly good degree of certainty the developing time for a given subject brightness range such that one can obtain reasonably consistent negatives using the Jobo at a given temperature with a given developer at a specific dilution. No problems with shadow details, or highlights, unless I have done a poor job with my incident metering. Hence, again, I wonder if you might have some references that can point me in the right direction as to objective evidence that compares accutance with stand development versus development with constant agitation-same subject, same subject brightness range, same temperature, same developer at the exact same dilution. Prints made on the same enlarger, same paper, etc., etc. I certainly would like to learn how to make the best prints and negatives that I can, and perhaps stand development would yield better results in some situations. I'm going to move our discussion to another thread so that we can benefit from the experience of those who have also used both stand and agitation developing. Great that you brought the subject up. Thanks.

noseoil · Jun 12, 2007

Yes. tim

Mahler_one · Jun 12, 2007

Yes that there is objective evidence Tim? Have a reference?

Thanks.

fhovie · Jun 12, 2007

I don't know how to express it mathematically or with cool charts but with TRI-X 4x5 320 sheets in Pyrocat-P 1:1:100 with constant agitation, a sharp edge has very slight fade transition that looks ok when printed. Hand agitation will show a smaller fade transition and will look slightly sharper. At 1:1:150 for 30 minutes there is a definite line where the transition is that causes the print to look razor sharp and at 1:1:150 for 55 minutes the Mackie line is so big it is distracting.

With FP4+ - the same test will show similar results except the FP4+ will have the same sharpness of TRI-X at 30 minutes when developed at 55 minutes and amazingly, will still have such tight grain that a 30"x40" enlargement will show no grain in the sky or light mid tones at all. This is now my process for a SBR of 5 or so - The DR will be about 1.35. For SBR of 7 or higher, I still use FP4 but only stand process for 30 minutes. During my stand processing, I do 4 evenly spaced short gentle agitations. (Semi-Stand - I Guess)

Mahler_one · Jun 12, 2007

Thanks. Great information.

E

Tom Hoskinson · Jun 12, 2007

My experience is similar to fhovie's.

For repeatable sharpness/acutance tests, I contact print an Edmunds USAF chrome on glass resolution chart onto a test sheet of the film and include a 21 step Stouffer density scale.

Alan Johnson · Jun 13, 2007

I did a few tests. FWIW they only seem to support the received wisdom that stand development improves apparent sharpness with LF. IIRC this is mentioned in previous Pyrocat stand threads.
I photographed a light gray card on a dark gray card,stand developed Rodinal 1:200 90min 68F and made a 10x enlargement of the edge.Films fell into 3 groups:
(1) Showed a light line (border effect) about 1mm wide - Tri-X, Plus-X , HP5 ,Adox/Efke 25&100.
(2)Showed a narrower,harder to see light line on the 10x enlargement - Delta 100&400 ,FP4 , Pan F , Lucky SHD 100 new.
(3) Hard to see any effect at all - T-max 100 ,Acros.

I recon for an increase in apparent sharpness on the print a light line(edge effect) width of about 0.1-0.2 mm is wanted. This corresponds to using one of the group (1) films and making a 1x or 2x enlargement.I haven't actually done this. IDK if Pyrocat stand gives the same light line effect as Rodinal stand.

Mahler_one · Jun 13, 2007

Interesting Alan. One wonders if there is, indeed, ANY objective test that can measure edge sharpness and the effect(s) of stand development with various film/developer combinations. Since the edge effect is perceived, then one might argue that everyone will perceive the effect differently. Perhaps such perception is what "artistry" ans "style" is about. It is almost as though one is resurrecting the, "How many angels can dance on the end of a pin" argument. Perception is one man's reality, but one would certainly like to have an objective way of telling if there is a "real difference" in the effects attributed to the various methods used in the darkroom. Indeed, if one goes to Photographers Formulary, or reads Steve's wonderful book on film developing, the number of film devloping recipes is truly prodigious. Absent objectivity one is reduced to evaluating various "claims" with some excused skepticism. I am not, of course, denigrating the reports of such effects ( or making light of those who issue steadfast claims for the unique effects of various techniques ), but simply saying that such claims might be merely opinion. Please-no flames intended to anyone who has a favorite way of developing and printing.

Edwin

Neal · Jun 13, 2007

Dear Edwin,

There was a short article in the March/April 2006 edition of Photo Techniques explaining edge effects. The authors stated that edge effects are real and gave an explanation as to why. There were supposed to be follow up articles (in the "Photographic Myths" section) on the subject but the ensuing months did not deal with it directly.

Neal Wydra

David Brown · Jun 13, 2007

Neal said:
There was a short article in the March/April 2006 edition of Photo Techniques explaining edge effects.

