Digital Negative Resolution

[tgtaylor]

I've been contemplating trying some of the "alternative" printing methods p- starting out with the Cyanotype.

So armed with a 40% off Borders coupon this weekend, I purchase Digital Negatives: Using Photoshop to Create Digital Negatives for Silver and Alternative Process Printing by Hinkel and Reeder, 2007.

Although I have not yet read it, I am somewhat puzzled by the following statement on page 19:

"...One common critique of the digital negative is that it is not as sharp as a film negative. This is definitely true. Digital negatives can hold one hundred lines per inch of detail (or even a bit more), but film can hold thousands of lines per inch...But the detail of the digital negative is more than sufficient for making very sharp prints when contact printing..."

"One hundred lines per inch" translates to about 4 lines per milimeter. Is a resolution of 4 lines per milimeter truly sufficient for a print?

Thomas

[paulr]

I have no direct experience with digital negs, so this answer is purely theoretical.

The passage you quoted makes me suspicious of the whole book, because it demonstrates that the author doesn't know what sharpness is. If he's conflating sharpness, resolution, and line frequency, then I wonder what other facts he's been sloppy with.

I'd have to know where he's getting his numbers to even evaluate the ideas he's presenting.

I'm also curious to know if he means 100 line pairs per inch, because that's a unit that comes a little closer to having some value.

If that's what he means, and the result is a print that resolves 4 lp/mm, then yes, the result can be an extremely sharp print. But it won't be a print that shows the finest detail when you look very close.

My final comment is that it seems strange that a digital neg would have this kind of limitation. How is it being produced?

[sanking]

When making digital negatives with inkjet printers the resolution of the negative is limited by the printer and the media in the same way that resolution is limited when making prints with the same printer. The only difference between a negative and print is that the negative is inverted and made on a clear film and the print is a postive made on paper. Since the effective resolution of inkjet printers is somewhere between 360 dpi to 720 dpi this puts the maximum possible resolution of a digital negative at between 7 lp/mm and 14 lp/mm, with the first figure much more likely than the second.

A sheet of 4X5" film is likely to contain the equivalent of about 40 lp/mm or more of effective resolution. However, if the negative is scanned with a perfect scanner and the file printed at 4X the resulting resolution will be limited about 10 lp/mm maximum by the film, and perhaps less by the printer and media.

Some loss of resolution in making an alternative print may occur because of paper texture. This is true of processes like pt/pd, kallitype, vandyke, cyanotype, etc. In these cases the limit of resolution is usually the paper, not the negative. Even if you print directly with an 8X10 negative that has the equivalent of 40 lp/mm of resolution the paper will limit the resolution to 10 lp/mm or less because of the texture of the paper.

Sandy King

[paulr]

Is the book about printing the negs on an inkjet printer? That gives me a better idea.

Inkjet prints from a 720 ppi printer contain as much detail as anyone can see with the naked eye (but not with a loupe) and can be subjectively much sharper than a traditionally made enlargement or contact print. I've done enough side by side comparisons with my own 4x5 negs to see this consistently.

I don't know how much you lose from the neg in the contact printing process, but imagine it's not much, and that it can be mostly compensated for with intelligent sharpening of the neg.

You should be able to produce prints that are sharper than what you could produce traditionally, but you'll see the limits of the fine detail if you like to look at prints with a loupe.

[redrockcoulee]

Is the book about printing the negs on an inkjet printer? That gives me a better idea.

Inkjet prints from a 720 ppi printer contain as much detail as anyone can see with the naked eye (but not with a loupe) and can be subjectively much sharper than a traditionally made enlargement or contact print. I've done enough side by side comparisons with my own 4x5 negs to see this consistently.

I don't know how much you lose from the neg in the contact printing process, but imagine it's not much, and that it can be mostly compensated for with intelligent sharpening of the neg.

You should be able to produce prints that are sharper than what you could produce traditionally, but you'll see the limits of the fine detail if you like to look at prints with a loupe.

Yes the book is about printing digital negs on a inkjet, primaryily Epsons.

[Richard M. Coda]

I have seen side by side comparisons of an 8x10 contact print and a print of the same negative scanned and a digital inkjet negative. Contact print wins hands down... the inkjet negative was not even close. Now, if you like platinum/palladium prints then this may be good enough for you, but I am a silver printer and it just doesn't cut it.

