Light-projecting device

1. A light-projecting device for a view finder, comprising:

an ocular optical system that faces an emergent opening of a hollow pentagonal mirror;

a superimpose-plate that is provided in an incident opening of said hollow pentagonal mirror, said superimpose-plate being put on a focusing glass, on which a subject image obtained through the photographing optical system is formed, a mark, indicated in a picture plane of said view finder, being formed on said superimpose-plate; and

a light-projecting optical system that has a light-projecting plane for projecting an illumination light beam, which is to be radiated onto said mark, into said hollow pentagonal mirror through said emergent opening, said light-projecting plane being located below the optical axis of said ocular optical system.

2. A light-projecting device according to claim 1 , wherein said mark comprises a micro-prism formed on a surface of said superimpose-plate.

3. A light-projecting device according to claim 1 , wherein said light-projecting optical system comprises a light source radiating said illumination light beam, a light-projecting prism reflecting said illuminating light toward said emergent opening, said light-projecting plane being an emergent plane of said light-projecting prism.

4. A light-projecting device according to claim 3 , wherein said light source is disposed close to an upper end of said emergent opening, and said light-projecting prism is disposed below said light source.

5. A light-projecting device according to claim 3 , wherein said light-projecting prism is disposed beside said ocular optical system.

6. A light-projecting device for a view finder, comprising:

a hollow pentagonal mirror;

an ocular optical system that faces an emergent opening of said hollow pentagonal mirror;

a focusing glass that is provided in an incident opening of said hollow pentagonal mirror so that a subject image obtained through a photographing optical system is formed;

a superimpose-plate that is put on said focusing glass, a mark, indicated in a picture plane of said view finder, being formed on said superimpose-plate;

a light source that radiates an illumination light beam; and

a light-projecting prism that reflects said illumination light beam toward said emergent opening, said light-projecting prism having a light-projecting plane; said light-projecting plane being located below the optical axis of said ocular optical system.

7. A light-projecting device for a view finder, comprising:

an ocular optical system that faces an emergent opening of a hollow pentagonal mirror;

a superimpose-plate that is provided in an incident opening of said hollow pentagonal mirror, said superimpose-plate being put on a focusing glass, on which a subject image obtained through the photographing optical system is formed, a mark, indicated in a picture plane of said view finder, being formed on said superimpose-plate, said superimpose-plate being inclined so that an edge, close to said photographing optical system, of said superimpose-plate is lowered; and

a light-projecting optical system that has a light-projecting plane for projecting an illumination light beam, which is to be radiated onto said mark, into said hollow pentagonal mirror through said emergent opening, said light-projecting plane being located beside said ocular optical system.

8. A light-projecting device according to claim 7 , wherein said superimpose-plate is more inclined than said focusing glass.

9. A light-projecting device according to claim 8 , wherein said superimpose-plate is inclined by 1-3 degrees relative to said focusing glass.

10. A light-projecting device according to claim 7 , wherein said superimpose-plate comprises a plane-parallel plate, and an outer frame enclosing said plane-parallel plate, said outer frame being mounted on a focus-adjusting washer that is provided between said superimpose-plate and said focusing glass.

11. A light-projecting device according to claim 7 , wherein said mark comprises a micro-prism formed on a surface of said superimpose-plate.

12. A light-projecting device according to claim 7 , wherein said light-projecting optical system comprises a light source radiating said illumination light-beam, a light-projecting prism reflecting said illuminating light toward said emergent opening, said light-projecting plane being an emergent plane of said light-projecting prism.

13. A light-projecting device according to claim 12 , wherein said light source is disposed close to an upper end of said emergent opening, and said light-projecting prism is disposed below said light source.

14. A light-projecting device for a view finder, comprising:

a hollow pentagonal mirror;

an ocular optical system that faces an emergent opening of said hollow pentagonal mirror;

a focusing glass that is provided in an incident opening of said hollow pentagonal mirror so that a subject image obtained through a photographing optical system is formed;

a superimpose-plate that is put on said focusing glass, a mark, indicated in a picture plane of said view finder, being formed on said superimpose-plate, said superimpose-plate being inclined so that an edge, close to said photographing optical-system, of said superimpose-plate is lowered;

a light source that radiates an illumination light beam; and

a light-projecting prism that reflects said illumination light beam toward said emergent opening, said light-projecting prism having a light-projecting plane, said light-projecting plane being located beside said ocular optical system.