DE364003C - Process for creating artistically smooth photographic images - Google Patents

Description

The creation of artistically soft photographic images presents a number of difficulties. and does not lead to entirely satisfactory results with currently used methods. The present invention aims to remedy the shortcomings of the known methods and achieves the purpose by that for the recording a chromatic plane-parallel plate in the beam path or

ίο is switched in front of the lens. The chromatic plane-parallel plate has known-

, lent the effect, rays of a certain Let wavelengths pass through uninterrupted, while they rays divergent

is wavelength towards the normal of incidence or breaks away from it. If the plate is calculated in such a way that it is suitable for the Absorption of significantly effective wavelengths does not result in any deflection, then through the inclusion of the plate in the beam path the position of the focus of the'photographic Image is not significantly affected, so setting the image in more usual Way can be done without the subsequent inclusion of the chromatic Plane-parallel plate in the beam path somehow. which adjustment is required.

The chromatic plane-spiral plate is permitted also the use of any lenses and does not have any special requirements at their correction to the purpose of the artistic blurring of the image to reach. It is therefore possible to obtain the highest quality images with the same lens To create sharpness and also by using the parallel plate images with artistic soft contours, the quality of the latter being particularly advantageous as a result Blurred images produced by other methods is excellent that the images in spite of their softness have a precise drawing, which is due to the fact that the individual pixels in all parts of the image have a sharp core of what .the cause will be specified later.

The effect of chromatic plan 'parallel plate on the pictorial character and a ι certain structural arrangement for their \ switched into the beam path are illustrated in the accompanying drawings.

Fig. Ι shows schematically the photographic light intensity of the various effective Wavelengths in function of an ordinary chromatically corrected lens their image location on the axis of the same.

Fig. 2 shows the light mountains under the precondition that a chromatic one is connected upstream Plane-parallel plate in front of the lens.

The figures show that in a conventionally chromatically corrected photographic lens, the photographic light intensity is essentially concentrated at one point on the axis. This is due to the fact that the objectives are calculated in such a way that the light rays for the D line and for the line G 'are combined in the same point on the axis.

If, on the other hand, a chromatic plane-parallel plate is placed in front of the objective in Fig. 1, which is calculated in such a way that it allows the rays corresponding to the wavelength G ' to pass through uninterrupted, then the result is an axial expansion of the intensity curve, although in contrast to With a chromatically uncorrected lens (monocle lens) the focus of the photographic light effect remains at the same point where the focus of the visually effective rays was previously when the image was set on the focusing screen. This center of gravity of the light effect, which for ordinary panels is approximately at the line G ' , results in a sharp core for each image point, around which the blurring is located, corresponding to the drop in light intensity on both sides of the setting plane, which can be seen in Fig. 2.

For the effect it makes no fundamental difference whether the chromatic plane-parallel plate is calculated in terms of a chromatic under- or over-correction. In general, however, it becomes more advantageous be to use a chromatically overcorrecting plate as the ones in question photographic lenses due to the nature of their secondary spectrum in the

Field of the 'actinic active rays' already themselves have \ correcting a low chromatic overpressure, which assists the action of the plate, so that these, in order to achieve the' same blur circle, in this case may be somewhat weaker: as an under-correcting, which I must counteract the secondary spectrum of the lens. For an attachment plate, which;

ίο for recordings with orthochromatic plate I. and yellow filter is calculated, due to j the reversed position of the secondary ' Spectrum in which now come into question-! the area of course the opposite conditions.

The curve shown in Fig. 2 corresponds to the effect of a chromatically over-correcting Facing plate.

When applying orthochromatic plates I would the intensity curve at prescreening ■ the chromatic plane-parallel plate even further to the long wavelength area toward extend j as it is shown in Fig. 2; it would j to that shown in Fig. 2 intensity 'curve, a further section on the line F corresponding point addition appear. In this case, when using the same chromatic plane-parallel plate, this part of the intensity curve or the images of the yellow-green rays _; lie outside the plane of the plate, while the part of the rays around the line G ' would be cut off by the yellow filter. It would appear incorrectly in this case \ the image because the Bildörter the effective radiation would be available to the panel plane. In order to avoid this, the chromatic plane-parallel plate which is used must be calculated differently in this case, namely in such a way that it transmits uninterrupted those rays which correspond to the center of gravity of the photographic light effect in orthochromatic plates and yellow filters, so that the sharp images of all effective rays again lie symmetrically on both sides of the plane of the plate.

The invention consists in a novel application of the so-called Schröder's chromatic plane-parallel plate. While the same so far only for this was used to check either the chromatic condition of lenses or a combination of a visually corrected one Lens (astro = or micro lens) the correction status of the visually corrected To influence objective so that the same in an objective of actinic achromatization has been transformed, in the present case it is a question of a cancellation of the chromatic correction in general, but with the / stipulation that the focus of the photographic effect on the same As with the photographic lens itself, the position remains without a combination with the chromatic plane-parallel plate.

In connection with this, there is also the type of use compared to the previously known a chromatic plane-parallel plate in connection with a visually corrected lens modified arrangement opposite the lens. While in the earlier type of use the chromatic plane-parallel plate on the picture side was arranged, in the present case practically only an arrangement on the lens side comes into question, as far as possible to achieve a strong and uniform effect over the entire image field.

The use of the above-described chromatic plane-parallel plate assumes that the plate enters the beam path as quickly as possible after each time the image is adjusted can be switched on. An arrangement of how this can be achieved is shown in Fig. 3 and 4 of the drawing.

Fig. 3 shows the end face of a lens mount and

Fig. 4 is a plan of Fig. 3 with a support device for a chromatic go Plane-parallel plate. To apply the plane-parallel plate ι are on the lens mount two hollow ring segments 3, 4 are provided. The chromatic plane-parallel plate can be placed on this after the image has been adjusted. set and just as easily removed again in order to carry out a new image adjustment.

Claims (3)

Patent Claims: ,1. Method of generating artistic soft photographic images, characterized in that a chromatic plane-parallel plate is provided for the recordings the chromatically corrected photographic lens is switched. 2. The method according to claim 1, characterized in that the chromatic Plane-parallel plate is calculated so that it is the position of the center of gravity of the photographic image essentially is unchanged. 3. Chromatic plane-parallel plate as an attachment plate for photographic lenses. 1 sheet of drawings.