DK150470B - PROCEDURE FOR SETTING UP A REPRODUCTION CAMERA - Google Patents

Description

15 Ο Λ 7 O

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The invention relates to a method for setting a reproduction camera comprising an image plane, an objective plane and an original plane, by means of a calculator.

5 Of course, in a reproduction camera, you are interested in setting the lens plane and the original plane so that the image becomes sharp. Providing the image in question on a matted side of a glass plate and observing the sharpness from the other side of the plate will inevitably cause parallax errors. One can also provide the image on the other side of the glass plate. However, the vitreous generates imaging during exposure (for example, due to refraction or blistering of the glass).

The method according to the invention is characterized in that the lens plane and the original plane are first adjusted to provide on a glass plate inserted in the beam passage a sample image on the side of the glass plate that faces away from the beam path, after which the calculator calculates how the settings of the planes 20 have to be corrected. net when the glass plate is taken out, the correction being calculated by dividing the propagation path in the glass plate by the refractive index of the glass, after which all the planes are possibly displaced corresponding to the calculated correction and a light-sensitive material is finally placed in the displaced image plane.

This facilitates the setting which is automatically corrected when the glass plate is removed. The correction is made by dividing the path of propagation in the glass plate by the refractive index of the glass.

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The invention will be explained in more detail below with reference to the drawing, in which% fig. 1 shows the original plane, the lens plane and the image plane 35 of a reproduction camera; and FIG. 2 the reproduction camera itself.

2 '150470

When using a reproduction camera consisting of an original plane 3, a lens plane 4 and an image plane, you are obviously interested in adjusting this.

According to the invention, a glass plate 1 is inserted in the beam passage, the imaging taking place on the frosted back of the glass plate. It will thereby be possible to make the sharpness adjustment, for example by means of a loupe 2, which can be placed very close to the image outside the beam passage.

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However, during normal reproduction, one is not interested in having the glass plate 1 lying in the beam passage. A calculator built into the camera therefore calculates how to correct the position of the original plane 3 and the lens plane 4 when removing the glass plate 1. The correction can e.g. is made by means of the arrangement referred to in German Publication No. 29 50 933.

A glass thickness of 6 mm corresponds to an air thickness of approx.

20 by 4 mm, multiplying by the refractive index of the glass, corresponding to the optical path length being unchanged.

The calculation is made according to the lens formula, which must be satisfied, 25 1 1 _ 1 a b f, the distances in question being optical path lengths.

When the glass plate 1 is removed, the sheet of photosensitive material may be carried by a suction cassette 5.

FIG. 2 shows an example of the entire reproduction camera, with a suction cassette embedded in the lid 5.

35 According to the invention, it has thus been disclosed how one would be able to adjust with the glass plate inlaid without, for that reason, being a nuisance during exposure.