CH348045A

CH348045A - Device for focusing a camera

Info

Publication number: CH348045A
Authority: CH
Inventors: Andre Dodin Lucien Jules Emile
Original assignee: Zeiss Ikon Ag
Priority date: 1957-02-12
Filing date: 1958-02-12
Publication date: 1960-07-31

Description

Dispositif pour la mise au point d'un appareil photographique Il est connu que deux prismes de refraction, juxtaposes en opposition pres du plan de mise au point d'un objectif convergent, permettent de d6ter- miner 1'emplacement exact de ce plan par observation de la coincidence de deux lignes appartenant ä 1'image formee par cet objectif. Device for focusing a photographic camera It is known that two refracting prisms, juxtaposed in opposition near the focusing plane of a convergent objective, make it possible to determine the exact location of this plane by observation. of the coincidence of two lines belonging to the image formed by this lens.

11 est possible de remplacer ces deux prismes par un seul. Une des faces du prisme Sera disposde de faQon ä renvoyer sur Neil de Fobservateur les rayons issus dune region de Fobjectif situe sur son plan prin- cipal mais en dehors de Faxe, une autre face Sera disposee de fagon exactement symetrique par rapport ä Faxe de fagon ä jouer exactement 1e meme röle pour une autre region de 1'objectif, symetrique elle aussi de la premiere. It is possible to replace these two prisms with a single one. One of the faces of the prism will be placed in such a way as to reflect on Neil of the observer the rays coming from a region of the objective located on its principal plane but outside of the face, another face will be placed in an exactly symmetrical way with respect to the face to play exactly the same role for another region of the lens, also symmetrical to the first.

Une lentille dite de champ pourra etre adjointe au prisme pour que soit formde nette sur 1'oeil 1'image d'un point place au centre des regions excentriques de 1'objectif indique ci-dessus. A so-called field lens may be added to the prism so that the image of a point placed in the center of the eccentric regions of the objective indicated above is formed on the eye.

Dans 1e dessin annexe, plusieurs formes d'ex6cu- tion du dispositif selon 1'invention sont representdes schematiquement ä titre d'exemple. In the appended drawing, several embodiments of the device according to the invention are represented schematically by way of example.

A) Le prisme pourra etre utilise Beul sans adjonc- tion d'aucun accessoire, sauf ceux destines ä 1e sup- porter, il pourra eire constitue par une baguette de verre de forme convenable traversant entierement 1e champ de 1'image et coupant perpendiculairement Faxe optique ; c'est la disposition indiqude en fig. 1. Dans ce cas, il sera soutenu mecaniquement par ses deux extremites. A) The prism can be used without adding any accessory, except those intended to support it. optical; this is the arrangement shown in fig. 1. In this case, it will be mechanically supported at both ends.

0n a represente en 1 les limites du champ ; en 2 la baguette prismatique en elevation ; en 3 la pro- jection oblique de la baguette prismatique. 0n has represented in 1 the limits of the field; in 2 the prismatic rod in elevation; in 3 the oblique projection of the prismatic rod.

B) Le prisme pourra etre soutenu par collage optique sur une surface de verre, soit (ans tonte la largeur du champ, soit simplement, pour un fragment, colle au centre. La surface de verre sur laquelle 1e prisme est colle peut faire partie (Tune plaque de verre plan parallele ou d'une lentille ; c'est la seconde disposition qui est indiquee en fig. 2. B) The prism can be supported by optical bonding on a glass surface, either (without mowing the width of the field, or simply, for a fragment, glued in the center. The glass surface on which the prism is glued can be part ( A parallel plane glass plate or a lens; it is the second arrangement which is indicated in Fig. 2.

4 est la vue en elevation de la lentille avec 1e fragment de prisme colle au milieu ; 5 est la coupe de la lentille en projection oblique. 4 is the elevational view of the lens with the prism fragment stuck in the middle; 5 is the section of the lens in oblique projection.

C) Les surfaces planes du prisme pourront etre tailldes au diamant (ans 1e corps d'un verre plan ou d'une lentille suivant les dispositions generales de la fig. 3 et de la fig. 5 (partie 1 de la figure). C) The plane surfaces of the prism can be diamond-cut (in the first body of a plane glass or a lens according to the general provisions of fig. 3 and fig. 5 (part 1 of the figure).

