A medium-format film camera on a tripod in a granite valley at golden hour

Glass Works Lab

The 503CX, metered.

This one needs a bigger screen: a medium-format camera, modelled part by part, standing in a valley you can meter. Open it on a laptop or desktop.

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Glass Works Lab · Yosemite Valley

The 503CX, metered.

A 1988 medium-format camera that never had a light meter, standing at Yosemite's classic viewpoints. Open GlassMeter to meter it the way the app does.

18:36

Portra 400

Drag to aim · click to spot-meter · double-click to focus

DoF — — EV —

About this page

A meterless camera, a real valley.

The 503CX (1988) has no light meter. Photographers carried a handheld one, and GlassMeter puts that meter, plus its Zone System tools and film simulation, in your pocket. Here the camera stands at real Yosemite viewpoints so you can use both together.

What's real

The valley. Elevation from USGS 3DEP (1 m lidar around each viewpoint), colour and land cover from USDA NAIP aerial imagery, and the Merced from USGS hydrography. The sun and moon follow their true paths for any date you choose, the stars and Milky Way turn overhead at night, and the sky is a physically based atmosphere.
The light. Scene brightness is calibrated so a grey card in noon sun meters EV 15. The meter reads what the lens sees and averages in log space, just like the app.
The film. The curves, grain, halation and filter responses are the app's own code, ported line for line.
The optics. The field of view, depth of field (CoC 0.05 mm) and aperture scale come from each Zeiss CF lens's data. The ground glass shows the lens wide open and mirror-reversed. Long lenses lose the top of the screen to the 503CX's non-gliding mirror.

How to shoot

Open GlassMeter with the app icon. Drag in the viewfinder to aim.
Click the brightest and darkest tones you care about to pin spot readings. Each pin shows its zone.
Press METER; the unlocked dial solves. Lock a dial (red button) to hold it.
Focus by double-clicking the viewfinder, or grab the lens's focusing ring in 3D.
Release the shutter. The mirror rises, the leaf shutter fires, and a print develops.

Credits

Elevation: USGS 3DEP. Imagery: USDA NAIP. Hydrography: USGS NHD. Names: USGS GNIS (all public domain). Stars: Yale Bright Star Catalogue. Milky Way: NASA/Goddard Space Flight Center Scientific Visualization Studio, Deep Star Maps 2020; Gaia DR2: ESA/Gaia/DPAC (CC BY-SA 3.0 IGO). El Capitan's face: USGS ground-based lidar and imagery, May 4 2022 (Corbett, Collins & Helfrich; CC0). Half Dome and Bridalveil: USGS 3DEP 2019 airborne lidar; Half Dome's colour from the photographer's own photographs. The Moon: NASA's Scientific Visualization Studio CGI Moon Kit (LRO LROC colour mosaic, public domain), placed by the IAU rotation model. Ground and bark textures: Poly Haven (CC0). The camera is modelled from the 503CX manual's dimension drawing and the Zeiss CF datasheets; it carries a Glass Works nameplate and is not affiliated with Hasselblad or Zeiss. Built with three.js.

Grinding the glass…