Matte Black vs. Photo Black

[sanking]

As I see it, the longer the tonal scale, the more deliberate you must be to get a tonal change on the print. That reduces graining from the elimination of restrainer, and also from the inherent dot properties of the negative as well.

I don't know what the center point is of the x-Rite densitometer, but this could play a role in it some. Especially if you are printing colored negatives, as the colored inks are especially prone to what I call 'effective UV' density differences from the measured values. Epson blacks are not immune to that as well.



---Michael

Michael,

Would you comment on how graining is reduced with negatives of high DR "from the inherent dot properties of the negative."

I am not using colored negatives at this time. I use the Piezography inks with the Epson 2200, and composite black with the HP 9180. Neither are completely neutral in color, however, as both block more UV than Visual light.

Sandy

 

[Kerik]

Sandy - I'm using the Epson driver and (presumably) all of the inks and adding about 5% ink density. I haven't had time to go farther down the QTR path yet...

 

[sanking]

Sandy - I'm using the Epson driver and (presumably) all of the inks and adding about 5% ink density. I haven't had time to go farther down the QTR path yet...

Kerik,

Do you know the maximum UV blocking of your negatives made this way? I believe you have a UV densitometer now, right? Based on my own work in adding and subtracting black density with the 2200 and the HP 9180 I am guessing that a 5% increase in ink density would only add about log 0.10 to the UV blocking density of your negatives, which should put your maximum density at about log 2.3, or a maximum of log 2.4. That assumes of course that your base blocking density is similar to what I got with the 3800 in my tests.


Sandy

 

[Michael Mutmansky]

Sandy,

I'm talking about the fact that there is a minimum size dot that the printers can make. With dot gain, the size can be a little larger, and the UV density will be somewhat decreased and softened at the edges, but the resultant is that the printer is simulating a continuous tone with lots of individual dots. This is especially true in situations where the printer is not putting out a full ink load on the printer.

In those situations, when the printer puts out a dot of high UV blocking ink, it has the potential for that individual dot to be next to a void, or possible next to a low UV blocking ink. When that happens, visible graining can occur.

By using a long tonal scale process, the pt/pd will be less susceptible to this condition. For example, a dot that has UV density of 1.5d compared to a baseline density of .2d will print less white on a longer tonal scale process than a short tonal scale process, as the 1.3d difference is a smaller percentage of the total range on the longer tonal scale process.

It's for this reason (and a variety of others that I won't get into here) that I believe using a visible ink reflection based printer driver that relies on color ink combinations as the engine for making digital negatives is a fundamental shortcoming to produce the best digital negatives possible. Working within the constraints of that approach produces too many compromises. It may be possible to produce great negatives with a black-only ink approach that is available in the Canon and possible HP printers, but I haven't tried that.


---Michael

 

[Loris Medici]

Hi Ron,

I don't measure the negatives with a densitometer. That figure(s) come from 31-step tablet tests. The step tablets I use are real continuous-tone film tablets (those made by Stouffer for Mark I. Nelson)... AFAIK, there's no difference between optical and UV densities with those tablets -> especially when you're comparing the ES of different processes and/or coating solutions with different additives -> you just have to be sure that you're exposing enough to get maximum black capable with that particular sensitizer.

Regards,
Loris.

Loris-- I believe your measurement, but I expect the numbers you quote are for density in the Optical part of the spectrum, not UV densities (since I expect your 31 step wedge is calibrated for optical, not UV density.

 

[Ron-san]

Hi Ron,

I don't measure the negatives with a densitometer. That figure(s) come from 31-step tablet tests. The step tablets I use are real continuous-tone film tablets (those made by Stouffer for Mark I. Nelson)... AFAIK, there's no difference between optical and UV densities with those tablets -> especially when you're comparing the ES of different processes and/or coating solutions with different additives -> you just have to be sure that you're exposing enough to get maximum black capable with that particular sensitizer.

Regards,
Loris.

Loris--

Just for fun I got out my Xrite 361T densitometer and a Stouffer step wedge (21 step, part #T2115) and measured the density of a few steps in both the Ortho (visible light) range and in the UV range. Step 10 read Ortho=1.29 and UV=1.24. Step 21 read Ortho=2.92 and UV=2.84. I then tried the same readings from my Kodak 21 step wedge. It gave for Step 10, Ortho=1.38 and UV=1.33. For Step 21, Ortho=3.00 and UV=2.89.

It seems that the Stouffer and Kodak wedges have slightly different densities (not surprising since neither claims to be calibrated). But the UV and Ortho readings were very close for both wedges.

So, my supposition was wrong, and you are correct that these wedges have nearly identical densities for both visible light (ortho) and in the near UV.

By the by, I spent half an hour downloading and reading through every bit of literature I could find on the Xrite web site. And I could not find what wavelength the 361T measures when it measures "UV". Does anyone out there have that information? I would like to know if it is the same or different from the wavelengths measured by Sandy's densitometer.

Cheers, Ron-san

 

[Loris Medici]

Ron,

Probably the very slight difference between UV and visible light readings is because silver grains have different reflection/scattering properties for each type of light (and/or it's caused by some calibration/sensitivity issues with your densitometer). As you noted, it's negligible...

Regards,
Loris.

...my supposition was wrong, and you are correct that these wedges have nearly identical densities for both visible light (ortho) and in the near UV.

 

[sanking]

Ron,

Probably the very slight difference between UV and visible light readings is because silver grains have different reflection/scattering properties for each type of light (and/or it's caused by some calibration/sensitivity issues with your densitometer). As you noted, it's negligible...

Regards,
Loris.

I have also observed slight differences between visual and uv readings in both Kodak and Stouffer step wedges. I spoke to one of the technicians at Stouffers and was told that they do not routinely monitor UV density of their products.

Loris' suggestion that the difference is due to how silver grains scatter/reflect light sounds as reasonable to me as any other explanation I have heard. I don't believe it is a densitometer issue.


Sandy

 

[Michael Mutmansky]

That may be a possible explanation, but I suspect it has more to do with a very slightly non-neutral film color, due to the film base, and the interaction of the developer with the gelatin. In other words, I'll bet its a very, very subtle staining in the negative from developer exhaustion byproducts.

I tested my stepwedges in the past, and the ones I've tested are very close to the exact same value in both readings, within a few hundredths in the higher readings. I was surprised they were that close, actually.


---Michael

 

[sanking]

That may be a possible explanation, but I suspect it has more to do with a very slightly non-neutral film color, due to the film base, and the interaction of the developer with the gelatin. In other words, I'll bet its a very, very subtle staining in the negative from developer exhaustion byproducts.

I tested my stepwedges in the past, and the ones I've tested are very close to the exact same value in both readings, within a few hundredths in the higher readings. I was surprised they were that close, actually.


---Michael

That is very possible. Some non-staining developers do produce a UV blocking stain. Xtol is one example.

The interesting thing about the difference in Visual and UV readings I have seen, and that Ron's readings also indicate, is that the Visual or Ortho is actually a bit higher than the UV. This is the opposite of what one would expect..

Sandy King

 

[Michael Mutmansky]

Not if the color shift were in a spectrum that was closer to the central point in the visible spectrum than the UV Then, I would expect the vis to be higher than the UV.