Flash photographing system

• US 4,494,850 A
• Filed: 06/16/1983
• Issued: 01/22/1985
• Est. Priority Date: 06/21/1982
• Status: Expired due to Term

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Yamada, Masanori, Kawamura, Masaharu, Katsuma, Makoto
• Primary Examiner(s): Perkey, William B.
• Application Number:
  US06/505,082
• Time in Patent Office: 586 Days
• Field of Search: 354/416, 354/417, 354/429, 354/431, 354/480, 354/481, 354/483
• US Class Current: 396/61
• CPC Class Codes: G03B 7/16 in accordance with both the intensity of the flash source and the distance of the flash source from the object, e.g. in accordance with the "guide number" of the flash bulb and the focusing of the camera
• CPC Class Codes: G03B 7/17 Selection of modes in flash units by exposure control arrangements

Abstract

The disclosed flash photography system operates in a first mode by controlling the flash on the basis of the distance information signals, and in a second mode by controlling the flash in response to the flash illumination of the object to be photographed. The system insures accurate flash photography by shifting from the first mode to the second mode when the camera uses a lens with a short focal length or with an attached filter.

Claims

1. A flash photography system comprising a flash device and a camera, said system including:

(a) distance information signal forming means for forming information on a distance to an object to be photographed;

(b) a flash exposure degree control circuit arranged to operate either in a first mode in which the degree of flash light exposure is controlled on the basis of the distance information from said distance information signal forming means or in a second mode in which a quantity of reflected light coming from the object as a result of illumination of the object by a flash from the flash device is detected and the degree of flash exposure is controlled on the basis of the detected quantity of the reflected light;

(c) detecting means for detecting information on the focal length of a photo-taking lens mounted on the camera; and

(d) a selection circuit arranged to select the first mode of the flash exposure degree control circuit when the focal length detected by said detecting means is longer than a prescribed focal length and to select the second mode when the detected focal length is shorter than the prescribed focal length.

2. A flash photographic system according to claim 1, wherein said flash light exposure degree control circuit, in the first mode, controls a time for terminating flash light generation by said flash device on the basis of said distance information and, in the second mode, terminates the flash light generation by said flash device when said quantity of the reflection light from the object reaches a prescribed value.

3. A flash photography system comprising:

(A) a flash device having;

(a) flash means; and

(b) a flash quantity control circuit arranged to perform either a first flash quantity control function in which the quantity of light is controlled on the basis of distance information or a second flash quantity control function in which the quantity of light is controlled on the basis of reflected light coming from an object to be photographed as a result of illumination of the object by a flash from the flash mean; and

(B) a camera having;

(a) detecting means for detecting information on the focal length of a photo-taking lens mounted on the camera; and

(b) selecting means for selecting said first function when the focal length detected by said detecting means is longer than a prescribed focal length and for selecting said second function when the detected focal length is shorter than the prescribed focal length.

4. A flash photography system according to claim 3, wherein said flash quantity control circuit includes a control portion which controls a time for terminating flash light generation by said flash means;

said control portion being arranged to control the flash generation terminating time either on the basis of said distance information or on the basis of information on said reflected light coming from the object through a photo-taking lens as a result of illumination of the object by the flash; and

said selecting means being arranged to transmit said distance information to said control portion when the detected focal length is longer than the prescribed focal length and to transmit said information on said reflection light to the control portion when the detected focal length is shorter than the prescribed focal length.

5. A flash photography system comprising:

(A) a flash device having;

(a) flash means; and

(b) a flash quantity control circuit having a first flash quantity controlling function which is to be performed in accordance with a first flash exposure degree control mode based on distance information and a second flash quantity controlling function which is to be performed in accordance with a second flash exposure degree control mode based on the quantity of a reflected light coming from an object to be photographed as a result of illumination of the object by said flash means; and

(B) a camera having;

(a) detecting means for detecting information on the focal length of a photo-taking lens mounted on the camera;

(b) a flash exposure degree control circuit arranged to operate either in said first or second flash light exposure degree control mode; and

(c) selecting means for selecting said first mode and said first function when the focal length detected by said detecting means is longer than a prescribed focal length and for selecting said second mode and said second function when the detected focal length is shorter than the prescribed focal length.

6. A flash photographing system comprising:

(A) a flash device having;

(a) flash means; and

(b) an adjusting circuit arranged to adjust the quantity of light generated by said flash means; and

(B) a camera having;

(a) detecting means for detecting information on the focal length of a photo-takng lens mounted on the camera;

(b) a flash exposure control circuit arranged to operate either in a first mode in which the light generation quantity to be adjusted by said adjusting circuit is determined on the basis of information on a distance to an object to be photographed or in a second mode in which a quantity of reflected light coming from the object as a result of illumination of the object by a flash light from the flash device is detected and the flash light generation quantity to be adjusted by said adjusting circuit is determined on the basis of the detected quantity of the reflected light; and

(c) selecting means for selecting said first mode when the focal length detected by said detecting means is longer than a prescribed focal length and for selecting said second mode when the detected focal length is shorter than the prescribed focal length.

