Home-darkroom silver-gelatin prints from digital images

Started Apr 24, 2016 | Discussions
OP tim baker Forum Member • Posts: 79
Re: Home-darkroom silver-gelatin prints from digital images

Don:

There's an outfit presently doing film recordings of digital images. If anyone is interested I'll find the link and post it.

Assuming the finished print result is satisfactory, that route does involve an extra step, an extra generation removed from the original file, extra expense, and wait time. With the process at center here you can have prints in your hand minutes after shooting.

One advantage of the film recording route is that there's no need to buy the fairly expensive 4k or 5k computer needed.

Tim

Laser JoJo New Member • Posts: 10
Re: Home-darkroom silver-gelatin prints from digital images

Tim, I first wrote an answer in a thread also opened by you:

http://www.dpreview.com/forums/thread/3995462#forum-post-57764399

There you can see my setup. The cover of my enlarger was opened to show the parts inside. Naturally I never could do this if I would not work with such technology in my business. You need some years of experience with lasers and optics as well as electronics and software programming. I just posted this because the question was "Is it possible?" Yes, I did it.

Nobody wants to bring people back into darkroom, if they feel more comfortable in front of the PC.

But printing pictures this way on photographic paper is not old fashioned. It is still done by a similar way today in big labs for mass-printing. It will not completely be replaced by inkjet printing in the near future. Photographic LCD- or Laserprinting is much more reliable, less moving parts, no ink, much faster and produce outstanding quality.

Mine as well as your setup allow people who still have their darkroom alive printing their digital pictures.

Laser JoJo New Member • Posts: 10
Re: Home-darkroom silver-gelatin prints from digital images

tim baker wrote:

Let's say, by the trial and error if no other way, you adjust screen color so that paper does see the image just as the eye does. Note that new color profile and activate it for each image when making color prints. This should allow color prints from a given screen then????

Not sure how you want to adjust screen color.

Color paper has about 30-50 times sensitivity for blue compared to red. For example, for doing balanced color prints, the power of my lasers are:

2.5 microwatts for red, 0.15 microwatts for green and 0.07 microwatts for blue.

You never can do this with monitor settings or settings of your digital file. If you reduce your blue amount directly in the picture by 25, you have 10 steps left to control the blue color itself (= the yellow color on paper). Not enough. What you must do is adding magenta and yellow filters in front of your camera lens, matching exactly to the light of your monitor screen.

Developing color paper is not the same easy like b/w. You need higher temperature and you must do it in nearly complete darkness.

OP tim baker Forum Member • Posts: 79
Re: Home-darkroom silver-gelatin prints from digital images

Jojo:

Thanks for the useful facts and figures.

It would be good to avoid the option of correcting the blue and green with filters on the taking lens; that would make the image in Photoshop look too alien to allow accurate minor corrections, needed for almost all images if best possible prints are wanted.

Instead, any reason not to do the filtering before reaching or after leaving the projector lens? A bit longer exposure time, but quality color prints could flow from this rig

I'm familiar with printing color, but am red/green color blind, and got tired of the laughter.

Tim

OP tim baker Forum Member • Posts: 79
Re: Home-darkroom silver-gelatin prints from digital images

Jojo:

That is a sweet rig!

For an 8x10 it's projecting about 400 what per inch? I think you said not hard dots, but something less crisp-edged? At 8/10 the image must be very sharp to the eye though, yes?

"But printing pictures this way on photographic paper is not old fashioned... It will not completely be replaced by inkjet printing in the near future. Photographic LCD- or Laserprinting is much more reliable, less moving parts, no ink, much faster and produce outstanding quality... Mine as well as your setup allow people who still have their darkroom alive printing their digital pictures."

This is so sensible the notion will catch on soon, at some level. I've just started a meetup group, here in LA, for people interested in making silver prints from digital. I'll give printing demonstrations and show folks how to put rigs together, and as importantly, show just how preposterously simple a home darkroom can be. I aim to start a chat site for involved folks to share information. Who knows, home printing of digital pix might become a thing.

