The camerawhat is the Eidograph?
The Eidograph is a camera that exists as a specification and behaves like an instrument: every ability measured, every refusal written down beside it. It is named for Wallace's eidograph of 1821, a precision enlarging instrument, because that is literally what it became.
Mk1, the bench camera
A four-by-five sheet that exists only as a program. The focal length falls out of a declared field of view, the aperture is a real entrance pupil, and in front of the sheet stands real glass: more than a thousand objectives, 1840 to 2007, each traced from the radii and thicknesses its own patent records. Their faults are not dialled in; they are what the tracing produces. Behind the sheet is a darkroom of historic processes - platinotype, tricolour carbro, solarisation - each derived from what the chemistry does rather than what it looks like.
Mk2, the enlarger
The same camera made scalable. The negative becomes a store no memory needs to hold whole; the exposure spreads across unequal GPUs and later across strangers' machines; a deep-zoom pyramid turns a hundred-gigapixel negative into a browser tab. Nothing in the image path changed - Mk2 is gated bit-for-bit against Mk1 - which is the point: scale was added to the instrument without touching what the instrument says.
The character clause
What makes it a camera rather than a renderer is what it refuses. It will not add a glow because glow looks right. It will not fake a lens it cannot trace, and where a design refuses to trace honestly it says so instead of substituting the nearest survivor. Every number on these pages is measured or it is labelled a projection with its anchors shown. An instrument that cannot be wrong cannot be right either; this one keeps itself falsifiable on purpose.
Sources
The name is William Wallace's. He built the eidograph in 1821 and presented it to the Royal Society of Edinburgh in November of that year; the paper describing it, and the pantograph it was built to improve on, was read in 1831 and printed in the society's Transactions in 1836. The date above is the instrument's, and 1836 is the citation's.
The glass stands on published optics rather than on taste. The aberration sums the shader carries are Welford's, from Aberrations of Optical Systems of 1986, checked term by term against chapter 29 of Gross and others' Handbook of Optical Systems, volume three, whose own citation for the set is Welford. What lets an objective from 1840 be traced at all is the dispersion work: Sellmeier's resonance form of 1871, Conrady's three-constant reconstruction, and Schott's technical information TIE-29 for the reference wavelengths and for the tolerance a real melt varies by. The darkroom's response curve, the toe and the shoulder both, is Hurter and Driffield's of 1890, and the modern statement of it is Mees and James.
Those are the papers, not a warrant. Each was fetched and read against the claim it is offered for, quotation and locator recorded, and where the reading needed correcting the correction is written down beside it - in the evidence dossiers kept with the instrument's own documentation rather than on this page.