SU33400A1 - The device for determining the time and exposure - Google Patents

Description

An instrument is proposed for determining the exposure time when photographs are enlarged. The essence of the invention lies in the fact that a lamochka is used in the device, the brightness of which equals the image of the negative on the screen with the brightness: the dimmer of the lamp bulb is graduated in seconds of exposure.

In FIG. 1 shows the instrument; FIG. 2 - cut it.

The device is a wooden box L whose wall is provided with a blade 10 and a scale 3 for the handle 2 of the rheostat, 4. Light bulb 9 (well, four volts), placed inside the crate / in front of the JO window, is powered by a transformer 7i connected to the device by means of a cord 5. Transformer 7 is installed in a transfer box 6, on the wall of which a plug 8 FOR plugs is connected to the transformer winding.

To determine the exposure when zoomed in, plug the transformer into the pin of the lighting network. Rotate the handle 2 of the rheostat 4 to regulate the heat of the light bulb 9, watching it by the brightness of the frosted glass inserted into the window JO. Color matte glass (yellowish-green) should match the shade of the rays, exit 85 )---: li:

condenser magnifying apparatus. |

Placing the device near the screen on which the image of the enlarged negative is projected, compare the luminance of this screen and frosted glass to achieve equalization by introducing and removing a rheostat 4 into the circuit of the light bulb 9. Having achieved this, notice the division of the scale 5 against which the handle 2 hand .

Scale 3 consists of three concentric rows of divisions, empirically graded in seconds of exposure time required for copying on normal, contrast, and gas printing papers.

The subject matter of the invention.

A device for determining the exposure time when copying with a design, characterized in that the electric bulb 9, covered with frosted glass in the JO window, is included in the lighting network by means of a transformer 7 and a rheostat 4, the handle 2 of which is equipped with a arrow to indicate on a scale of 5 exposure times, determined by comparing the illumination of the projection of the negative on the screen and ground glass.

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FIG. one

2