[biz-engineer]

As we start to see 4k projectors more and more affordable, I was wondering if anyone already tried to use a 4k digital projector to project the negative of a digital image on traditional dark room negative B&W paper.
I've searched the web for information about using such process, but I've found very little information about it. In one forum, someone tried and claimed to have good results, although he pointed out that the light intensity of the projector was too much and reducing light intensity results in lower image contrast, suggesting use of a ND filter in front of the projector. Has anyone tried that method and what was the return on experience?

[Alex645]

Sorry to be the first response and to say, "no I haven't tried that" but I can see all the 'negatives' and very few positives.

Brand new enlargers with a kit lens like the Beseler Cadet II start at under $400. A new 4K projector like an Optoma starts at $800. Used, enlargers are going to be much cheaper. Replacement bulbs for the Beseler 75W will cost about $3.50 while the Optoma 240W is $150. So cost alone doesn't make sense.

Other issues that would be problematic other than the overkill in lumens include:
a) A digital projector will give you rows and columns of pixels on your print which will look more like a half tone.
b) They produce a lot of heat and the fan will create some vibration and dust.
c) You will need to somehow baffle the lamp vent inlets and outlets from stray light.
d) The heat of the 240W lamp is problematic on the film negative causing it to curve/distort.
e) For accurate timed light, you can't just go from a white to black on a digital projector. The black still has a light output.
f) Digital projector lenses don't have adjustable aperture blades. It would like using an enlarging lens with it's widest aperture, creating depth of focus issues.

Although I think someone could reinvent the enlarger with a digital version that could have some cool modern features, the beauty of the traditional enlarger is its simplicity and ease of maintenance. I teach in a darkroom with 21 enlargers, and many of them are more than 40 years old. The worst ones are the Beseler 67VC. They are a diffusion enlarger with variable contrast that you can dial the contrast. I am constantly fixing the filters getting stuck in the open position and replacing the halogen lamps that have a much shorter life than the cheaper tungsten.

[Wasp]

I don't think that film negatives is part of the plan. The idea is to expose a digital image onto photographic paper that is then developed in the normal way.

Other problems identified seems valid, especially stray light. I guess one could put the projector into a wooden box or something with just the lens sticking out.

The proper way to do it is with one of these, but they are expensive.

Products - De Vere Enlargers

[photoptimist]

In theory it should work well for printing up to about 8x12 (based on Nyquist and a 6 line-pairs-per-mm resolution of printing paper) although the degradation at 16x24 might not be too bad.

I'd think that the biggest challenges would come from getting a corner-to-corner in-focus image at the very close working distance. Can the projector close-focus to form a sharp 8x12 image? Perhaps adding a +1 diopter close-up filter might do the trick but will it be corner-to-corner sharp?

I'd also think about how to add a Waterhouse stop inside the lens of the projector. Stopping down to f/8 would both reduce the light levels and sharpen the image. The only tricky bit is in making an aperture disk that can withstand the non-negligible heat it must absorb from the projector bulb.

[Alex645]

I don't think that film negatives is part of the plan. The idea is to expose a digital image onto photographic paper that is then developed in the normal way.
The proper way to do it is with one of these, but they are expensive.
Products - De Vere Enlargers

Is this what the OP was referring to? That would be interesting to hear from anyone having done this.

I wonder how they get around the issue of the pixel dot pattern from the sensor? OLPF or AA filter? But then you'd lose sharpness.

If my goal were to take a digital image and print it on monochrome gelatin silver paper, I'd probably inverse my digital image and then print it on an inkjet paper with specialized transparency film like this one here:

PermaJetUSA Digital Negative Film 165 Specialist Inkjet APJ52121

Then you could make a contact print from that. Not sure if the resolution is high enough from an inkjet printer to enlarge a 4x5" or 8x10" version.

[biz-engineer]

I guess one could put the projector into a wooden box or something with just the lens sticking out.

That's what I was thinking. + using a ND filter + some kind of manual shutter.

---------- Post added 15-04-20 at 16:13 ----------

In theory it should work well for printing up to about 8x12 (based on Nyquist and a 6 line-pairs-per-mm resolution of printing paper) although the degradation at 16x24 might not be too bad.

I was thinking it could be fun to do, just buying some ilford photo paper, chemical kit and a few cheap plastic trays. With regards to resolution I am not sure how it would come out with 4K... 4K good sharp pixels are not the same as 4K blurred pixels. The reason I'm hesitating to do the experiment is that I haven't bought the 4K projector, but I was thinking of buying one (not for that experiment). If I would already have the projector, I'd have ordered an Ilford kit already to try it out.

---------- Post added 15-04-20 at 16:24 ----------

The proper way to do it is with one of these, but they are expensive.Products - De Vere Enlargers

I see. It seems to work like an LCD projector, but designed specifically for photographic enlargement. Limited to 17Mpixels / 24 inches long side.
This idea of using a projector came to my mind when I was thinking of a way to make photo prints without the upfront cost and cost of ownership of inkjet printers, and without having to wait two week to get prints from outsourced photo lab. The advantage of using a conventional projector is that the projector can be used for photo / video projection, and occasionally used for making a few prints.