D) La lentille ou 1e verre plan pourront etre sec- RTI ID="0001.0271"WI="11" HE="4" LX="1108" LY="1756"> tionnes obliquement, les deux moities pouvant eire reunies ensuite au prisme par collage de fa@on ä constituer un element unique. Dans cette forme de construction, an pourra utiliser un prisme traversant completement 1e champ comme (ans la fig. 3, soit, comme (ans la fig. 4, etre reduit ä un fragment cen- tral. Dans ce dernier cas les cavites restantes seront obturees par des morceaux de verre de forme eonve- nable. Les variantes C et D presentent 1'avantage sur les premieres de n'offrir aucune saillie au-dessus de la surface plane du support, ceci facilite les disposi- tions accessoires suivantes. D) The lens or the flat glass may be sectioned obliquely, the two halves then being able to be reunited at the prism by gluing so as to constitute a unique element. In this form of construction, a prism can be used which completely crosses the field as (in fig. 3, or, as (in fig. 4), be reduced to a central fragment. In the latter case the remaining cavities will be closed by pieces of glass of suitable shape Variants C and D have the advantage over the former of not offering any projection above the flat surface of the support, this facilitating the subsequent accessory arrangements.

E) 0n peut tailler separement un verre depoli en y menageant une zone centrale transparente et appuyer la surface travaillde de ce verre sur Farete du prisme. Dans cette disposition, la mise au point indiquee par 1e verre depoli sera identiquement la meme que celle indiquee par 1e prisme. E) A frosted glass can be cut separately by creating a transparent central zone and resting the worked surface of this glass on the edge of the prism. In this arrangement, the focus indicated by the ground glass will be identically the same as that indicated by the prism.

La fig. 5 montre en 1 la position du verre par rapport ä la lentille (ans 1e cas des variantes A et B, et en 2 la position Jans les variantes C et D ; Fencombrement est moindre (ans 1e second cas. 3 est la projection verticale des deux dispositions repr6sent6es ä la fig. 5. fig. 5 shows at 1 the position of the lens relative to the lens (in the first case of variants A and B, and at 2 the position in variants C and D; the size is less (in the second case). 3 is the vertical projection of the two arrangements shown in Fig. 5.

Les variantes C et D permettent aussi de d6polir directement 1a surface plane voisine du verre support, ou de la lentille, avec ou sans zone polie. Variants C and D also make it possible to directly etch the flat surface adjacent to the support glass, or to the lens, with or without a polished zone.

F) Le prisme d6crit peut occuper la totalitd du champ, soit qWil soit tail16 avec une surface post6- rieure plane, soit que cette surface postdrieure est tai116e en forme sph6rique pour former lentille de champ. F) The prism described can occupy the entire field, either if it is cut with a flat rear surface, or if this rear surface is cut in a spherical shape to form a field lens.

La fig. 6 indique un mode de construction de la variante F formant lentille. 0n peut y adjoindre un verre d6poli avec ou sans reserve polie. Comme dans la disposition de la fig. 5 (Partie 1 de la figure). Dans toutes les variantes indiqudes ci-dessus, la ligne de s6paration des deux surfaces inclinees du prisme est disposee obliquement par rapport ä la figure du champ suppose rectangulaire. La solution de conti- nuite qui apparait dans les lignes utilisdes pour la mise au point est en effet maximum quand ces lignes font un angle de 45o avec 1'arete du prisme. Comme les lignes verticales et horizontales sont plus commu- nes Jans la nature que les lignes obliques, la dis- position oblique du prisme est plus avantageuse, mais elle n'a rien d'absolu. fig. 6 indicates a mode of construction of the variant F forming a lens. You can add a frosted glass with or without a polished reserve. As in the arrangement of fig. 5 (Part 1 of the figure). In all the variants indicated above, the line of separation of the two inclined surfaces of the prism is arranged obliquely with respect to the figure of the supposedly rectangular field. The solution of continuity which appears in the lines used for the focusing is indeed maximum when these lines make an angle of 45° with the edge of the prism. As vertical and horizontal lines are more common in nature than oblique lines, the oblique arrangement of the prism is more advantageous, but it is not absolute.

G) Il West pas indispensable, pour assurer un bon fonctionnement, que l'616ment prismatique reste rectiligne, il peut prendre une forme de ligne brisee et meine de ligne courbe. Dans ce cas, au point de vue strictement gdom6trique, il ne s'agit plus d'un prisme mais d'un volume limit6 par deux trones de cöne. Des formes de ce genre sont tres difficiles ä fabriquer en verre par les procedes habituels de 1'op- tique, mais il reste possible de les tailler directement dans 1e verre ä 1'aide d'outils en diamant. Dans cer- tains cas, il est meine plus facile de faire cette taille en forme de circonf6rence, par exemple, qu'en forme de droite. G) It is not essential, to ensure proper operation, that the prismatic element remains straight, it can take the form of a broken line and even a curved line. In this case, from the strictly geometrical point of view, it is no longer a matter of a prism but of a volume limited by two cone rings. Shapes of this kind are very difficult to manufacture in glass by the usual optical methods, but it is still possible to cut them directly in the glass using diamond tools. In some cases, it is even easier to make this size in the shape of a circumference, for example, than in the shape of a straight line.