Did the article have illustrations? I'd be very interested in "seeing" this effect vs. an explanation.

gainer · Jun 13, 2007

Whatever test is used, it should be an objective measurement such as a microdensitometer trace across the boundary in question. The human visual sense has its own edge effect which will appear at a truly sharp boundary between light and dark areas. In other words, a true step change in brightness may have the appearance of a non-minimum phase response. The bright side will appear brighter and the dark side darker. Personally, I think we should be looking for the most accurate portrayal of edges instead of the artificially enhanced edge.

noseoil · Jun 13, 2007

David, here's a link to a shot with pronounced edge effects. This is a crop from a 35mm shot in which my son (this picture) and his friend were standing side by side. Since it was Efke100 and minimal agitation, the edges are pretty exaggerated. In a larger format with less enlargement, they would not be as visible.
(there was a url link here which no longer exists)

Neal · Jun 13, 2007

Dear David,

The article did have illustrations, but the illustrations were generated digitally (as they noted in the text). Further, they were square patches rather than images to (I think) illustrate the concept rather than provide an example. I remember hoping that they would get around to the specific topic again but I don't believe they have.

Neal Wydra

fhovie · Jun 13, 2007

Thornton's "Edge of Darkness" is full of objective test data about sharpness accutance and resolution which are not all the same thing. Sharpness (increased accutance) IS A DISTORTION. It is an artificially produced line using chemistry that manipulates silver grains and or the penetration of developer into the emulsion surface by tanning. Using a resolution test, this will reduce the resolution but make the image appear sharper. The greatest resolution film I ever used was Tech Pan. It did not look that sharp. It takes grain to make an image look sharp. All this is well documented in Thornton's book.

One thing I know about the folks on APUG is that when several of them report that something works, that is to me as good an objective proof as I need. The end result is not going to be someone looking at a photo on a wall with a microscope but instead it will be the emotion generated by the subject matter and how well the image conveys that subject. That is why I don't really care about what the negative looks like under a microscope. I care about what the enlargement looks like (not withstanding the effect of negative stain on the print) - You can get an image that is too sharp as well. The finest minds in photography are here (and I am not counting myself) and I count most of my modest success at photography from taking their word for it.

noseoil · Jun 13, 2007

"One thing I know about the folks on APUG is that when several of them report that something works, that is to me as good an objective proof as I need." fhovie

Evidently, this type of question is looking for more than a simple answer. I guess it is sort of like the film testing question and "what development time should I use" if I don't want to actually do the test myself (for whatever reason, pick one). tim

Bruce Watson · Jun 13, 2007

Mahler_one said:
I wonder if you might have some references that can point me in the right direction as to objective evidence that compares accutance with stand development versus development with constant agitation-same subject...

I live near a university research library. Three or four years ago I mounted a fairly extensive research effort to try to understand what effects accutance, and in particular what effects the growth of Mackie lines.

What I found is that the effect isn't much explored in the literature. What there is isn't conclusive. For example, my reading of Richard J. Henry's book Conrols in Black-and-White Photography is that Henry finds only a weak connection between agitation method and the formation of Mackie lines. Grant Haist doesn't seem to make a determination either way in his two volume tome Modern Photographic Processing.

In searching the 'net I've found many many anecdotal accounts that link all kinds of things to agitation. But no scientific evidence.

My research let me to conclude that accutance is complex and poorly understood. There may be a component that can be controlled somewhat by agitation, but there are clearly other components that are not controlled by agitation.

Unless someone is willing to do the research and publish the results in a peer reviewed journal (and if they have and I've missed it I would love to know who and where so I can go read it myself), I don't think you'll find a conclusive answer to your question. Even then you'd need other independent researchers to verify the first publisher's results. And in today's corporate R&D environment, I'm not going to hold my breath waiting for this to happen.

Mahler_one · Jun 13, 2007

Thanks very much to all who responded with such interesting information.

As to accutance and how to measure such....I am reminded of a comment that a Supreme Court Justice made when he ( was before the first female Justice ) was asked to define what "obsene" meant....and to paraphrase the reply, the response was to the effect that, "I can't perfectly define it, but I know it when I see it"...

Edwin

Alan Johnson · Jun 13, 2007

I thought digital might give some indication of how wide an edge effect should be.I sometimes print scans 2000 pixels wide on 8 inch (203.2mm) wide paper,about 10 pixels/mm. These are sharpened with a radius of 1 pixel,which corresponds to a width of 0.1mm. 1 pixel radius has no fundamental basis but is quite often recommended for sharpening, presumeably because it looks about right. So 0.1mm for my preferred edge effect width.

gainer · Jun 13, 2007

Would not the 0.1 mm edge effect cause maximum resolution in a print to be 5 lines/mm or less? What happens to picket fences and the like when the edge effects meet in the middle?