Tim

Laser JoJo New Member • Posts: 10
Re: Home-darkroom silver-gelatin prints from digital images

Sorry for the misunderstanding: I meant the filter in front of the lens of your projector or enlarger. For me, this is a kind of camera using paper instead of film.;-)

The original image must not be turned to red because of reducing the color information of G and B.

For an 8x10 it's projecting about 400 what per inch? I think you said not hard dots, but something less crisp-edged? At 8/10 the image must be very sharp to the eye though, yes?

Yes,  sharp  enough. I would not spend money and time in such a device for printig "unsharp" photos.

Most people today never see pictures >150 DPI because they watch all pictures on the PC-screen only. Even your 5K display has not more than 220 DPI when watching pictures on it. There is no need to print more, except you want to judge print quality by use of a microscope. Nobody will press his nose to the glass of your Retina 5K to count the pixels.

Resolution is just ONE factor. It is like with DSLRs: It is not just the number of megapixel.

OP tim baker Forum Member • Posts: 79
Re: Home-darkroom silver-gelatin prints from digital images

JoJo:

"For me, this is a kind of camera using paper instead of film."
That's exactly it.

First tests with this idea used a 1080 monitor, borderless 5x7s having 216dpi resolution. When shown to civilians I'd ask it they could see the dots that make up the picture. Most, understandably, had no idea what I meant, assuming the print was conventional. If asked to look very closely for dots a high % failed to see them. Anything above 200dpi is fully satisfactory to anyone not intentionally dot sleuthing.

With your system, at what size image can dots be seen by a casual observer?
What's to prevent you from producing some same-resolution version of it in commercial numbers?

So if the correct g/b filtering is placed between projector lens and paper a monitor can generated color prints color-identical to those from a standard enlarger. True?

Are you familiar with the old Widelux cameras? https://en.wikipedia.org/wiki/Widelux Using the same principles, it seems that the projected resolution of a monitor can be doubled or tripled--depending on the geometry of the monitor--a 4k generating a pure 11 or 12k print image. Possibly adaptable to your system also. Once present dust has settled I'll forward how-to ideas, if interested.

Tim

Laser JoJo New Member • Posts: 10
Re: Home-darkroom silver-gelatin prints from digital images
Anything above 200dpi is fully satisfactory to anyone not intentionally dot sleuthing.

I know. With normal b/w or even color pictures, you will not see Pixels above 200dpi.  Even professional lab-printers do between 270 and 400dpi. But when printing graphics or text, you can see steps. For example, if you make a thin round frame around a round picture, you could see pixels. Have you ever tried to print graphics?

With your system, at what size image can dots be seen by a casual observer?
What's to prevent you from producing some same-resolution version of it in commercial numbers?

Because my system has an unsharp dot, you cannot see the boundaries of the dots. What happens is that the picture seems more unsharp. When printing 50x60cm  which gives maximum 173dpi, you can see that edges are unsharp. But you cannot see pixels.  My dots flow together, so you cannot see them as individual dots. The drawback is that my effective resolution is a bit lower than the theoretical. Edges are not knive-sharp. But the advantage is that even large prints don't show pixel-artefacts.

The setup is sensitive. There are precise aligned parts. It would be possible to build commercial but the main problem is shipping and maintenance. My current setup has the problem of de-alignement when shaking, for example on transport.  Also if some part will be defective, somebody must align and calibrate the thing after repair. This cannot be done by hobbyist.  I did not spend much time and energy in making this thing bulletproof. Also there are some details I must solve first for making it more easy to use.

So if the correct g/b filtering is placed between projector lens and paper a monitor can generated color prints color-identical to those from a standard enlarger. True?

Yes, with filtering you could try this. As a starting point I would use a blank (unexposed) part of a color negative plus 30 magenta and 50 yellow. I am not sure if the quality would be the same like a standard enlarger (but never say never). You probably will not get the full color saturation. An LCD is not red or green or blue pixels. It is a striped pixel, where each color uses just 30% of the pixel. So when you expose a full red area, you really expose just 30% or less with red. The rest is black (white on your paper). So your color saturation of the cyan layer on the paper is just 30% cyan + 70% white which cannot give you 100% cyan. This was a reason I stopped tests with LCD. The colors were not just off, they were also washed out and low contrast.

