8"x10" Paper Negative Box Camera Images

[JoeV]

Here's a shot of the camera:




And a full description of the camera:
http://www.f295.org/Pinholeforum/for...8266965/s-all/

The heart of the camera is built around a nested box structure built from 1/4' black foamcore, then covered with adhesive countertop laminate to simulate a wood grain, which also adds some structural integrity. The nested box is then permanently bolted to a plywood base with tripod nut. The rear structure for the film holders is made from redwood scraps and aluminum "L" channel I had in my shop. The viewscreen is removable, about the same size as a film holder, and the screen material itself is an 8x10 plastic fresnel magnifier from Staples office supply, the front flat side being sanded with a random orbital sander to a buff finish.

*Joe

[JoeV]

Here's a view of the meniscus:



And a view of the meniscus lens from the inside of the box camera:


My new lens, a Fujinon Xerox:


A digital shot of the viewscreen (the digital camera upside down) focused on my workbench, with the Fujinon Xerox lens:


*Joe

[JoeV]

The rear of the camera where the view screen and/or film holders mount:


Looking into the slot where the film holder and/or view screen mount:


And another view of the slot:


~Joe

[Bill_1856]

Them's IMPRESSIVE!

[Jay DeFehr]

Fantastic! Thank you so much for posting, and reminding me how simple LF photography can be. I think your camera is worthy of film, but your paper negs look great!

[Jim Graves]

Absolutely outstanding ... 1 question ... what is "pre-flashed" paper?

Thanks for posting this!

[JoeV]

Absolutely outstanding ... 1 question ... what is "pre-flashed" paper?

Thanks for posting this!

Preflashing is something that I do to paper negatives, in the darkroom prior to loading into film holders, that improves their tonal range in high-contrast light (like scenic photography in the western US.) The common problem with using paper negatives as an in-camera film is excess contrast. Paper also doesn't have as wide of a tonal range as sheet film, in my experience. There are two types of paper available:

Multicontrast paper: It has a high contrast emulsion that's blue/UV sensitive, and a low contrast emulsion that's green sensitive. When used in daylight scenes, the blue/UV in the scene activates the high contrast emulsion, yielding an excessively high contrast negative. One solution other people have found is to use a yellow filter over the lens, helping to reduce the amount of high contrast producing light.

Graded paper: I use Freestyle's grade 2 glossy RC paper as a negative material (it dries flat, making it easier to contact print). It's contrast is rather insensitive to the color of light. Having a selection of paper contrast by grade is very convenient as an in-camera film; I wish we had this choice in sheet film.

In order to gain more shadow detail without having to over-expose the highlights, I give the paper a faint exposure in the darkroom prior to loading the paper into film holders. This faint exposure I've calibrated to yield a faint gray tone on an otherwise unexposed but developed sheet. How this works is obvious if you think about the Zone system: each higher zone is double the exposure of the previous. So if you preflash the paper to yield, say, a Zone II tone on the paper, that faint amount of tone is only 2^6=128 times less density than a Zone VIII highlight portion of the image. So the preflash exposure preferentially affects the shadows more than the highlights, helping to reduce excess contrast.

I originally tried using my enlarger as the light source, but even with the lens stopped down to F/32 the exposure times were too short (1-2 seconds) to reliably time with my darkroom timer. So I made a light source using a type S-11 bulb (120vac, standard base, round white frosted, 7.5 watts, available at hardware stores, looks like a golf ball in size) mounted into a soup can metal housing, stopped down to a 3mm aperture, suspended 30" above the table in my darkroom. Typical preflash times are 8-10 seconds, long enough to be accurately timed with my Gralab timer, and short enough to be convenient.

~Joe

[JoeV]

Franken-shutter:

I made a removable mechanical shutter that attaches to the front of the box camera using rubber bands. The purpose is to be able to use wider lens apertures in bright light, especially for portraits. The full story is on F295, here.

Here're a few images:

The general layout. The shutter is made from a frame of 3/4" square birch, sheathed in masonite. All are workshop scraps:


To mount the shutter on the camera, first the guillotine shutter is removed from the camera, then the shutter is mounted on the front and secured with elastic bands to the back. Here's the shutter being cocked:


Shutter cocked to 3/4 of slowest speed. There are eight speeds available, selected via a wooden dowel pin that engages one of eight holes in the rear blade disc:


Here's a shot of the shutter in mid-release. You can see the shutter blade is blurred by it fast motion:


~Joe

[jb7]

Impressive stuff, great pictures too-
I'm going to have to study your shutter in detail...
Do you reckon it could scale up, or might the inertia and springing get too great?

[argos33]

Joe,
Thanks for taking the time to explain everything. Nice job on the camera & shutter!