DIY 31 Megapixel Enlarger

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koraks

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You have to pay attention to developer age, how many hours ago it was mixed, how many prints have been made, developer temperature etc.

Not really since print development typically goes to completion. This means that whatever effects aging developer has, are mostly on curve shape and not so much absolute sensitivity. The implication is that working with aging developer would necessitate (if anything) adjustment of your calibration curve, not so much exposure!

using 'factorial development'

That'll work fine and avoid most problems. Exposure can remain unchanged.

Exposure can be 'calibrated' using some kind of light metering device acting on base board level; this can be a regular light meter, lux meter, a fancy enlarging meter etc. Take your pick.
 
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Here is a selection of 36x48" images printed using the 16k LCD as a negative. The sharpness is quite good (there are around 235 pixels per inch along the long edge, and 172 pixels per inch along the short edge; the image uses an 11264 x 6224 pixel area of the display). With enlargements of this size (just under 8x enlargement) and viewing distances of less than a foot, the LCD pixel circuitry becomes visible, but further than that it is invisible. Every three or four pixels there is a small opaque bit of circuitry which shows up in the print as a tiny dot lighter than the surrounding image. They are very small, and impercievable at any reasonable viewing distance, but I am working on ways to hide them. I am currently testing an assortment of cinema soften and blur effect filters with that goal. So far I've found that Tiffen's Soft/FX filter does a good job of reducing sharpness without a reduction in contrast, but I have yet to narrow down which strength will hide the dots without also creating a meaningful loss of resolution. Cine filters are irritatingly expensive. These prints are on Bergger CB Semi Gloss paper, and I've also noticed that this paper (perhaps because it is warmtone, or maybe because of Bergger's recipes) is slightly less sharp than my standard Ilford MGFB glossy. it isn't a loss of sharpness which would be noticable with anything other than a high definition resolution target, but it has the result of making the dots slightly less apparent.
IMG_8495.jpg
IMG_8496.jpg
IMG_8497.jpg
IMG_8498.jpg
IMG_8499.jpg
IMG_8500.jpg
IMG_8501.jpg
 

AndrewBurns

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Here is a selection of 36x48" images printed using the 16k LCD as a negative. The sharpness is quite good (there are around 235 pixels per inch along the long edge, and 172 pixels per inch along the short edge; the image uses an 11264 x 6224 pixel area of the display). With enlargements of this size (just under 8x enlargement) and viewing distances of less than a foot, the LCD pixel circuitry becomes visible, but further than that it is invisible. Every three or four pixels there is a small opaque bit of circuitry which shows up in the print as a tiny dot lighter than the surrounding image. They are very small, and impercievable at any reasonable viewing distance, but I am working on ways to hide them. I am currently testing an assortment of cinema soften and blur effect filters with that goal. So far I've found that Tiffen's Soft/FX filter does a good job of reducing sharpness without a reduction in contrast, but I have yet to narrow down which strength will hide the dots without also creating a meaningful loss of resolution. Cine filters are irritatingly expensive. These prints are on Bergger CB Semi Gloss paper, and I've also noticed that this paper (perhaps because it is warmtone, or maybe because of Bergger's recipes) is slightly less sharp than my standard Ilford MGFB glossy. it isn't a loss of sharpness which would be noticable with anything other than a high definition resolution target, but it has the result of making the dots slightly less apparent.

Very cool, good to see some properly large prints being demonstrated using digital negatives. One option you might have to eliminate the slightly lighter pixels is to apply an inverse mask to the image being projected, I do a similar thing with my UV contact printing setup to eliminate any uneven exposure effects from the light source (which is very uneven). The technique is used a lot in scientific imaging, called flat-field correction. In your case if for example you know that every third pixel you get one pixel with slightly lower transmission (resulting in a lighter spot on the print) you can compensate by making every other pixel slightly darker, so that the final projection is perfectly even. Sure, this has the unwanted effect of slightly increasing your exposure time as you're making the LCD more opaque on average, but they would be even exposures.
 
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Here is a view through the grain magnifier of the pixel array. It is not actually the pixel itself which is darker, but a small diamond shape which repeats every 9 pixels in a row, or in approximately a 3x3 grid. even on the big prints, I'd say each dot is no more than 0.2 millimeters in diameter, they really are tiny.

