Microfilm camera attachment

Details Microfilm camera attachment Microfilm camera attachment

1978-06-28

1980-03-18

Gonzales, John

Photocopying

Contact printing

Light boxes

355 68, G03B 700

Patent

active

041936744

ABSTRACT:
A conventional portable microfilming camera having a generally fixed exposure is improved for use with slower films which are required for x-ray duplication. The improvement consists of placing a neutral density filter over the exposure controlling photocell thereby reducing the amount of light reaching the photocell. This in turn results in a longer period of time being required for the pre-set amount of light to reach the photocell thereby causing a longer exposure time as required by the slower film. A light table is provided for back-lighting the x-rays and selectively sized masks are hingedly affixed to the light table for selective masking of the unused portion of the light table. A beam restrictor is used in conjunction with the neutral density filter to ensure that the photocell does not view the uncovered portion of the light table.

REFERENCES:
patent: 2024661 (1935-12-01), Riszdorfer
patent: 2124286 (1938-07-01), Burckhardt
patent: 3649120 (1972-03-01), Pfeifer et al.
patent: 3795445 (1974-03-01), Hamlin et al.
patent: 4000497 (1976-12-01), Galbraith, Jr.
patent: 4066346 (1978-01-01), Toyama et al.

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