Tom Stanworth · Jun 14, 2007

I dont want to drag this off topic...but how should one conduct stand processing for sheet film? I have done semi stand and stand on an experimental basis for 120 rolls in a regular Paterson tank and got no streaking or problems (apart from the fact that 6x7 HP5+ was TOO sharp and had the same look as an oversharpened digital file so clearly I needed more agitation). I would be very interested in trying this with 5x4 to 10x8 but in these formats I use an orbital processor. What techniques would you suggests for sheet film: Trays? I am just wondering if any precautions are required to prevent marks/artificats?

I totally agree with the impact the film has. HP5+ moderately enlarged is the 'crispest' film I have ever used. It has such a sharp grain structure and I noticed a huge difference when I had a play with acros and other fine grained films in that as expected, the results were more subtle. I was shocked when I printed the HP5+ and found it loooked like a digitial file . I am definitely going to experiment with this technique for my larger formats but found that with 120 semi stand was more extreme than I needed considering my enlargements were typically 11x14-12x16.

I have to say, I have never had FP4+ enlarged 8 times to 40" without visible grain, but then again that depends on distance. I can see the grain on Fp4+ on 24" print where theyere are sky or medium light tones with pyrocat HD, D76 etc. I guess we all have a different idea of what visible grain is. I find FP4+ is defintely showing a break in tonality at 20" if developed in D76 1+1 and subtle Z5-7s are present and my 10x8 colour head is as diffuse as they get!

Tom Hoskinson · Jun 14, 2007

Tom Stanworth said:
I dont want to drag this off topic...but how should one conduct stand processing for sheet film? I have done semi stand and stand on an experimental basis for 120 rolls in a regular Paterson tank and got no streaking or problems (apart from the fact that 6x7 HP5+ was TOO sharp and had the same look as an oversharpened digital file so clearly I needed more agitation). I would be very interested in trying this with 5x4 to 10x8 but in these formats I use an orbital processor. What techniques would you suggests for sheet film: Trays?

I totally agree with the impact the film has. HP5+ moderately enlarged is the 'crispest' film I have ever used. It has such a sharp grain structure and I noticed a huge difference when I had a play with acros and other fine grained films in that as expected, the results were more subtle. I was shocked when I printed the HP5+ and found it loooked like a digitial file . I am definitely going to experiment with this technique for my larger formats but found that with 120 semi stand was more extreme than I needed considering my enlargements were typically 11x14-12x16.

I have to say, I have never had FP4+ enlarged 8 times to 40" without visible grain, but then again that depends on distance. I can see the grain on Fp4+ on 24" print where theyere are sky or medium light tones with pyrocat HD, D76 etc. I guess we all have a different idea of what visible grain is. I find FP4+ is defintely showing a break in tonality at 20" if developed in D76 1+1 and subtle Z5-7s are present and my 10x8 colour head is as diffuse as they get!

Tom, BTZS type tanks work very well for me stand and semi-stand processing single sheets of film.

Slosher Trays (Summitek, etc) work very well for me stand and semi-stand processing up to 4 sheets of film at the same time.

Conventional trays are fine for stand and semi-stand processing single sheets of film.

Early Riser · Jun 14, 2007

Edge effects are a common side effect from stand development, that gives the illusion of greater acutance. Another side effect is mottle due to bromide build up and uneven development, either of which is ruinous to an image and nearly impossible to correct post development. When you do stand development you do face this possibility. Personally I would never risk images that I perceived to have value trying for that last little bit of accutance. You can always choose higher accutance films and developer combinations if you want. Also why is there such a desire for super acutance? Are you doing aerial reconnaissance?

There is no silver bullet film/developer combination that makes images magic. There is but a weighing of the various attributes of each film developer combination and the compromises and qualities that we each deem to our satisfaction.

Mark Antony · Jun 14, 2007

I have an old Book, with diagrams and an explanation of Mackie lines and the 'Eberhardt' effect. It seems to suggest that they are unwanted effects due to lack of agitation and or Solarisation.
I can't post the images but may do an article on my blog if there's enough interest.

noseoil · Jun 14, 2007

There are so many different factors when considering "sharpness" in a print, that the list can get very long. The effects of development are just one portion. Film type, developer, enlarger and light source are all important variables.

The type of enlarger can make a huge difference. This was illustrated to me by Donald Miller earlier this year when I had a chance to see his "point source" enlarger at work up in Phoenix. I had a decent sheet of film from a minimal agitation 4x5 & pyrocat development. His rendering of this image was vastly different than what I had done previously (with the diffusion enlarger I have). It was much sharper, cleaner and brighter. Just one example of a different part of image making. tim

MarkS · Jun 14, 2007

Anyone interested in these issues should read the relevant parts of the publication "Scientific Imaging with Kodak Films and Plates", Kodak publication # P-315. My 1987 edition covers this in some detail. The book is likely out of print but should be findable...
ISBN #0-87985-475-8
LoC card catalog #87-82421
EK cat no 145 9742

Accutance comparisons

Privacy & Transparency

Privacy & Transparency