I have had negatives (from 35mm to 4x5 to 8x10) drum scanned, did my Photoshop work (basically to salvage a bad negative of a good image) and had them output to new SILVER negatives at Chicago Albumen Works (http://www.albumenworks.com/lvt_prices_working_photogs.htm), and then printed them in my darkroom. These prints are INDISTINGUISHABLE from prints where no digital manipulation was used. CAW can output silver negatives for silver or platinum printing. In fact, I have a friend who did a workshop in Scotland. He has a beautiful nude 4x5 platinum print. He said he can only print this in platinum because it hides the defect and wished he could print it larger but the film was nailed by x-rays on the way over. He showed me a silver contact print and there are three distinct lines. We are having the neg drum scanned and I will photoshop them out. Then we will have a new 11x14 negative made so he can make 11x14 platinum prints.

On my website, the first two images you see are hybrid prints. World Trade Center started out as a 35mm negative with an overblown out sky. I now have an 11x14 negative that I contact print. The Flag started out as a DSLR image (only camera I had with me). I did my Photoshop work to make it a grayscale image and then had a new 4x5 negative made that I enlarge and print traditionally.

[sanking]

I have seen side by side comparisons of an 8x10 contact print and a print of the same negative scanned and a digital inkjet negative. Contact print wins hands down... the inkjet negative was not even close. Now, if you like platinum/palladium prints then this may be good enough for you, but I am a silver printer and it just doesn't cut it.



But your comparison is not relevant to the question of the OP, which was about making digital negatives for alternative printing, not for silver printing.

The point of greater interest is that regardless of the format size of the negative with which you begin, if you scan that negative you can make a print from it via a digital negative that will be as sharp and have as much detail as an inkjet print made with the same printer, subject to the limitation of the paper on which the image is printed. Since the resolution of inkjet prints is beyond the resolution of most young human eyes that turns out to be more than enough resolution for most persons.

It is also important to understand that at some magnification the limit to resolution is is the original negative, not in the media of printing. For example, if you plan to make a print 32X40" in size from a 4X5" negative a print made with an inkjet printer or with a digital negative will have as much resolution as a print of the same size made in the darkroom with an LVT digital negative.

Sandy

[Richard M. Coda]

Sandy:

I was addressing his puzzlement on the statement (from the book)... "One common critique of the digital negative is that it is not as sharp as a film negative." That is 100% true.

If you want a sharp print and have to use a digital negative, the process I use is hands down the winner, IMHO.

Rich

[sanking]

Sandy:

If you want a sharp print and have to use a digital negative, the process I use is hands down the winner, IMHO.

Rich

This may be true with same size contact prints but it is not true when the resolution is limited by the degree of magnification.

Assuming that we start with a 4X5" negative that has 40 lp/mm of resolution, by the time you magnify the print to 8X10 the resolution is reduced to 20 lp/mm, at 16X20 the resolution is 10 lp/mm, and at 32X40 the resolution is 5 lp/mm. As soon as the limit reaches 10 lp/mm a digital negative made from an inkjet printer (or an inkjet print made with the same printer) will have as much detail/resolution as an LVT negative. The LVT negative is potentially capable of higher resolution than the inkjet negative, but the film limits what is actually there.

Sharpness is of course quite subjective, but most digital inkjet prints of 16X20" or larger that I have seen from 4X5 original in-camera negatives are every bit as sharp as silver prints made in the darkroom. Folks who are still highly involved with silver printing may disagree, but work I have seen strongly supports the opinion.

Sandy King

[paulr]

I have seen side by side comparisons of an 8x10 contact print and a print of the same negative scanned and a digital inkjet negative. Contact print wins hands down...

Not in my experience. I have about a dozen negatives that I've printed both contact on gelatin silver, and inkjet at 1:1 with piezography.

In terms of sharpness and clarity, it's no contest. Ink wins. In terms of tonal range and other intangibles, it depends on the image (and the tastes of the viewer).

The caveat is that the inkjet printing system needs to be a good one, and the person doing the printing needs to have an excellent workflow, including a nuanced approach to sharpening. It's a lot more complicated than making a contact print ... simplicity is maybe my favorite advantage of contact printing.

[paulr]

Sandy:

I was addressing his puzzlement on the statement (from the book)... "One common critique of the digital negative is that it is not as sharp as a film negative." That is 100% true.

No it isn't. A traditionally made film negative's sharpness is limited by the materials. A digital negative's sharpness isn't limited.

Maybe you're equating resolution with sharpness? They aren't related, especially when using a digital workflow.

[Darryl Baird]

really interesting topic...

I have been through several digital negative processes over the years and find the output techniques for making digital negatives has evolved and matured far beyond the "good ole days" when making an enlarged negative for Alt-photo printing meant either shooting a good print and developing for contact printing with the correct contrast and density for the printing process (cyanotype, van-dyke, platinum, etc.) OR the two-step process of making an enlarged film positive and contact printing a copy negative ... and might I mention, SOOOOOOO many of those films are "history" now.

