Piezography for digital negatives?

[clay]

The method that Ron outlines in his book using QTR is amazingly powerful. It allows complete control over the ink distribution by the driver, which is something no other method I have seen allows you to do. I spent some time getting my 7800 completely linearized in the driver itself, and the negatives I am getting now are way ahead of anything I have tried to date, on any printer or with any other method. They look and print like in-camera negatives.

The joker in the deck is the behavior of driver or the RIP. Until you can predict accurately what it will do, with each ink, at each density, things like graining and weird UV density behavior that does not correspond to visual density behavior are inevitable.

The driver programmers design their programs to behave for visually based results, and not necessarily UV based results. With some printers, there is enough correspondence between the two that it is easy enough to just use a curve to make nice negatives. Some others (like my 7800) make life a lot more difficult until you understand the ink behavior.

I highly encourage people to buy Ron's book and dive into the chapter on QTR if you are using the Epson printers.

 

[sanking]

Clay at al,

I must admit to not having yet read Ron's chapter on controlling ink distribution with QTR. On my agenda, but not there yet.

Hopefully Ron provides some way to navigate through QTR. The documentation provided with the product leaves something to be desired IMO. I really don't think this method is going to catch on with most users unless something is done to provide a clear path for navigation.

Over the past several days I have printed on Pictorico several large 101 step wedges that also contain gradients and 1-pixel, 2-pixel and 3-pixel grids. These were made on the 2200 with the Epson inks in one of the original PDN emerald type colors, and also on the 2200 with Piezography. I also made the same target with the HP B9180 using composite black and a Red array color.

Visual inspection of the four step wedges show tht the Piezograhy inks definitely print with higher resolution on Pictorico because with this combination the 1-pixel pattern was clearly visible. On all of the other targets the first clearly visible patterns was the 2-pixel grid. Score one for QTR and Piezograhy.

Printing of the targets on COT 320 with VDB pretty much equalized everything. In terms of resolution, the 1-pixel grid, which is clearly separated on the Piezograhy target, can not be read on the print. In terms of smoothness, all of the negatives print about the same, as the surface texture of the paper breaks up any grain. In terms of printing the gradient, all of the negatives printed about the same.

My impression is that any of the targets would print same as an in-camera negative on pt./pd., not because there is no difference between them, but because the paper support in this case is the limiting factor in both sharpness and smoothness. I am thinking of testing on a plate vellum surface, which may give slighter better resolution than COT 320.

Sandy

 

[Ron-san]

Clay at al,

I must admit to not having yet read Ron's chapter on controlling ink distribution with QTR. On my agenda, but not there yet.


Sandy

Sandy and Clay---

I agree with Clay, using some RIP that gives you total control over the inks, like QTR, is really the ultimate way to go. I also agree with Sandy, that the current documentation, including the chapter in my book, leaves something to be desired.

My latest effort to fix this situtation is to re-write a 30-some page manual that attempts to tell everything I know about using QTR for making digital negatives. Whether this will turn out to be user-friendly enough for most people, I will have to leave to you guys to decide. I am currently having my web guy upload it to my website where it will be a free pdf down load. Hopefully within a week or so. When it is up, I will welcome any and all feedback on its usefulness. My website is www.ronreeder.com I hope the QTR manual will be on there soon.

Cheers, Ron

 

[mkochsch]

Pixel Grids

Can you post these 1, 2, 3 pixel grid patterns so I can better understand what they look like. Is this like lpmm rating the material?

~m

 

[sanking]

Can you post these 1, 2, 3 pixel grid patterns so I can better understand what they look like. Is this like lpmm rating the material?

~m

It is just a grid of alternating black and white pixels. The number per inch determines the limit of resolution. If you set it up so tht there are 360 ppi and you can read this pattern on the negative material and/or on the print, resolution is about 7 lppm. (360/25.4/2). If you set up the grid so that there are 720 ppi, and can read the pattern on the negative and/or on the print, resolution is on the order of 14 lppm.

Anything you can read over about 8-l0 lppm on the negative will be lost in translation in pt./pd. because no paper commonly used in this process can resolve more than this. Carbon and silver are capable of higher resolution on smooth surface papers and could potentially benfit from higher resolution.