Color paper RA-4 cannot be contrast controlled, so it is a real challenge to match the contrast of the LCD to the contrast of color paper.

My system does not have this problem, because my dots are 100% filled with each color.

Are you familiar with the old Widelux cameras? https://en.wikipedia.org/wiki/Widelux

I don't think about increasing resolution at the moment.

Laser JoJo New Member • Posts: 10
Re: Home-darkroom silver-gelatin prints from digital images

Test pattern on RA-4 paper exposed with 200dpi. You can see the unsharp shape of the printed elements.

OP tim baker Forum Member • Posts: 79
Re: Home-darkroom silver-gelatin prints from digital images

Jojo:

I've got an old laser printer. Let's say I tell it to print a photo, and as it begins to, I sneakily remove the photo conductive drum et al and feed a sheet of photosensitive print paper through where the photo drum surface rested, then develop the print. First guess is that this would work perfectly if the laser intensity matched the sensitivity of the paper. Any thoughts?

Tim

James Larsen
James Larsen Senior Member • Posts: 4,497
Re: Home-darkroom silver-gelatin prints from digital images

Sounds interesting.

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Laser JoJo New Member • Posts: 10
Re: Home-darkroom silver-gelatin prints from digital images

tim baker wrote:

Jojo:

I've got an old laser printer. Let's say.....

I thought about this in the past. There are some problems with a laserprinter:

1. When opening any cover or removing drum, it will stop. So have to bridge all sensors.

2. The high voltage inside can kill you. So you have to remove the HV-parts (+ bridging sensors which watch HV).

3. The Laser inside is Infrared 780nm. It will not expose your b/w and not my color paper at all. You have to replace the laser against a visible one.

4. The paper path around the photconductor drum is NOT the same like the path from the laser scanner unit to the photo drum. So you have to create a new paper path.

5. The printer can only print digital and no grey shades. So any halftone picture will be converted to raster image.

6. The fuser unit will melt your emulsion of the paper and the PE-coating and will glue all together to the transport rollers. So you have to sabotage the fuser unit by cutting the heater lamp + faking possible sensor signals.

To do this, you need at least a complete service manual with all schematics of the cables, sensors and circuits. And you need high knowledge in electronics. Most parts of a printer are not documented (for example the laser module). You will have no idea how to change the IR-diode against a blue one.  And you must align the laser focus.  And last, all the safety functions and sensors must be simulated. Nobody knows how they do it. Some printers require that the paper moves over n-sensors in a specific time frame. So the sensors must be switched in a special sequence. Just blocking them gives a paper jam error. Others measure voltages or temperatures (fuser unit), so voltage signals must be simulated.

I guess this all will take a year - if somebody has no job .;-)

There was a guy using an LED-head instead of the printer head of an inkjet printer.

http://1.f.ix.de/make/imgs/76/9/4/3/7/0/8/524cca0d87684a3b.jpeg

But I don't think that the results were near that what we call a photographic image. He wrote that his pixel size was 1x1mm, so 25dpi at all.:-P

OP tim baker Forum Member • Posts: 79
Re: Home-darkroom silver-gelatin prints from digital images

I've started a meetup group here in LA for people interested in digital to darkroom prints.

I'll be giving a demonstration of the process in a few days. If you're in or near LA, or know anyone here who might be interested, contact me for day, time and details.

http://www.meetup.com/the-los-angeles-digital-meets-the-darkroom-group/

Tim

Laser JoJo New Member • Posts: 10
Re: Home-darkroom silver-gelatin prints from digital images

Whow! Seems that you need a larger darkroom.

OP tim baker Forum Member • Posts: 79
Re: Home-darkroom silver-gelatin prints from digital images

Jojo:

Thanks for the solid info, the first few yards:

I'm betting there's a way to remove all but the [new] laser and fool it into thinking all is as it should be and happily lase away while the silver paper is fed through the target area at just the right pace.

