Digital negatives--Basics

[Michael Firstlight]

Forgive me if this isn't the right forum to ask this...

I stopped doing analog film and wet darkroom work around 2000. I did mostly conventional B&W film developing and printing with TriX and Dektol, and a bit of Cibachrome on the color side. After that I went all digital. I now shoot with a 36MP Nikon D800 have good PS skills built up over the last 20 years, and print on an in-house 24" Epson 7880.

Fast forward to present: My interest in shooting film and wet darkroom was rekindled last year and I've recently gotten back into a full analog darkroom process in parallel with my all digital process, though I do scan my 6x7's using a Nikon LS9000 to digitize, adjust, and print to the Epson.

Of late (I am sure very late to the party), I've read something about digital negatives. Please excuse someone with decades of analog experience that left it behind at the turn of the millennium asking a few very basic newbie questions about digital negatives.

Here's what I think I understand so far: Using a particular transparent ink jet printing paper (something like Pictorico TPU100 transparency film), and pecial ink jet printer ink (such as the Selenium Piezography inkset), one can take a digital image, such as one of my D800 files, and use some software such as PiezoDN to do some calibration to the monitor along with determining the minimum and maximum density (sounds a bit involved, but doable), and.....print a negative on any of a variety of compatible ink jet printers. My very basic newbie questions:

1) Ar my assumptions above correct?
2) I assume (ir should be obvious I guess), that the resulting in-jet negatives are usable to print with a conventional enlarger and wet process - either by creating contact prints, or, traditional enlarging (putting the DN into the negative carrier and enlarge from, say, a 6x7 digital negative?
3) Why? What is the benefit? is the resulting quality (tone, sharpness, other) significantly better going from digital file to digital negative to analog wet print? If so, how much better?
4) If it is better, can one do the analog wet printing using conventional silver gelatine materials and chemistry, or does it require higher-end wet process, such as platinum printing, to see the benefits or just the optimal benefits?
5) I assume the printer matters in terms of how good a digital negative is - maybe a 720ppi printer is best?
6) How does the size of the DN relate to analog print quality? that is, if can one make a 13x19 DN and contact print it, vs makign a 6x7 and enlarging it, I would assume its better to make a 13x19 DN over making a 6x7 and enlarging to 13x19. But what if I want to analog print larger - say 16x20 - will a 6x7 DN enlarge well to that size?
7) Does one need to buy the ink and load their own carts? or can one get pre-filled carts of the ink?

My apologies for these very basic questions - I'm an old fart wondering about these new-age tricks. I red several links on the subject and FAQs, but I was still left unclear about the above questions as they tend to assume what might be obvious to those of us that it isn't.

Regards,
Mike

 

[Bob Carnie]

1) Ar my assumptions above correct? Yes - you should be able to create a curve shape with some testing to create an usable negative

2) I assume (ir should be obvious I guess), that the resulting in-jet negatives are usable to print with a conventional enlarger and wet process - either by creating contact prints, or, traditional enlarging (putting the DN into the negative carrier and enlarge from, say, a 6x7 digital negative? No - you cannot put the digital negative and enlarge, Yes you can do contact prints with create sucess when the negative is created to the final size.
LVT Recorders will produce a silver negative that you can indeed put in the enlarger. Think Salgado

3) Why? What is the benefit? is the resulting quality (tone, sharpness, other) significantly better going from digital file to digital negative to analog wet print? If so, how much better?- There are those who claim that they can make good silver prints from a digital inkjet negative... I am not one of those people- I use a Durst Lambda 76 to produce enlarged negatives on Ilford Ortho film and I have had great success with making contact silver prints , but I have not had the same quality of success with inkjet negatives(there are those who make this claim)
The main benefit of digital negatives from your digital cameras is the simple fact that you can use historic wet processes and not limited to inkjets or C prints off big laser printers.

4) If it is better, can one do the analog wet printing using conventional silver gelatine materials and chemistry, or does it require higher-end wet process, such as platinum printing, to see the benefits or just the optimal benefits? I do not think any one way of skinning this cat is any better(other than the sample situation I provided above) but the many options are now open to us is incredible... I still shoot film and make enlarger prints as well scan film and make prints via digital negs, basically the whole gamut is open to you.

5) I assume the printer matters in terms of how good a digital negative is - maybe a 720ppi printer is best? - I can only speak for Epson with K3 inks using quadtone rip and print tool.


6) How does the size of the DN relate to analog print quality? that is, if can one make a 13x19 DN and contact print it, vs makign a 6x7 and enlarging it, I would assume its better to make a 13x19 DN over making a 6x7 and enlarging to 13x19. But what if I want to analog print larger - say 16x20 - will a 6x7 DN enlarge well to that size? - They are equally important and of great qualitiy , the end process basically determines the final output. - (remember the one exception above)

7) Does one need to buy the ink and load their own carts? or can one get pre-filled carts of the ink? - Why complicate your life, I use the inks Epson provides - others methods will vary

 

[David A. Goldfarb]

Thread moved to Digital Negatives forum in the Hybrid section and retitled, since the whole forum is about digital negatives.