Sandy King

 

[sanking]

Just one further note, which may speak to the importance Clay mentioned of adjusting each ink individually to UV light. Contrary to what I would have expected, the K7 inks, though they produce a very neutral tone in both negatives on Pictorico and prints on paper, block a lot more light in the UV than in the Visual. For example, a Visual reading of 1.6 turns out to read 2.4 in UV. That difference is as great as what we would normally see with pyro stained negatives.


Sandy

 

[rogein]

The method that Ron outlines in his book using QTR is amazingly powerful. It allows complete control over the ink distribution by the driver, which is something no other method I have seen allows you to do. I spent some time getting my 7800 completely linearized in the driver itself, and the negatives I am getting now are way ahead of anything I have tried to date, on any printer or with any other method. They look and print like in-camera negatives.

Clay,

Can this be done without the benefit of a UV reading densitometer? I bought Ron's book a few months ago, struggled over the QTR chapter and so far got results that are 'fine' but I was hoping for better (ie. less grain using the 4800).

Roger...

 

[clay]

yes, as long as you know how the inks respond in a relative sense. I posted here somewhere the UV ink test for the K3 epson inks in graphical form. The trick is to avoid having the driver put down a low UV transmittance ink dot next to a high UV transmittance ink dot. Basically the black inks do most of the heavy lifting with a little color ink thrown in along the way to assist in enhancing the smoothness of the results.

Clay,

Can this be done without the benefit of a UV reading densitometer? I bought Ron's book a few months ago, struggled over the QTR chapter and so far got results that are 'fine' but I was hoping for better (ie. less grain using the 4800).

Roger...

 

[Ron-san]

Clay,

Can this be done without the benefit of a UV reading densitometer? I bought Ron's book a few months ago, struggled over the QTR chapter and so far got results that are 'fine' but I was hoping for better (ie. less grain using the 4800).

Roger...

Roger--

Here are the relative UV absorbances of the K3 inks as measured on my Xrite 361 T. If the absorbance of matte K ink is set at 100, then C=32.2, M=14.5, and Y=78.3. For the light inks, if LK is set at 100, then LC=40, LM=12.3, and LLK=35.2.

Using the older Ultrachrome inks on my Epson 4000 I went through the exercise of trying to balance the inks so that they were all contributing equally to UV absorbance, and thus hopefully each contributing equally to "hole filling" and making for the smoothest possible tones. The short answer is that you cannot actually do this. The less absorbing inks are so pale that to boost them up to the level of the more absorbing inks means you overload the Pictorico and cause ink puddling.

I finally arrived at a compromise as shown in the attached QTR profile. I balanced the Y and mK inks, since they are the most UV absorbing and then dialled the C and M inks as high as I could without puddling. Similarly I dialled the LC and LM inks as high as I dared, but could not balance them with the LK ink.

I know from actual experiment that using all the inks produces smoother tones than just using mK and LK. But whether the above additional fiddling causes a noticeable improvement is not clear to me.

Cheers, Ron-san

 

[rogein]

Clay, Ron - Thanks for the added info. I haven't given up yet!

Roger...

 

[wiz]

Just one further note, which may speak to the importance Clay mentioned of adjusting each ink individually to UV light. Contrary to what I would have expected, the K7 inks, though they produce a very neutral tone in both negatives on Pictorico and prints on paper, block a lot more light in the UV than in the Visual. For example, a Visual reading of 1.6 turns out to read 2.4 in UV. That difference is as great as what we would normally see with pyro stained negatives.

Well, a carbon pigment particle is just a tiny, opaque "rock", so what you're seeing is either an encapsulating coating over the particle or a UV inhibitor in the ink base that is clear to visible light but stops some UV. In either case, it's something that could change without notice in the future, so you might want to keep an eye on it when you change ink.

 

[sanking]

Well, a carbon pigment particle is just a tiny, opaque "rock", so what you're seeing is either an encapsulating coating over the particle or a UV inhibitor in the ink base that is clear to visible light but stops some UV. In either case, it's something that could change without notice in the future, so you might want to keep an eye on it when you change ink.