---------- Post added 15-04-20 at 16:29 ----------

... Other option would be to use a monitor, stick darkroom paper directly on the display and switch the display on/off for paper exposure.

[photoptimist]

I wonder how they get around the issue of the pixel dot pattern from the sensor? OLPF or AA filter? But then you'd lose sharpness.

Actually, if one makes a Waterhouse stop with an aperture that is shaped like the projector's pixel tiling geometry, then a slight amount of defocusing creates the perfect bokeh-blur to fill in any gaps between projector pixels.

[Bob 256]

At one time, Panasonic was utilizing an apodizing filter in their projectors which greatly reduced the "screen door" effect but that was in HD projectors - not really sure you'd need that in a UHD since the pattern is so small but as photoptimist pointed out, even with UHD, you'd be limited to 7.2 x 12" size to meet 300dpi resolution on the paper. You can get scanned 300dpi prints (from digital files) for a lot less money and work (those print services provide the developing of the print paper and use laser scanners which provide excellent quality scans to sizes well beyond 7.2 x 12"). You might also run into issues with gamma since the image from a projector is gamma corrected differently than that required for a print exposure. I would guess that you might be looking at too much contrast using a projector rather than not enough (although many LCD projectors lack contrast to begin with). You will also have to come up with a shutter mechanism because it's impractical to switch most projectors on and off for short intervals. It's an interesting concept if you want to do your own digital/chemical prints but I'd pass because of the requirement for chemical development and what that entails versus the availability of good print services.

[Wasp]

The easiest way to expose a digital image onto photographic paper is with a contact print.The print will be the same size as the original. Print the (negative) image with an inkjet printer. Printing on a transparency will probably give the best results, but ordinary paper will work as well. Place this page onto photographic paper in the dark. Switch light suitable source on and off - some trial and error will be needed to get this right. Develop in the usual way.

---------- Post added 2020-04-15 at 17:57 ----------

Eureka! It turns out that one can stick a mobile phone into an old school enlarger and expose photographic paper. The limits are the resolution of the phone screen and the size of the film negative that the enlarger was designed for. Most enlargers max out on medium format, i.e. about 6x7cm. Here is a video on how it is done.

You Tube

You Tube

If you can get your hands on a 4x5 or 8x10 enlarger, you can use a tablet instead of a phone.

[biz-engineer]

Printing on a transparency will probably give the best results, but ordinary paper will work as well.

Sure. But if I already have to have a printed of the size of the print I want to do, then I can print on paper directly. I've found this interesting resources here (Easy Digital Negatives | Peter Mrhar) for digital negative printing ( keeping it in mind for now).

This guy here is using a mobile phone and camera as enlarger:

You Tube

You Tube

[StiffLegged]

All this talk of enlarging brings back so many happy, red-illuminated, memories. Yesterday my daughter was looking through old photo albums of ours which included B&W prints of forty years ago. Printing your images on photo paper is lots of fun!

[stevebrot]

The main problem is low native resolution from even a 4k projector in conjunction with the beefy support needed to position the projector. There are also issues with the optics being adequate to a task. Color balance is a pain if doing color and there is always the matter of large enough trays or drum processors. It is probably easier to simply print what we can to inkjet at home and have larger prints done by a commercial shop.


Steve

[stevebrot]

Eureka! It turns out that one can stick a mobile phone into an old school enlarger and expose photographic paper. The limits are the resolution of the phone screen and the size of the film negative that the enlarger was designed for. Most enlargers max out on medium format, i.e. about 6x7cm. Here is a video on how it is done.

I own the same model (LPL 670MXL) enlarger as in the video. They still make them but the prices are very high (~$5600 USD) now new.


Steve

[fs999]

You will also have problems with the multigrade filters needed for contrast adjustments...

[Bob 256]

You will also have problems with the multigrade filters needed for contrast adjustments...

I think the previous references are to color printing but you bring an interesting point that B&W prints can be done this way too (with the same resolution limits withstanding), and the cell-phone/tablet/enlarger combinations would really lend themselves to the task given the advances in screen resolution they have today.

Color adjustments are best done in the digital realm prior to exposure. There's no reason to have to deal with color compensating filters when all that can be done digitally. Likewise, adjusting the blue/yellow content of a B&W digital negative image will work for multi-contrast papers if they are used.

The main problem dealing with an enlarger is it forces one to use a smaller screen device (unless an 8x10 enlarger is available) and that tends to lead to a lower resolution result. Using a larger higher resolution screen requires a large format enlarger which kind of defeats the purpose.

Too bad someone doesn't offer a drop-in laser scanner module for an enlarger which could provide high resolution chem prints from digital files (using a 35mm enlarger).