It's good to begin projects like this naively certain it not only can happen but will be quick and easy. This gets you several yards into the bog before the reality hits that it's not easy and might not be possible; but by that time you've come far enough to see farther than you could have from the shore of the bog, and that draws you on further, and so on, till eventually, nearly spent, you stumble free up the other shore, project successful.

Tim

OP tim baker Forum Member • Posts: 79
Re: Home-darkroom silver-gelatin prints from digital images

I'm prepping to give a meetup group demonstration of this digital to silver printing method. Apart from showing the rig I routinely use, to entice members into trying this themselves, I want to show just how simple and inexpensive it can be to set up. So I kept track of all expenses involved in making a bare-bones version to show members.

Item -- cost:

Cardboard box -- Free
One lens from a 99-cent store pair of +3 eyeglasses. -- 75-cents
Tape -- 10-cents
F-30 hole in plastic cap -- free

Total cost for the Huggyflex* Mark 1: 85-cents [*Huggies diapers box]

The prints aren't quite as sharp as versions made with a process lens, but they're mindblowingly good, considering. An F-30 hole was cut in a plastic cap to place over the lens during exposure. This way reduces aberrations inherent in a single-element lens, but enough linger at the corners and edges to impart the Holga effect, quite appealing at times, and nice to have as an options. At f60 or so almost all softness is gone, the print quite acceptable as a standard print to most eyes. Exposure time climbs to a couple of minutes though. Yell if you'd like to put something like this together yourself and I'll email drawings and how-to.

Tim

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Tim Baker

OP tim baker Forum Member • Posts: 79
Re: Home-darkroom silver-gelatin prints from digital images

The digital enlarger demonstration happened last night. A couple of those attending were long-time film-darkroom guys, a couple had dabbled in darkrooms. The rest were digital-only shooters, most aware of the value of silver prints though. I began by showing them a 5x7 made two days ago with the Huggieflex Mark-1--a Huggies Diaper box with one lens from a pair of 99-cent store 3X eyeglasses, and an f-48 iris--a quarter-inch hole in the black plastic lid of a tennis ball container. The photo was brilliant and sharp, with the slightest Holga softness in the corners no one noticed. They were impressed with the photo, so I explained that it was made with an enlarger just made at a total cost of 85-cent. I showed them the 'Huggieflex' and how it operated. Then an 8x10 of the same shot made with a process lens which was cut-your-fingers sharp. Then how the 'adult' enlarger operated. We made a few prints, including a couple that members had sent for me to prep for the demo. One member had a $800 ipad pro, with 2048 vertical resolution. He brought a negative image up on the screen and we made an 8x10 of it... and it was SHARP! The ipad pro is fully ok as a negative source for 8x10s and a bit beyond. -- Everyone got that the prints were as good as anyone would want, that the enlargers were simple and cheap to make, that the three-tray developing setup was simple and convenient, that the process had real value, and several seemed eager to set up to do their own printing. One film guy said he would simply load his 8x10 camera with paper, etc. I'll likely do demos every couple of weeks, the hope being that the fact will spread that traditional silver gelatin wet-darkroom prints can now be made inexpensively and at home. Tim

ozepa New Member • Posts: 1
Re: Home-darkroom silver-gelatin prints from digital images

Hi, thanks for making this info available.  I just started to research how to do it.  I did Silver Gelatin Prints for 15 years, but switched to digital 12 years ago.  I want to start to print in the darkroom again.  How could I get that info?

Techo Veteran Member • Posts: 3,628
Re: Home-darkroom silver-gelatin prints from digital images

Just found this thread. That was my first thought too. I had done b/w dark room contact prints from digital files printed to 8.5"x11" transparency paper via an inkjet printer.  Next I'd like to try this with an enlarger and print to 16x20. I'd imagine producing color darkroom prints would be a tougher/different ball game.

szhane New Member • Posts: 1
Re: Home-darkroom silver-gelatin prints from digital images

Tim , I just read this forum topic on silver gelatin prints from digital images.

Could you please email me the specifics. szhane@gmail.com

Thank you,

szhane.

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