As I recall you are experimenting with carbons inks in the cartridges of the Epson R1800. Do you see any blocking in the UV over normal Visual with these inks?

Sandy

 

[sanking]

Ron,

Just wanted to let you know that your prints and files arrived this morning. I don't think it important that your Epson 2200 is not printing well since the purpose of our experiment is to compare the two methods of ink distribution and that will be done better using the same printer, and my 2200 has seen relatively little use since it has only been used for printing digital negatives. Still, I think the limitations of the pt./pd. process are going to mask any superiority of one method over the other, but test will tell for sure.

I would mention that I was in Nashville last weekend for an alternative workshop of a group of old friends, including Sam Wang and some of his former students and a few others, including Mark Nelson of PDN fame. Mark showed some large palladium prints made from digital negatives from the Epson R1800, using the black composite inks and the Epson printer driver with an appropriate curve. This gives a DR of about 2.2 and is suited for developing out palladium using sodium chloride. Mark's prints. which were on COP 320, were without doubt the smoothest toned palladium prints in the upper values that I have ever seen from digital negatives -- in fact it would have been absolutley impossible for me to tell if they had been made with in-camera or digital negatives.

How much of that is due to the R1800, which has a very small picoliter drop and tends to not produce the digital artifcats we see with the 2200, or to Mark's extensive skills with Photoshop I can not say for sure, but the work was very impressive and I find it difficult to imagine that the use of QTR with either Piezography or the Epson inks in composite black could give better results, no matter how carefully one adjusts the ink distribution of each ink. These prints had absolutely no banding or Venetian blinds of any kind and the transition in the high values was stunningly smooth.

Your use of lithium chloride may a small wrench in our plans since I am not sure it is possible to get a maximum denisty of 3.2 with the Piezography ink set. For my work with palladium chloride I look for a maximum density of 2.0 - 2.2. Maybe increasing the ink density will get me to 3.2. If so I do have some lithium chloride and will use it for the comparison.

Sandy

 

[amphoto]

Mark showed some large palladium prints made from digital negatives from the Epson R1800, using the black composite inks and the Epson printer driver with an appropriate curve.

Sandy,

The 'black composite inks' that you refer to, with which Mark got such smooth highlights - were these the Epson black inks (light black, black etc.) or a 3rd party ink set (such as the K7's?).

Cheers,

Angus.

 

[sanking]

Sandy,

The 'black composite inks' that you refer to, with which Mark got such smooth highlights - were these the Epson black inks (light black, black etc.) or a 3rd party ink set (such as the K7's?).

Cheers,

Angus.

Angus,

Epson inks, with the Epson printer driver.

By composite I don't mean just the black inks, but all of the inks, color and black, to form a black composite.

My impression is that the small picoliter size contributes to smoothness, plus the R1800 appears to have a better stepper motor than other Epson printers, with the possible exception of the 3800. I have never heard anyone complain of banding and Venetian blinds with the R1800, as you hear about all the time with the 2200, 2400, 4000, 4800, 9800, etc.

If the Epson R1800 does that well with just the Epson inks and drivers, I have to believe that with a Piezography ink set and QTR you could get even more out of it since you could also print beautiful monochrome prints as well as make digital negatives.

Sandy

 

[sanking]

Ron,

Just a follow-up note to let you know that it will be a few weeks before I am able to complete the Piezograhy/QTR comparision tests we discussed. I had planned to finish the test last week but got tied up with other things, and tomorrow my wife and I are leaving for a two-week trip to British Columbia.

I look forward to doing the tests as soon as we return.

Sandy

 

[Ron-san]

Ron,

Just a follow-up note to let you know that it will be a few weeks before I am able to complete the Piezograhy/QTR comparision tests we discussed. I had planned to finish the test last week but got tied up with other things, and tomorrow my wife and I are leaving for a two-week trip to British Columbia.

I look forward to doing the tests as soon as we return.

Sandy

Sandy-- That is fine. I venture to bet that any differences due to how the inks are used will be completely covered up by differences in printer heads and the generally forgiving nature of the pt/pd process itself. But, if that is the way it comes out, we have will have learned something, no? Have fun in BC.
Cheers, Ron-san