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[Concept]
The amplification is a negative image through the lens of the enlarger expanded to form a clear image in the enlarged paper.
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[Structure]
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. Lighting system (light room)
In the upper part of the magnifier, by the light source, reflector, condenser lens or frosted glass for lighting negatives used creamy white bulbs, frosted bulb or efficient tungsten halogen lamp light source.
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2 [film clip]
Frames of wood or metal, the backsheet on the frame; also some put in the box between a Layer a transparent glass, the backsheet is sandwiched in the middle.
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3 [dark box]
Usually using the scalable Piqiang or metal cylinder, which is connected to the lens and the condenser lens, can be free to stretch, and easy to enlarge light.
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4 zoom lens]
Zoom lens is the most important part of the enlarger, its requirements and the camera lens, aberration than being good, to get a clear image, but the camera lens is the distance the subject image clearly manifested, and the amplification lens is close negative images clearly enlarged.
The length of the length of the focal length of the zoom lens should and negatives of size with the zoom lens focal length should be roughly the same length of the diagonal and negatives that large negatives size, use telephoto zoom lens, the negatives hours should switch to short-focus zoom lens .
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[Pressed cardboard]
Pressed cardboard is used to pressure to enlarge the paper, and with activity photo frame to adjust the phase and amplitude size.
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6 [bracket]
It is supported by the larger machine body, and can move up and down to adjust the ratio of object and image will tune body fixed at the desired height.
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7 [pedestal]
Placement pressed cardboard, equipped with a mounting bracket with the column base.
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Classification
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1 [concentrating]
Between the light source and the film the condenser group condenser, light loss is less high brightness, a clear picture of the photo release, but the temperature is high, the negatives from the condenser group (condenser) close, the film in the film holder little longer easy damaged, the contrast is strong, and the particles on the backsheet, scar easily exposed.
This structure is the basic structure of the projection equipment (film machine, slide projector, drawing projector, print enlargers, etc.).
This amplification imaging system, the image plane (zoom paper or screen) of the light intensity decreases with the lens magnification. Therefore, use of lighting systems to provide more light energy to make a larger paper to obtain sufficient illuminance of the image.
Enlarger consists of two main parts:
① by the objective lens, the backsheet, the zoom consisting of imaging section of the paper;
(2) by a bright light source, condenser group constituted the condenser part (lighting system).
The role of the condenser has two aspects.
Enlarging paper can the one hand, the backsheet is not added before, to obtain a strong and uniform illumination, the light source itself does not appear structure (such as a filament, etc.) like; zoom paper can form a clear image when the join backsheet.
The one hand, can enhance zoom paper illuminance. Converging portion of the light energy capacity with the light source itself luminous intensity, the size of the light source, the angular aperture of the condenser lens group and other factors. When the emission intensity is constant, the larger the source area, the larger the aperture of the condenser lens, the light provided by the condenser more energy. Whether the light energy are provided by the illumination system can all enter the imaging system depends on the imaging relationship of the two.
Therefore, it must be appropriate to arrange the mutual position of the objective lens, a condenser and the object.
In order to make the light emitted from the light source can all reach the image plane of the beam through the condenser, often using the methods to achieve so-called into intermediate image.
The beam of light through the condenser lens group into an intermediate image, the In the backsheet smaller, so that the intermediate image near the backsheet; backsheet larger seasonal zoom lens near the intermediate image is located.
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2 [astigmatism]
No condenser lens between the light source and the backsheet of this amplifier, therefore, light use efficiency and clarity is not as high gathers light type amplifier.
Opal lamp light source, installed between the film and the light source from scattering effect of the opal glass (or frosted glass), so the illumination light of the backsheet softer adapted portrait photograph enlarged, usually frosted glass is fixed, no adjustment it is easy to use.
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3. [Half concentrating]
This amplification of the light source in front of the machine is not only equipped with a converging condenser, also fitted from the scattering effect of the opal glass or frosted glass, so its performance characteristics between the between the concentrating and the astigmatism of formula; light loss medium, the contrast between the moderate and softer light.
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4 [reflection]
Add a plane mirror, the mirror between the light source and a condenser lens group plating luminescent film, the absorption of infrared radiation, may improve the condition of the backsheet is heated.
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[Basic Operation]
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1. [Install negatives]
Wipe clean negatives into the holder, negatives edge with black paper box blocked, and then loaded into the enlarger, film face down, facing the camera.
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2 [regulating body]
First need to enlarge the frame of mind of the platen to the scale on the the box shop into a blank sheet of paper;
Open enlarger light source, the film image cast on white paper, lifting larger machine body, you can see the white paper image size change.
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3 [tune coke]
On white paper through Step 2 can be obtained a suitable size image, but not necessarily clear, the distance between the lens and the backsheet must be adjusted in a small range, until a clear image for projection in the enlarged platen, which is the focusing process.
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4. Adjust aperture]
In order to facilitate the observation of the focusing degree, usually is in focus when the try to open the large lens aperture, the focusing is completed, the aperture must be retracted into the required number of stages.
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5 [exposure]
Select the length of exposure time, we must consider the following five factors:
① light source intensity;
(2) the negatives the density;
③ the size of the zoom magnification;
④ zoom speed of the photosensitive paper;
⑤ the aperture size and the like.
Usually used experimental approach to determine the correct exposure time, the free segments of the exposure method, the partial occlusion can also be used in an experiment to enlarge paper segment for different time of exposure after development in accordance with the different exposure effect of the test paper to select Determine the best exposure time.
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【Article is excerpted from: Baidu Encyclopedia】
【Network reprint / Just reference】
【Translation is by Goolge】
