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UREMBO NA USTAWI
UJANJA
UTAMADUNI NA HISTORIA
BURUDANI
MAZINGIRA
CHAKULA NA VINYWAJI
UHANDISI WA KINYUME
SAYANSI
MICHEZO
TEKNOLOJIA
VAZI
Photoelectric Exposure Meter
Photographers judged exposure by eye, by printed tables, or with extinction meters that asked them to read the dimmest visible number. Edward Weston (the instrument maker, not the photographer) used a photovoltaic cell that generates its own current in light and fed it straight into a sensitive meter marked in exposure terms. No battery, no judgement.
**US 2,016,469**, "Exposure meter", Weston, assigned to Weston Electrical Instrument, filed 31. December 1931, granted 8. October 1935: an instrument "for the direct determination of the correct exposure conditions", improving on earlier current-generating cell meters whose output was too small and whose construction was impractical.
**You build the same thing** from a small solar cell and a multimeter, calibrate it against a lux meter, and turn its readings into shutter speeds.
Mwanzo
90 minutes
Maagizo
1
1
Cell and meter
Cell and meter
Clip the solar cell's two leads to the multimeter set to DC milliamps (or microamps). This short-circuits the cell through the meter - the current is what you read.
Vifaa kwa hatua hii:
Solar Cell Mini - 350mV1 kipandeZana zinazohitajika:
Kipima-umeme cha aina nyingi
Alligator to Alligator Cables2
2
A hood
A hood
Glue a black card tube 30 mm long around the cell so it sees only light from in front, as Weston's meter did.
Vifaa kwa hatua hii:
Kadi nzito nyeusi1 karatasiZana zinazohitajika:
Kisu cha kazi za mikono
Bastola ya gundi ya moto3
3
Calibrate
Calibrate
Hold the cell and the lux meter side by side, facing the same way, in four very different lights: a dim room, a lamp, a window, open shade outdoors. Note both readings each time.
Zana zinazohitajika:
Kipima mwanga4
4
Current to exposure
Current to exposure
Inapakia daftari la Jupyter…
5
5
Use it
Use it
Stand at the subject, point the hood back towards the camera, read the current, and set the camera manually from the notebook's table. Compare with the camera's own meter.
Zana zinazohitajika:
Kipima-umeme cha aina nyingi6
6
History & Context
History & Context
**What the patent specifies:** a light-sensitive current-generating cell connected to a measuring instrument reading directly in exposure terms. **Modern build (derived):** a silicon solar cell and a multimeter.
Weston's selenium-cell meters, sold from 1932, made metering routine; cameras later built the cell in. Its limits: selenium cells lose sensitivity in dim light and age, and any meter averages the scene - a snowfield or a black cat still fools it.
Vifaa
2- Solar Cell Mini - 350mVKamisheni 10%1 kipande$2.22
- 1 karatasiKishikilia Nafasi
Zana Zinazohitajika
5- Kishikilia Nafasi
- Alligator to Alligator CablesKamisheni 10%$3.58
- Kishikilia Nafasi
- Kishikilia Nafasi
- Kishikilia Nafasi
Jumla inayokadiriwa
Kile mtengenezaji alinunua. Malighafi zisizo na bei hupatikana pale unaponunua.
Blueprint zinazohusiana
Blueprint hizi zinashiriki maarifa — mbinu, vifaa au kanuni
CC0 Umma Wote
Mchoro huu umetolewa chini ya CC0. Uko huru kunakili, kubadilisha, kusambaza, na kutumia kazi hii kwa madhumuni yoyote, bila kuomba ruhusa.
Saidia Mtengenezaji kwa kununua bidhaa kupitia Mchoro wao ambapo wanapata Kamisheni ya Mtengenezaji iliyowekwa na Wachuuzi, au unda marudio mapya ya Mchoro huu na uiunganishe kama kiungo katika Mchoro wako kuchangia mapato.