Dan Burkholder helped jump-start the digital negative trend back in the early or mid-1990s. I know that Sandy King was a part of that conversation over on the alt-process listserv. Check out the archives for a glimpse of the 90s and all the debates... good, bad, and f***king outrageously ugly from time to time.

The "sharpness" of a enlarged film (or copy) negative is surpassed by a good quality inkjet or imagesetter negative today. I've done it every way that was possible as of two years ago. I stand by that statement with many, many prints.

[PViapiano]

Hmm, without getting the heavy equipment out and over-analyzing everything to death, I have to say that my impressions upon working with both traditionally enlarged negs and inkjet negs for platinum prinitng is that the traditionally enlarged negs have a slight advantage in tone and sharpness.

However, I use the inkjet negs most of the time, because of the time and space involved in making the film negs (a positive has to be made first, dried, and then a negative made...plus everything has to go just right and you have to hit your contrast right on the mark...whew!)

I was just at the Irving Penn exhibit at the Getty, 252 prints in silver and pt/pd. All of the pt/pd were done with trad. enlarged negs and they were amazing prints. Definitely a different feeling than the inkjet neg works I've seen.

I have not used LVT negs, but Linda Butler has used them extensively especially in her China book and the result is fantastic. She prints by enlarging the 4x5 LVT negs as she would any other neg in her enlarger to make silver prints.

I have made inkjet negs for silver contact printing (Ron Reeder has a great QTR profile for this on his site) and for certain subjects they look great, but there's definitely a big limitation there.

[Nathan Potter]

[QUOTE=PViapiano;516642]Hmm, without getting the heavy equipment out and over-analyzing everything to death, I have to say that my impressions upon working with both traditionally enlarged negs and inkjet negs for platinum prinitng is that the traditionally enlarged negs have a slight advantage in tone and sharpness.

However, I use the inkjet negs most of the time, because of the time and space involved in making the film negs (a positive has to be made first, dried, and then a negative made...plus everything has to go just right and you have to hit your contrast right on the mark...whew!)

Why not just do a reversal processing of the first generation enlarged image so that you get a first generation neg (neg 4X5 to neg 11X14, for example). I realize that you'll have to calibrate the exposure and development precisely to duplicate the tonal range but once calibrated you can handle a variety of original negs. Of course as others have intimated you have huge flexibility in working the digital approach.

Nate Potter, Austin TX.

[sanking]

I was just at the Irving Penn exhibit at the Getty, 252 prints in silver and pt/pd. All of the pt/pd were done with trad. enlarged negs and they were amazing prints. Definitely a different feeling than the inkjet neg works I've seen.



Regardless of the issue of image quality comparing prints made with digital negatives to those made with traditional in-camera or darkroom enlarged negatives there is no question but there is a slightly different look. Prints made from digital negatives tend to have a very linear curve while those made from film will generally have a long toe and shoulder, especially with pt/pd which tends to re-enforce the shoe and toe of the film.

BTW, it would be interesting to know when the Penn pt/pd prints you saw at the Gerry were made. I believe that most professionals printing pt/pd for other artists have switched to digital negatives.

Sandy King

[paulr]

Prints made from digital negatives tend to have a very linear curve while those made from film will generally have a long toe and shoulder, especially with pt/pd which tends to re-enforce the shoe and toe of the film.

Don't you have control over this while making a digital negative? Seems you could have as much toe or shoulder as you want.

When I reprinted a body of work digitally (one that I'd previously printed in silver) I found that in many cases the "look" of the silver print worked for the image. So I shaped the curve with a pretty substantial toe and shoulder. Other images worked with a more linnear curve, so I did less shaping.

[sanking]

Don't you have control over this while making a digital negative? Seems you could have as much toe or shoulder as you want.

When I reprinted a body of work digitally (one that I'd previously printed in silver) I found that in many cases the "look" of the silver print worked for the image. So I shaped the curve with a pretty substantial toe and shoulder. Other images worked with a more linnear curve, so I did less shaping.

Sure you can control it. But most people adjust their curves for linearity, not to mimic the look of a pt/pd print made with an in-camera negative. In fact, for me there is nothing sacred about the look because it typically results in shadows and highlights with reduced contrast.

I know that Mark Nelson and Dick Arentz have worked on curves to mimic the pt/pd look but for my own work I create a linear curve and then just adjust the image on the monitor to get what I want.

Sandy King

[paulr]

...but for my own work I create a linear curve and then just adjust the image on the monitor to get what I want.

Sandy King

Right, that's what I mean ... there's no inherent look to the digital neg, at least as far as tonality goes. So you'll often see a very straight looking curve, but this is because the digital neg is capable of looking this way, not because it must.

Same as with a digital print.