Large format negative from digital display

[salvatore]

I am interested in dichromated gum and carbon techniques, both needing large negatives.
In this thread I like to express my ideas and get some suggestions on a way to obtain them in case of a digital photograph, and avoiding the use of an ink jet printer, due to the ease with which they get clogged and rapidly useless unless continuosly used.
I like to build a device which will project the image on a lcd screen, say that of a computer or of a TV set of high definition (think of a 4K!) onto a black and white photographic film.
The size of the lcd could be from say 15 by 20 inches to 45 to 60 inches.
My basic question is: Which lens to use? Which is the optimum focal length? Any model in mind?

[ndg]

About 2 years ago, one of my colleagues saw some of my wet plates and wondered if I could do a portrait of his horse. Wet plate portrait of a horse? I laughed it off bit kept thinking. This what I did:
- I shot a digital image of the horse and saved it on a jump drive.
- I have a 42" LG 120 Hz TV in the studio that I screened the image on.
- I placed the TV with the image of the horse on it in front of my camera with my 16" Tessar lens and focussed the image on the GG.
- I prepared a 12" x 12" plate and captured this image:

(bad scan; scan it in 2 parts and tried to stitch it!)
It came out so well, they have it hanging in their home!

So I tried a second portrait but this time on 11x 14 photo paper using a Verito.
I developed the photo paper and contact-printed it on Ilford 300 paper.


I thought of writing it up but never can make the time. Beside I haven't used that method much anymore because I didn't really like the results.
The images have the signature of the first lens used and not so much of the second lens. The images also look like copies.
I prefer digital negatives muh more than this method.

So if you real want to, get an LCD or LED screen with as much brightness as possible. The size will depend on how big the negatives should be. You can go wrong with a 42".
Any lens will do. You can meter the brightness of the screen to give you an approximate ballpark for exposure.

[Tin Can]

About 2 years ago, one of my colleagues saw some of my wet plates and wondered if I could do a portrait of his horse. Wet plate portrait of a horse? I laughed it off bit kept thinking. This what I did:
- I shot a digital image of the horse and saved it on a jump drive.
- I have a 42" LG 120 Hz TV in the studio that I screened the image on.
- I placed the TV with the image of the horse on it in front of my camera with my 16" Tessar lens and focussed the image on the GG.
- I prepared a 12" x 12" plate and captured this image:

(bad scan; scan it in 2 parts and tried to stitch it!)
It came out so well, they have it hanging in their home!

So I tried a second portrait but this time on 11x 14 photo paper using a Verito.
I developed the photo paper and contact-printed it on Ilford 300 paper.


I thought of writing it up but never can make the time. Beside I haven't used that method much lately.

So get an LCD or LED screen with as much brightness as possible. The size will depend on how big the negatives should be. You can go wrong with a 42".
Any lens will do. You can meter the brightness of the screen to give you an approximate ballpark for exposure.

There goes the neighborhood.

Great idea!

[ndg]

I haven't used this method much anymore because I don't really like the results.
The images have the signature of the first lens used and not so much of the second lens. The images also look like copies.
I prefer digital and in-camera negatives much more than this method.

[nede]

Did it this week with my 8x10 camera on my imac27 screen
I pût some low contrast on the image and shoot it, measuring with my spotmeter.
Nice result but you can Count the pixel on the négative .... Not a very good idea in the end...

[ndg]

I got the best results when I used the 36 mp images form my Nikon d800E. With those, even the 11x14 images were satisfactory.
Lower res images tend to show pixelation. One could also match the size of the image to that of the screen to get optimal results, much like when printing digitally.

[salvatore]

When using the 36 mp image, which screen and which lens did you use?
Thanks.

[ndg]

When using the 36 mp image, which screen and which lens did you use?
Thanks.

The screen was an LG 42" LED 120Hz screen. If I remember right, one lens was 16" and the other 18" for 11x14. For 8x10, I tried a 14".

[salvatore]

The screen was an LG 42" LED 120Hz screen. If I remember right, one lens was 16" and the other 18" for 11x14. For 8x10, I tried a 14".

Thanks for the information.
The "lenses" were just enlarging glasses (one diopter) or a composite chromatic and distortion corrected objectives (of cameras, of enlarger, of projection)?
With some plywood I built a very rough optical bench composed of an image source (the screen of a Google Nexus 7 (about 12 by eighteen centimeters) a simple enlarging lens of about 10 cm focal length, diaphragmed by an 8 mm hole, then a plexiglas plate.
From the image source to the lens about 20 cm and same from lens to plexiglas.
I generated a test pattern and observed the projected image with a small enlarging glass made for the purpose of focus optimization by Kodak, by which I could observe, in the central portion of the image of about 3 by 3 centimeters a very sharp definition showing clearly the pixels.
Of course I would like to use some more efficient optical device than a simple lens, and for that I plan to try the following optics I have, remnants of my past activity in analogic photography:

Enlargement lens: Rodenstock Rodagon 50mm
Camera lens 1: Nikkor 35mm for Nikkormat camera
Camera lens 2: Nikkor 110mm for Nikkormat camera.

However, I would like to have the best for my application, and I would like some suggestion do build something which could give from a source ranging from 10 by 15 cm to 30 by 45 cm to an image of same size (possibly also a reduction or enlargement in the given range.
Which lens for this purpose? May be a large format camera lens of aroun 200-300 mm focal or an enlarging optics?
Lenses made for grqphic arts seem the best but prohibitive in price as new.

[ndg]

Thanks for the information.
The "lenses" were just enlarging glasses (one diopter) or a composite chromatic and distortion corrected objectives (of cameras, of enlarger, of projection)?
With some plywood I built a very rough optical bench composed of an image source (the screen of a Google Nexus 7 (about 12 by eighteen centimeters) a simple enlarging lens of about 10 cm focal length, diaphragmed by an 8 mm hole, then a plexiglas plate.
From the image source to the lens about 20 cm and same from lens to plexiglas.
I generated a test pattern and observed the projected image with a small enlarging glass made for the purpose of focus optimization by Kodak, by which I could observe, in the central portion of the image of about 3 by 3 centimeters a very sharp definition showing clearly the pixels.
Of course I would like to use some more efficient optical device than a simple lens, and for that I plan to try the following optics I have, remnants of my past activity in analogic photography:

Enlargement lens: Rodenstock Rodagon 50mm
Camera lens 1: Nikkor 35mm for Nikkormat camera
Camera lens 2: Nikkor 110mm for Nikkormat camera.

However, I would have the best for my application, and I would like some suggestion do build something which could give from a source ranging from 10 by 15 cm to 30 by 45 cm to an image of same size (possibly also a reduction or enlargement in the given range.
Which lens for this purpose? May be a large format camera lens of aroun 200-300 mm focal or an enlarging optics?
Lenses made for grqphic arts seem the best but prohibitive in price as new.

What about an Artar?