Jill, I don't know that I follow your reasoning. I have a different idea of how to accomplish this, you tell me if it is possible to accomplish judging from your experience. O.K.?
1. Measure the density range of the camera (photographic) negative.
2. Taking a Stouffer 21 step tablet, shoot an exposure of the step tablet to determine an exposure that will expose the density range of the camera negative onto the lithographic film that you are using.
3. Make an unsharp mask of the photographic negative. (typical peak density of .35)
4. Taking the camera (photographic) negative, and register this with a sheet of unexposed litho film. Shoot an exposure through the camera negative to cover the density range of Zones I-III (example of densities .10-.35). Process the litho film. This will produce a positive (high density) of the low density areas of the camera negative.
5. Contact print this litho positive with an unexposed sheet of litho film to produce a negative of this positive. (This will become the mask, when place in register with the camera negative, through which one of the print exposures (shadow) is made.
6. Take the positive litho mask produced in step 3 and register this with the camera negative. (effectively blocks low density regions of the camera negative) and another sheet of unexposed litho film. Shoot an exposure to cover the densities of .10 through 1.00) Zones I through VI. Since we have blocked the low densities with the litho mask previously produced only the camera negative densities of .35 through 1.00 will be exposed. This will produce a positive of the camera negative.
7. Take the positive produced in step 5 and register it with an unexposed sheet of litho film, expose it to produce a negative of the positive. This will become the mask through which the midtones of the camera negative are exposed when producing the print.
8. Taking a Stouffer step tablet determine exposure on the paper used to cover the density range of the camera (photographic) negative.
9. Take the positive produced in step 4 and the positive produced in step 6 and register them with the camera negative. Dial in high contrast filtration and expose the highlights of the camera negative onto the printing paper. The high contrast will effectively separate the high values which are placed on the characteristic curve of the film's "shoulder".
10. Take the negative produced in step 7 and the positive produced in step 4 and register with camera negative and expose the enlarging paper with lower contrast filtration then the previous exposure. This produces the midtone print exposure. Since the midtone densities reside on the "straight line" portion of the film characteristic curve, they are typically already well separated.
11. Take the negative mask produced in step 5, register it with the camera (photographic) negative and expose the enlarging paper with high contrast filtration to create greater separation of the shadow ranges. Densities represented on the "toe" of the films characteristic curve.
12. Make an exposure with the unsharp mask( step 3) in register with the camera (photographic) negative. To blend the various demarcations that may exist in the previous exposures and increase the prints apparent sharpness through edge effects.
I might add. That the print exposures previously addressed would need to be adjusted by the peak density value of the unsharp mask (typically .35). Since this exposure will be added in the last (step 12) exposure.
The effects of this means of printing are to defeat the characteristic curve of the camera negative and to also create much more tonal separation throughout the print. (Open shadows and well separated tonality in the highlights).
This is where I am in the process. As a person working in graphics materials, does this seem plausible?
I can say I think so, but you are using terms I am not quite sure. Let me try to replay in my pitiful wording and tell me if I understand.
Essentially, it appears that you are originally analyzing to find exposure goals.
1. Then you are doing my step 3 first, right? Over-expose (from what a 50/50 break would be), to expose all but the shadows. And the shadow is open.
2. Take a neg of #1, use this to block the shadow region for step three.
3. Repeat #1 with #2 registered over original neg and not such a high exposure such that the mid-range is printed.
4. Take a neg of #3. Midtones are open.
5. Use 1 & 3 registered over original negative to block shadow and midtone, take a neg, printing only highlights.
6. Take a neg of that, open highlights.
IF, this is what you are saying then I think we are doing the same basic thing from a different perspective, and yes I think yours would work fine and maybe even better.
My particular reasoning was simply based on #1 how to isolate the tone ranges (particularly the midtone) and #2 making sure they would be clear in the desired region rather than black.
In case you want to educate me. The wording I am intuiting, I think< but am not sure of are
peak density-is this the highest , lowest, or an aim density.
Stouffer 21 step tablet- is the a color/grayscale type of tablet?
Zones - again I am imagining that this refers to highlight vs midtone vs shadow but stepped with more than the three steps I appear to speak about.
It seems to me that where we are failing to communicate is that the first generation mask of a camera (photographic) negative will be a positive. On a camera (photographic) negative, the shadows are the lowest density. Therefore, when placing the camera negative in register and contact printing with unexposed lithographic film, the shadow (low density negative regions) will be the first to expose the lithographic film. This exposure of the lithographic film would be represented by density on that film.
Ultimately the aim is to have three litho film masks which are clear (no density) in the areas of the desired densities (shadow, midtone, and highlight) which exist on the camera (photographic) negative to expose the enlarging paper. All other densities apart from these must be blocked by high densities on the lithographic film masks.
The Stouffer 21 step tablet is a calibrated tablet of 21 densities separated by values of .15 or 1/2 stop. Each stop is a log value of .30 or a doubling or halving of the amount of light which is exposing the film or paper. Thus this tablet will cover 10 1/2 stops of exposure.
Peak density is the highest density which would exist on an unsharp mask. An unsharp mask is a low density unsharp positive of a camera (photographic) negative. It is a continual tone mask. It is for this reason that I use dilute (1-30) Dektol to develop the half tone ortho-litho film. The highly dilute Dektol will cause the high contrast litho film to act as a continuous tone material.
Zones are the terminology which Zone System photographers refer to as stops of reflected light defined within a scene or object. The lowest would be Zone I which has a density of .10 above film base plus fog (unexposed but developed film)--it would be defined in a print as the deepest black possible and would not represent any texture. Zone II would be the next stop (doubling) of light exposing the film. This progression continues to Zone X which is typically represented as paper base white with no texture represented. The highest Zone which we normally concern ourselves with is Zone VIII which is the highest value showing texture within a print. This Zone (VIII) is typically targeted to a camera negative density of 1.25, when printing with a diffusion light source enlarger.
The characteristic curve of a film or of a paper is a depiction of the densities, placements of densities, and degree of slope of the contrast within that materials design. It would best be described as an elongated and gradual "S" shape. The lower and upper terminus of this shape are what are commonly termed the "toe" and the "shoulder" of this curve. It is in these regions that the slope is diminished from that represented on the "straight line" section that joins these two regions. Because the degree of slope in the upper and lower terminus are reduced the contrast, and by consequence, the tonal separation is not well differentiated.
I hope that I have cleared some of the miscommunication that seems to be occurring and that I have answered your questions.
OH< OH< You're absolutely right! I think I figured out where we are differing. . . you are starting with the original negative and I am starting with a print. DUH! Dummy me, up till recently, no one ever brought in their own negatives. Everything that needed this kind of quality control has come in as prints or artwork, so I was starting with the positive image. I should be exactly backwards. I will ponder this and evaluate if it is so and reply later. Of course I will still be testing it ASAP, which now looks like sometime next week, I'm swamped. http://apug.org/forum/html/emoticons/biggrin.gif I am really looking forward to trying this because, wow! couldn't it do wonders in a difficult situation.
Lunch is over and my day is gonna be long. Bye.