You're idea is interesting, but I'm not sure if it would be compatible with my software which currently drives the display. perhaps if I generated an image file in photoshop with slightly brighter pixels around the dots, I could reprogram the software to overlay it on the output files. I may explore that route if the analog filter path doesn't lead anywhere.
IMG_8322.jpg
 

AndrewBurns

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Yeah that's basically what I do, I have a python script that I use to pre-process my image (because I use a raspberry pi to control my screen). The script flips, inverts, applies my cyanotype adjustment curve, applies the flat field correction mask, compresses the RGB channels for the monochrome screen and saves the resulting image as a PNG. Then I transfer the modified PNG image to the raspberry pi and I have another simple script on there that just displays the image full-screen and turns on the UV light for the correct length of time.
 

noiva

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Amsterdam
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Yeah that's basically what I do, I have a python script that I use to pre-process my image (because I use a raspberry pi to control my screen). The script flips, inverts, applies my cyanotype adjustment curve, applies the flat field correction mask, compresses the RGB channels for the monochrome screen and saves the resulting image as a PNG. Then I transfer the modified PNG image to the raspberry pi and I have another simple script on there that just displays the image full-screen and turns on the UV light for the correct length of time.
Do you have the source code accessible on a Github repository by chance? I would be interested in this and it could be a nice community project to get a repository going with all the resources
 

AndrewBurns

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Do you have the source code accessible on a Github repository by chance? I would be interested in this and it could be a nice community project to get a repository going with all the resources

No I don't, and my code is pretty trash because it's just something I force into doing whatever I need to do at any given time, but I could look at uploading it sometime this weekend. 90% of my effort was made trying to split the image into multiple tiles when I was trying to tile multiple exposures into a single larger print, but nobody would need to use that stuff. The stuff people might actually want to use is very simple really.
 

Carnie Bob

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Toronto , Ont Canada
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Here is a selection of 36x48" images printed using the 16k LCD as a negative. The sharpness is quite good (there are around 235 pixels per inch along the long edge, and 172 pixels per inch along the short edge; the image uses an 11264 x 6224 pixel area of the display). With enlargements of this size (just under 8x enlargement) and viewing distances of less than a foot, the LCD pixel circuitry becomes visible, but further than that it is invisible. Every three or four pixels there is a small opaque bit of circuitry which shows up in the print as a tiny dot lighter than the surrounding image. They are very small, and impercievable at any reasonable viewing distance, but I am working on ways to hide them. I am currently testing an assortment of cinema soften and blur effect filters with that goal. So far I've found that Tiffen's Soft/FX filter does a good job of reducing sharpness without a reduction in contrast, but I have yet to narrow down which strength will hide the dots without also creating a meaningful loss of resolution. Cine filters are irritatingly expensive. These prints are on Bergger CB Semi Gloss paper, and I've also noticed that this paper (perhaps because it is warmtone, or maybe because of Bergger's recipes) is slightly less sharp than my standard Ilford MGFB glossy. it isn't a loss of sharpness which would be noticable with anything other than a high definition resolution target, but it has the result of making the dots slightly less apparent.
View attachment 396452 View attachment 396453 View attachment 396454 View attachment 396455 View attachment 396456 View attachment 396457 View attachment 396458

f
Here is a selection of 36x48" images printed using the 16k LCD as a negative. The sharpness is quite good (there are around 235 pixels per inch along the long edge, and 172 pixels per inch along the short edge; the image uses an 11264 x 6224 pixel area of the display). With enlargements of this size (just under 8x enlargement) and viewing distances of less than a foot, the LCD pixel circuitry becomes visible, but further than that it is invisible. Every three or four pixels there is a small opaque bit of circuitry which shows up in the print as a tiny dot lighter than the surrounding image. They are very small, and impercievable at any reasonable viewing distance, but I am working on ways to hide them. I am currently testing an assortment of cinema soften and blur effect filters with that goal. So far I've found that Tiffen's Soft/FX filter does a good job of reducing sharpness without a reduction in contrast, but I have yet to narrow down which strength will hide the dots without also creating a meaningful loss of resolution. Cine filters are irritatingly expensive. These prints are on Bergger CB Semi Gloss paper, and I've also noticed that this paper (perhaps because it is warmtone, or maybe because of Bergger's recipes) is slightly less sharp than my standard Ilford MGFB glossy. it isn't a loss of sharpness which would be noticable with anything other than a high definition resolution target, but it has the result of making the dots slightly less apparent.
View attachment 396452 View attachment 396453 View attachment 396454 View attachment 396455 View attachment 396456 View attachment 396457 View attachment 396458

36 x 48 inches? or cm - these are impressive either way.
 