 

[MattKing]

Bob's comments are correct.
For clarity, the digital negatives are really only suited to processes that involve contact printing. In many cases, people use them with the traditional processes that respond to UV light - cyanotypes, platinum/palladium, van dyke brown, etc.
The digital negative is printed to the size you want your print to be. Then you coat your paper with the appropriate solution, put it into contact with the digital negative and expose the resulting sandwich to the light the process is sensitive to (which can in a pinch be sunlight, as it contains a fair but variable amount of UV).
The resolution of the available digital printers is less than the resolution of photographic film, so the digital negatives are usually not used with normal photographic paper.
You can actually use enlarged negatives to accomplish these results in an entirely analogue workflow, but the materials for doing so aren't as easily found as in the past, and the analogue approach doesn't offer as extensive a set of controls as the digital process does.
You don't need a special set of inks for digital negatives, but there are special sets that are optimized for them. A friend of mine does both colour prints and digital negatives on the same high end Epson printer. His ink set is the standard one and it costs around $500 CDN.

 

[Bob Carnie]

tks David

 

[nmp]

Here is my 2 cents worth:

1) You have the process about right, but it does not have to be as elaborate as what you are describing. You do not need a special printer with special inks and a special software to do a decent digital neg. Your Epson 7880 with regular ink should work fine. To get at the “correction curve,” which is the goal of all third party DN systems, one can use a simple free software like the ChartThrob. Or Even hand calculations are not that complicated. At least to get started.

2) Most people do only contact printing with a digital negative. I don't believe one can get sufficient resolution with inkjet printing required for enlargement. For example if you want to resolve 300 lpm on an 8X10 print, the required resolution on a 6x7mm negative would come to about 1000 lpm which is somewhat out of the range of what is doable on the current inkjet printers.

3) One obvious benefit is you can make an analog print from a digitally captured image. On the other hand, if you want to make alternative process print like Pt-Pd, the best recourse to make enlarged prints from smaller format capture, be it film or digital, is via digital negative as UV exposure needed to make these prints preclude the use of traditional enlarger. Of course, if you are starting with a film negative, you can make an enlarged inter-negative for this purpose if adept at the traditional darkroom as you seem to be. This would require precise contrast control to fit the subsequent positive process. In the digital negative, the correction curve takes care of this aspect.

4) Nothing is better. Nothing is required. Your choice. Your artistic prerogative.

5) 720 ppi, which is apparently the native resolution of Epsons, should be fine. Canons and HPs are 600 ppi printers, they should be fine too.

6) Once again, making a 6x7 negative on inkjet printer is not advisable. So if you want to make a 13x19 print, make a 13x19 digital negative.

7) No. It is not imperative to buy special inks or cartridges. You can use what you have which ain't shabby. You just have to get the best color to print with to get the maximum opacity.

Good luck!

:Niranjan.

 

[Michael Firstlight]

Thanks all! Great clarifications and informative as always!

Regards,
Mike

 

[LaurentMartin]

Good information for beginners. This is definitely helpful.

 

[Tropper]

This should be a sticky for beginners to read.

 

[Alan9940]

I usually create digital negatives for pt/pd prints, but recently a photographer I know worked on a PS automation process to create digital negatives for silver printing and asked me to try it out. These were primarily intended for contact printing. I found it interesting that his analog prints, based on a negative from an Epson 3880, looked fairly smooth while mine, based on my Epson R2880, looked like the print came from enlarged ISO 3200 film; and, I printed my negative at 720ppi using the highest output resolution of the printer. The only variable was that we output the negatives on to different manufacturer's substrate, but we didn't think that alone would be the reason for this anomaly. My conclusion was that I'd either have to invest in the PiezoDN system or have LVT negs made.

 

[Andrew O'Neill]

We have a clunky old Epson 1400, using cheap replacement ink cartridges from China. My students have been making negatives on cheap also from Chinese, OH material, similar to Pictorico, for cyanotypes and gum prints. I made the curves using Chartthrob... print using QTR.

 

[jim10219]

I've never had any issues making negatives with my Epson 9880. Some people will use a colored ink other than black as their UV blocking ink (probably not necessary for silver gelatin), but I found that I don't get as smooth midtone gradients when going that route, because I don't have any software that can keep the ink ratios consistent throughout the spectrum. I made the curves by hand. It's fairly easy. I just make a 100 step wedge on a digital negative, print it, and then use my scanner and eyedropper tool in PS to measure the output on the final print. Then I build a curve to compensate for any shifts.