La fig. 7 montre un exemple de taille de ce genre en forme de circonf6rence au milieu dune lentille. En 6, an voit la coupe et 1'61evation du prisme bi- conique ; en 7, an voit la lentille dans laquelle il est taill6. Cette disposition est aussi realisable, par mou- lage ou taille, en matieres plastiques, sur lentille ou Plaque plane. fig. 7 shows an example of such a size in the shape of a circumference in the middle of a lens. In 6, an sees the cut and elevation of the biconical prism; in 7, an sees the lens in which it is cut6. This arrangement can also be made, by molding or cutting, in plastic materials, on a lens or a flat plate.

Il est, bien entendu, possible d'assurer des assem- blages de fragments de prismes avec des verres ou des lentilles de toutes sortes, ordinaires ou de Fresnel, suivant des procdd6s qui utilisent actuelle- ment RTI ID="0002.0279" WI="5" HE="4" LX="387" LY="2294"> les doubles prismes juxtapos6s en opposition. It is, of course, possible to ensure assemblies of fragments of prisms with glasses or lenses of all kinds, ordinary or Fresnel, according to processes which currently use RTI ID="0002.0279" WI=" 5" HE="4" LX="387" LY="2294"> double prisms juxtaposed in opposition.

La construction de ces assemblages est facilit6e par le fait qu'il ne s'agit plus de r6unir deux prismes au support, mais un seul. The construction of these assemblies is facilitated by the fact that it is no longer a matter of joining two prisms to the support, but only one.

Ort peut, par exemple, tailler 1e prisme unique en forme de cylindre et 1'incruster dans un trou tra- versant entierement une Plaque de verre et, si cela est utile, en collant une lentille sur 1e prisme ou meine en taillant une surface lenticulaire dans la face post6rieure du prisme au dos de celui-ci. Dans une surface de verre appartenant ä une Plaque ou une lentille, an peut pratiquer une cavit6 sph6rique concave dans laquelle an peut coller un fragment de prisme, ä la surface post6rieure duquel an a donn6 la forme convexe voulue. Ort peut ope- rer de meine, mais en donnant ä la cavit6 et au prisme des formes cylindriques complementaires. Ort can, for example, carve the single prism into a cylinder shape and embed it in a hole going all the way through a Glass Plate and, if useful, glue a lens to the prism or even carve a lenticular surface. in the posterior face of the prism on the back of the latter. In a glass surface belonging to a Plate or a lens, an can make a concave spherical cavity in which an can stick a fragment of prism, to the rear surface of which an has given the desired convex shape. Ort can operate at the same time, but by giving the cavity and the prism complementary cylindrical shapes.

En utilisant des matieres plastiques, il est encore plus facile d'assurer toutes les combinaisons possibles. By using plastic materials, it is even easier to ensure all possible combinations.

Claims

CLAIM Device for focusing a camera, comprising means capable of causing a shift to appear between at least two parts of the image given by the lens, when the exact focusing position is not reached, characterized in that said means comprise an optical element having two faces connecting along an edge entirely contained in a plane, device arranged so that, when the position of exact focus is reached, said edge is in the first plane fixed where the image should be formed. SUB-CLAIMS 1. Device according to claim, characterized in that said element 616 is a prism, the edge of which is arranged obliquely with respect to the lateral limits of the image in normal position.

2. Device according to sub-claim 1, characterized in that the prism only extends over parts of the image plane.

3. Device according to sub-claim 2, characterized in that the prism extends over the central part of the image plane.

4. Device according to sub-claim 1, characterized in that the prism extends across the entire surface of the image plane.

5. Device according to sub-claim 1, characterized in that, when using a single prism, the two inclined faces of the latter each extend over half of the total surface of the plane of the prism. picture.

6. Device according to sub-claim 1, characterized in that it comprises several prisms.

7. Device according to sub-claim 6, characterized in that RTI ID="0002.0548" WI="4" HE="4" LX="1477" LY="2346"> the faces of the prisms are inclined from same angle. B.

Device according to sub-claim 1, characterized in that the faces of the prisms are inclined at different angles.

9. Device according to claim, charactdris6 in that said edge is circular.

10. Device according to sub-claim 9, characterized in that said element is concentric with the optical axis.

11. Device according to claim, characterized by a field lens forming support for said element.

12. Device according to sub-claim 11, characterized in that said faces are imprinted in the field lens.

13. Device according to sub-claim 11, characterized in that the faces of said element are cut in the field lens.

14. Device according to sub-claim 11, characterized in that said element forms a unit with the field lens.

15. Device according to sub-claim 11, comprising a Fresnel lens, characterized in that the Fresnel lens is arranged in such a way with respect to the field lens combined with said element in such a way that the edge of said element is found near the edges of the Fresnel lens.

16. Device according to claim, charac- ris6 in that it has a surface forming a support for said element, said surface being partly frosted and partly transparent.