Joined
Nov 20, 2020
Messages
93
Location
Western Massachusetts
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8x10 Format
f


36 x 48 inches? or cm - these are impressive either way.

36x48 inches. I don't think I would have made them this big if I was enlarging from film negatives- all the paper needed to get to a final print would be too pricey, but with this system I was able to make 10 prints in one weekend without any test strips or work prints prior to printing the finals.
 

Carnie Bob

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Joined
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Messages
330
Location
Toronto , Ont Canada
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4x5 Format
36x48 inches. I don't think I would have made them this big if I was enlarging from film negatives- all the paper needed to get to a final print would be too pricey, but with this system I was able to make 10 prints in one weekend without any test strips or work prints prior to printing the finals.

Well I would say remarkable work , I do make 30 x 40 inch digital negs and 30 x 40 enlarger prints for silver work and can say what an incredible achievement. I was making Lambda murals on Agfa Classic in 2002 and the results were incredible, but the machine was 250 thousand dollars and for over 16 years I lugged it around with me until I started making digital inkjet negs which allowed us to drop the Lambda.
At what magnification do you start seeing abborations, these prints look pretty amazing, I would love to see one in person .
 
Joined
Nov 20, 2020
Messages
93
Location
Western Massachusetts
Format
8x10 Format
Well I would say remarkable work , I do make 30 x 40 inch digital negs and 30 x 40 enlarger prints for silver work and can say what an incredible achievement. I was making Lambda murals on Agfa Classic in 2002 and the results were incredible, but the machine was 250 thousand dollars and for over 16 years I lugged it around with me until I started making digital inkjet negs which allowed us to drop the Lambda.
At what magnification do you start seeing abborations, these prints look pretty amazing, I would love to see one in person .

There are abberations visible in these prints (8x magnification) but at a normal viewing distance they are not apparent. I am a pixel peeper (silver grain peeper?) though, so I'm working on ways to hide them, and though I haven't succeded yet, I am making progress. At 4x magnification, which would be approximately a 20x30 max print size, the abberations are only visible with a loupe.
 

Carnie Bob

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Joined
Nov 5, 2023
Messages
330
Location
Toronto , Ont Canada
Format
4x5 Format
There are abberations visible in these prints (8x magnification) but at a normal viewing distance they are not apparent. I am a pixel peeper (silver grain peeper?) though, so I'm working on ways to hide them, and though I haven't succeded yet, I am making progress. At 4x magnification, which would be approximately a 20x30 max print size, the abberations are only visible with a loupe.

That is pretty decent size not to see abberations if you have to see them with a loupe well no issue, also if one is using matt or semi matt paper I assume you can go bigger. I am quite encouraged with your progress, very well done.
 
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Nov 20, 2020
Messages
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Location
Western Massachusetts
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Here's an image of the current setup. I'm using a wall mount DeVere 5108 as the chassis, and the LCD slots in like a regular negative carrier. The two cables which come from the carrier are an HDMI which connects to the raspberry pi microcomputer which controls it, and a USB cable which powers it. I use a remote desktop program to control the raspberry pi and by extionsion the enlarger from outside the darkroom. In the future I'd like to build a custom chassis for it with an LED light source, as well as a way for indexing the enlarger height and automatically setting exposure time accordingly.
IMG_8359.jpg
 

AndrewBurns

Member
Joined
Jul 12, 2019
Messages
179
Location
Auckland, New Zealand
Format
35mm
Do you have the source code accessible on a Github repository by chance? I would be interested in this and it could be a nice community project to get a repository going with all the resources

Hey I just got around to adding a stripped-down and commented version of my python scripts to a github repo:


I've stripped out the functionality that nobody else needs (failed attempts to tile together multiple exposures). It still has functionality for applying a correction for uneven light sources and calibration curves for different print processes but if you want to use these functions you have to generate the inputs yourself for your specific hardware and process. If you don't want to use them you should be able to disable them.
 
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