I did have an old Epson Stylus 1400 that didn't work for me. The problem I had was I couldn't find a transparency paper that the ink would dry on. It used dye based ink instead of the standard pigment ink. So if you have a dye based printer, you might have to find special transparency paper for it, and not use the standard inkjet transparency paper.

I've also made digital negatives from laser printed transparencies. They work really well too. That was back when I was just trying the processes out, so I never bothered with trying to calibrate anything. I don't think I'd go that route if you're serious though. Laser printers are notoriously bad at printing consistently as they are highly effected by humidity.

 

[nmp]

The only variable was that we output the negatives on to different manufacturer's substrate, but we didn't think that alone would be the reason for this anomaly. My conclusion was that I'd either have to invest in the PiezoDN system or have LVT negs made.

As I understand many who make digital negatives for traditional silver gelatin printing use white film and not clear film like the Pictorico TPU100/TPS100 or equivalent. The white film allows for some softening of the grains that would otherwise show up with the clear film negatives. Is that the difference between the two substrates?

:Niranjan.

 

[Alan9940]

As I understand many who make digital negatives for traditional silver gelatin printing use white film and not clear film like the Pictorico TPU100/TPS100 or equivalent. The white film allows for some softening of the grains that would otherwise show up with the clear film negatives. Is that the difference between the two substrates?

:Niranjan.

No. I used Pictorico and I forget the exact brand he used, but it was a clear film just like TPU100.

 

[nmp]

No. I used Pictorico and I forget the exact brand he used, but it was a clear film just like TPU100.

So much for that theory...

As far as I know Epson R2880 and 3880 both have the same inks. Only major difference is in the max print size. I am not sure I follow the reason you conclude that you need QTR and PiezoDN, is that because he uses those? QTR does allow some funky dithering algorithms that may be beneficial, in addition to being able to combine various inks to smooth out the grains. One can use QTR with the OEM inks as well so perhaps that is something you can consider before converting to PiezoDN.

On the other hand, you can still consider Pictorico white film - something I am thinking of doing myself for Centennial POP which has the same inherent issue, being able to better replicate the ink dot-structure on the negative because of its smooth glossy gelatin surface. The trade-off with white film would be loss of some sharpness, so that would be a consideration.


:Niranjan.

 

[Alan9940]

So much for that theory...

As far as I know Epson R2880 and 3880 both have the same inks. Only major difference is in the max print size. I am not sure I follow the reason you conclude that you need QTR and PiezoDN, is that because he uses those?

Yes, both printers use the same inkset--Ultrachrome K3. That was partly what confused me; also, the R2880 prints at a higher resolution vs the 3880. The only plausible reason I could come up with is that the 3880 has a much larger "professional" print head and, perhaps, has a tighter more concise dither pattern when laying down ink?

No, he didn't use QTR or PiezoDN. He wrote his own PS automation process to generate a step wedge, read it from a scan, then create the necessary curve. It all worked just fine, except my digital negatives looked "grainy." I do use some custom curves and QTR for printing digital negatives for pt/pd printing, but you certainly don't need QTR. I was merely suggesting that, perhaps, Cone's PiezoDN system might be capable of generating good 'nuff digital negs for silver printing; otherwise, one has to send out for a film recorder negative.

 

[nmp]

Yes, both printers use the same inkset--Ultrachrome K3. That was partly what confused me; also, the R2880 prints at a higher resolution vs the 3880. The only plausible reason I could come up with is that the 3880 has a much larger "professional" print head and, perhaps, has a tighter more concise dither pattern when laying down ink?

No, he didn't use QTR or PiezoDN. He wrote his own PS automation process to generate a step wedge, read it from a scan, then create the necessary curve. It all worked just fine, except my digital negatives looked "grainy." I do use some custom curves and QTR for printing digital negatives for pt/pd printing, but you certainly don't need QTR. I was merely suggesting that, perhaps, Cone's PiezoDN system might be capable of generating good 'nuff digital negs for silver printing; otherwise, one has to send out for a film recorder negative.

Another issue I have not delved into yet is that of bit depth. My original files are in 16 bits. For printing I just send them as is to the printer where I guess they are re-sampled based on the specified dpi as well as converted to 8 bits (?) since very few printers are capable of printing 16 bits in its native mode. Could there be a difference in how this whole sequence is done from printer to printer? Does it make a difference if the file is converted to 8 bits first in PS with dithering turned on before sending it out to print. Or re-sampled to the target dpi in PS as well. Add one more to the pile of experiments.....

Speaking of PiezoDN, I have scored myself a refurbished Epson 1430 that I am debating if I should covert to PiezoDN system or just plain Carbon inks. From what I have heard, this printer having much finer droplet size than the newer pigment models might be have some advantage for making digital negatives.

:Niranjan.