DE326709C - Process for making color photographs - Google Patents

Description

The invention relates to a method of making color photographs on the multicolor grid plates holding the colors.

In the case of ordinary photography, careful efforts have been made so far, chromatic To correct dispersion, because one has to let the chemical focus coincide with the optical one to avoid any

ίο get blurry pictures. It has hitherto been assumed that the same also applies to Color photography applies and: for these same lenses as for ordinary ones Photography used.

It has already been proposed for taking pictures using the same additive color method to use glasses uncorrected for chromatic dispersion. The beneficial effect of the dispersion was however

not recognized in this way, rather you allegedly Eliminate or reduce harmful influence by antidotes such as color filters sought.

In contrast, according to the present invention, the chromatic dispersion of the objectives is not suppressed, but, on the contrary, its effect is enhanced. This takes place in that the recording is made by means of chromatically non-corrected and appropriately hyperchromatic objectives, the image being adjusted to the red rays. Thereby wirid achieved in the production of color images on a Auto chrome plate, that the colors are reproduced in a rather corresponding to the natural colors \ ^'r erhältnis by the chromatic dispersion wind used for obtaining Tongrenzen and increasing the color values. The lens is adjusted to red rays, while the other rays, which as a whole produce the complementary colors to red, are scattered over the various points of the plate, especially since their breakability is greater.

In the drawing, in Fig. 1, the routes ab, cd , etc. are bluish green stripes and the routes bc, de , etc. are red stripes.

When the device is set for the red rays, the rays emanating from bc ^{give a sharp image δ 1} - *: ¹ on the photographic plate or screen. The blue-green rays simultaneously give images at c ^ -d ¹ and V-dl · in front of the plate. They hit the plate in diffusion circles that are larger, the wider the aperture D is open. These diffusion circles originating from the chromatic dispersion affect the image of the red stripe, as is shown schematically in the drawing.

If it were ordinary photography, this encroachment would be the

Impair the sharpness of the outlines. But this does not apply to color photography to.

The blue-green rays which hit the part of the plate where the red image Z ^ -c ¹ is formed, namely, when mixed with these red rays, produce a certain amount of white light. As a result, the red image appears lighter in the image. The green

ίο On the other hand, images appear darker as a result of the Diffusion that has reduced its real light intensity. * ■

If the red stripe is so narrow, its image is completely covered by the diffusion circles is covered, then the red image will appear bright all over its surface. ' If, on the other hand, its width is so great that its average Part is not covered by the diffusion circles, as in Fig. 1, the described occurs

ao appearance only in the marginal parts.

■ The effect of the dispersion is in the fact that there is an opposition between the tones and an increase in their values, which is the case with the Color photography is very beneficial.

When the device is set for the blue-green rays, appear in the picture the green stripes lighter, while the red radiations darken.

What applies to the complementary colors also applies to the white light.

It should be assumed, for example, that there is a white stripe gh, FIG. 2, on a black or gray background in front of the lens. For example, if the device is set for the red rays, these rays will give a sharp image gMt ¹ on the screen.

The bluish-green rays give their image g ² - / i ^{2 in} front of it and hit the plate or the screen in circles of dispersion. This dispersion reduces the intensity of the blue-green rays themselves. The white seems to merge into orange-red, and the ground appears slightly colored by the diffuse blue-green.

In this case too, the contrast between the colors is increased without disturbing the outlines.

In the explanation above, only red and bluish-green have been mentioned. In In reality there are in white light all other rays of the spectrum except red. Her However, the mixture forms the complementary color to red. To simplify the description the radiations have therefore been divided into two groups, the first of which is the red Rays form, while the second wind formed by the remaining rays, whose Mixture forms the mentioned bluish green.

The above explanation shows that in all cases one does not oppose by using Dispersion of corrected lenses contains stronger contrasts of the tones and that as a result the sharpness of the outlines is increased, provided, of course, that the adjustment is made appropriately.

The experiment shows that the preceding theoretical explanations are in reality apply completely.

Any objective which has not been corrected for dispersion can be used for the practical implementation of the basic idea of the invention. Preferably, however, the lenses used are designed in such a way that the dispersive power of conventional glasses is increased ¹ . The degree of dispersion to be preferably used must reach and even exceed the degree of chromatic dispersion of the human eye.

It should be noted that these objectives are corrected for spherical aberrations, astigmatism, aplanatism of field ¹ and all other errors except for chromatic dispersion so that they give perfect images with monochromatic red light. Since the setting must now be made for red in order to achieve the best results, the corrections of these lenses must also be calculated according to the refractive index for red. ;

All glasses and glass combinations corresponding to this general definition can be used can be used practically.

For example, in FIG. Figure 3 of the drawing schematically shows an arrangement for color photography shown, which is sufficient for apparatus with a short focal length that cover only a plate of small dimensions should, for example a verascopic plate, or for apparatus for -kinematographic 1 °° Recordings.

It is useful to provide the lens L with a screen D , which is attached in front of or behind the lens as required. With the new objective, a ground glass screen V is used for adjustment, the matt side ν of which faces the objective as in ordinary photography and in contrast to that which is usual in color photography. no

The lens L can be biparabolic.

All known lens systems can be used if one uses the dispersion indices calculated in such a way that there is a large chromatic deviation. This is easy to achieve since substances are known that have very different dispersion indices with practically the same Have refractive index. The correction for the other deviations besides the dispersion will for the red rays and not

made as usual for the yellow rays

The devices according to the invention have two essential properties.
First of all, its light intensity is greater, which is easy to understand, since you can reduce the number of glasses and avoid the use of glasses that are cemented on top of each other, which absorb light, and especially because ίο you can enlarge the clear opening of the lens because it there is no longer any need to do it achromatic. The exposure time can be reduced as a result of the greater light intensity.

Claims (1)

Patent claim: Process for making color photographs on the color retention Multi-color grid plates, characterized in that the recording is made by means of 2c chromatically non-corrected and appropriately hyperchromatic lenses and the setting of the image red rays takes place. 1 sheet of drawings.