Increasing accutance in negativesgreenspun.com : LUSENET : Large format photography : One Thread
Following suggestions I found in Anchell's book on the subject I attempted to increase accutance in my 4x5 Plus X negatives by decreasing the concentration of HC110 (dilution B) to 1/3 ounce developer vs 31 ounces of water and by extending development time to 18 minutes @ 68 degrees F (this was an approach recommended by Adams, according to Anchell). What I wound up with were negatives that were highly underdeveloped, even for 18 minutes in the juice. So I'm wondering how long I would have to cook these negs in order to get them where they ought to be.
Any experience out there with increasing accutance in this manner?
-- Robb Reed (firstname.lastname@example.org), June 20, 2000
Could be that you've diluted the developer to the point where there simply isn't enough of the active ingredients to develop the amount of film you're putting through it. i.e. The developer is getting exhausted before it's done the job. How many sheets did you try to dev with 1/3 ounce of developer? If you feel like risking some more film, try cutting the number of sheets down in the same quantity and dilution of juice. I'd guesstimate that 1/3 ounce will only do for 1 or maybe 2 sheets of 5 x 4.
-- Pete Andrews (email@example.com), June 20, 2000.
Robb-Pete's right with regard to the developer being exhausted before it can do its job. I looked up Adams "The Negative" (1981 ed.) pages 226-228 and he clearly states that with highly dilute developer you must use the same amount of developer(concentrate) per given surface area of film as you would for normal dilution and development, you must therefore use larger vessels to develop the film to accommodate the increase in volume. Regards, Trevor.
-- Trevor Crone (firstname.lastname@example.org), June 20, 2000.
Robb, I have found that by using PMK (Pyro) accutance is greatly increased, Also I have just started using DiXactol ( a 2 bath dev) which is producing spectacular results, fine grain, high accutance, and is more environmentally friendly than PMK.It also works well with ALL films!! Just a thought!! Regards Paul
-- paul owen (email@example.com), June 20, 2000.
Why is acutance so important? When acutance increase, grain and gradation suffer (says the Film Developing Cookbook). High acutance is created by having high contrast at a micro level. This high contrast leads to blown out highlights and choppy gradation. High acutance is not always good.
-- William Marderness (firstname.lastname@example.org), June 20, 2000.
Adam's was suggesting HC110 Stock Solution (not concentrate) at 1:31. I've used this for the time range you are talking about, and development was fine (not underdeveloped).
HC110 Dilution B is 1:31 from concentrate or 1:7 from stock.
I am sure your problem was not enough developer for the area of film. Kodak suggests 20 sheets of 8x10 for 1 gal of Dilution B. With B being 1:7 of stock, that's 16 oz of stock for 20 sheets, or 1.25 oz. of stock per 8x10 sheet or 4-4x5 sheets.
By the way, anytime you dilute HC-110 other than 1:31 concentrate or 1:7 stock, it's incorrect to call it Dilution B.
For William, regarding acutance: read in the Developing Cookbook why the movie industry never went to fine grain (silver solvent) developers. Further, acutance isn't primarily micro-contrast, but edge effects (as I see it, anyway). Acutance is key to the perception of a sharp image. A proper balance between acutance, grain, and tonality is all in the eyes of the photographer. Anyway, with 4x5 grain and tonality are rarely an issue, and acutance is something well worth striving for.
-- Charlie Strack (email@example.com), June 21, 2000.
High acutance (high contrast at the edges) is high micro contrast. I am not suggesting a super fine grain developer. I am saying that high acutance is not so important, and sometimes may be undesirable. Here is what is bad about high acutance (all from the Film Developing Cookbook): 1) High acutance leads to a rough, soot-and-chalk gradation. 2) High acutance makes sharp areas appear sharper, but it also makes blurry areas appear blurrier. If you use an older lens with mediocre sharpness, if your camera shakes, or if your subject moves in the wind, high acutance will emphasize the blurriness. 3) High acutance increases grain (not important for large format, but neither is maximum sharpness).
Try this formula for really high acutance:
Metol 1g Sodium sulfite 5g Sodium carbonate, mono 5g To make 1 liter
-- William Marderness (firstname.lastname@example.org), June 21, 2000.