Friday, October 20, 2023
Hic sunt dracones.
Friday, October 13, 2023
Walkin' in color
Photo Opp organized another photowalk, this time at their home in central Appleton. I have been wanting to do some portraits that weren't just street shots. A gathering of photographers is a likely opportunity for willing sitters. The Variable Cuboid with the long-for-pinhole 60mm front seemed to be the best choice for that, as well as giving me the option to go to another angle of view if necessary. The autumnal date, relatively late in the partly cloudy day prompted me to use Lomography 800 to keep exposures as short as possible.
As we gathered, I expressed my hope to do some pinhole portraits. Brandi Grahl, who flashed me a brilliant smile in Kaukana, volunteered. Sitting on the front steps, she attempted to interpret my instruction to imagine she was being drawn by Hans Holbein, resulting in what I can only describe as a Mona Lisa smile.
The 60mm front for the Variable Cuboid has a .30mm pinhole, the 35mm front has a .25mm pinhole. Both of these have adjustable rising fronts with 20mm of travel. The 20mm front has a .20mm Gilder Electron Microscope Aperture. The Lomo 800 was the fifth roll developed in Arista.edu's quart kit.
Sunday, October 8, 2023
Pinholes as recommended by Lord Rayleigh.
The 4x5 Pinhole Lab Camera has four settings for the distance from pinhole to image plane, ergo angles of view. From stupidly wide 118° at 38mm to almost normal 55° at 120mm. The pinholes, one on the axis and 20mm above it in both dimensions, can be changed for the size with minimal diffraction Lord Rayleigh would recommend with his equations.
As a practical matter, the sizes appropriate to the different settings were the size I first succeeded in drilling three matching pinholes, in the range I was looking for. I've been using .28mm pinholes for the 60mm setting, which is a bit smaller than .32mm that the equations specify. (I also used them for the ultra-wide 38mm setting, because what's optimal when the distance to the pinhole ranges from 38mm at the center to 75mm at the edges?) For 90mm, I made a set at .36mm, again a little small and for the 120mm slot, .45mm holes, closer to the .46mm Lord Rayleigh suggests are the best for that distance than the other sets.
One day rummaging around for something else in my messy pinhole supplies, I encountered an envelope of .40mm Gilder Electron Microscope Apertures from a long ago deal with League of Upper Midwest Pinholers comrade Earl Johnson. I think he still does this for a buck apiece ($) with appropriate postage added. You can only get them from Gilder in quantities of 100.
When you ask Mr. Pinhole, the optimal size for 90mm from the pinhole is exactly .40mm.
It seemed appropriate to my course of studies in Antique Film Large Format Pinhole Photography to see if those mathematically perfect holes, a little smoother than I can drill myself, in a bit thinner metal, make any difference. My assignment is to expose a couple developer-tanks worth of my elderly sheets of Plus-X at moderately-wide 90mm with the repurposed consumable scientific supplies using photons instead of electron beams.
These all seem pretty darn sharp, especially the uncropped full-frame ones. (Not sayin' which ones those are.) Looking at them at full resolution I really can't tell if they're better than the smaller hand-drilled pinholes I have been using.
The 4x5 Plus-X was semistand developed in Rodinal 1:100.