7. A camera adapted for use with a flash device including flash means and an adjusting circuit for adjusting the quantity of light emission from said flash means, said camera comprising:

(a) light receiving means for receiving reflected light coming via the aperture of a photo-taking lens from an object to be photographed as a result of light emission from said flash means;

(b) detecting means for detecting the focal length of said photo-taking lens;

(c) a control circuit arranged to cause said adjusting circuit to adjust the quantity of light emission either on the basis of the output of said light receiving means or on the basis of a distance to the object; and

(d) selecting means for having said control circuit cause said adjusting circuit perform said adjustment on the basis of the object distance when the focal length detected by said detecting means is longer than a prescribed focal length or on the basis of the output of said light receiving means when the detected focal length is shorter than the prescribed focal length.

8. A camera usable with a flash device arranged to adjust the flash devices light quantity on the basis of information on the distance to an object to be photographed, said camera comprising:

(a) light receiving means for receiving reflected light coming via the aperture of a photo-taking lens from an object to be photographed as a result of flash light emission by said flash means;

(b) detecting mcans for detecting the focal length of said photo-taking lens; and

(c) selecting means for causing said flash device to adjust the light quantity on the basis of the output of said light receiving means instead of the information on the distance to the object when the focal length detected by said detecting means is shorter than a prescribed focal length.

9. A photographic camera adapted for use in a flash photography system which includes the camera and a flash device provided with an adjusting circuit for adjusting the quantity of light emission and is arranged to control the degree of exposure for flash photography on the basis of information on the distance to an object to be photographed, said camera comprising:

(a) light receiving means for receiving reflected light coming via the aperture of a photo-taking lens from an object to be photographed as a result of light emission by said flash device;

(b) detecting means for detecting the focal length of said photo-taking lens; and

(c) a change-over circuit for shifting the control of the degree of exposure by said adjusting circuit from the control based on the object distance information to control based on the output of said light receiving means, said change-over circuit being arranged to cause said adjusting circuit to adjust the quantity of light emission on the basis of the output of said light receiving means when the focal length detected by said detecting means is shorter than a prescribed focal length.

10. A flash device comprising:

(a) flash means; and

(b) a control circuit operable in a distance light adjusting mode and a second light adjusting mode in which the control circuit adjusts the quantity of light on the basis of a quantity of a light reflected by an object to be photographed as a result of a flash from said flash means, said control circuit being arranged to perform flash exposure control in said distance light adjusting mode when the focal length of a photo-taking lens mounted on a camera as detected by focal detecting means is longer than a prescribed focal length and in said second mode when said detected focal length is shorter.

11. A flash photography system including a flash device and a camera, said system comprising:

(a) distance information signal forming means for forming information on a distance to an object to be photographed;

(b) a flash exposure degree control circuit arranged to operate either in a first mode in which the degree of flash exposure is controlled on the basis of the distance information from said distance information signal forming means or in a second mode in which a quantity of light reflected by the object as a result of illumination of the object by light from the flash device is detected and the degree of flash exposure is controlled on the basis of the quantity of the reflection light detected; and

(c) a change-over circuit arranged to shift the mode of said flash exposure degree control circuit from the first mode to the second when an accessory varies the quantity of a light transmitted through the photo-taking lens of the camera is mounted with the lens.

12. A system as in claim 11, wherein said accessory is a filter.

13. A system as in claim 11, wherein said assessory is an intermediate adapter.

14. A flash photography system comprising:

(A) a flash device having;

(a) flash means; and

(b) a flash quantity control circuit having a first flash quantity controlling function which is to be performed in accordance with a first exposure degree control mode based on distance information and a second flash quantity controlling function which is to be performed in accordance with a second flash exposure degree control mode based on a quantity of light reflected by an object to be photographed as a result of illumination of the object of said flash means; and

(B) a camera having;

(a) a flash exposure degree control circuit arranged to operate either in said first or second flash exposure degree control mode; and

(b) a change-over circuit arranged to shift the function and the mode of said flash exposure degree control circuit from the first function and mode to the second function and mode when an accessory that varies the quantity of a transmission light passing through the photo-taking lens of the camera is mounted with the lens.

15. A system as in claim 14, wherein said accessory is a filter.

16. A system as in claim 14, wherein said accessory is an intermediate adapter.

17. A flash photography system comprising:

(A) a flash device having;

(a) flash means; and

(b) a flash quantity control circuit arranged to perform either a first flash quantity controlling function in which the quantity of flash is controlled on the basis of distance information or a second flash quantity controlling function in which the quantity of flash is controlled on the basis of a light reflected by an object to be photographed as a result of illumination of the object by a flash light from the flash means; and

(B) a camera having;

(a) a change-over circuit arranged to shift the function of said to flash light exposure degree control circuit from the first function to the second when an accessory that varies the quantity of light transmitted through the photo-taking lens of the camera is mounted with the lens.

18. A system as in claim 17, wherein said accessory is a filter.

19. A system as in claim 17, wherein said secondary is an intermediate adapter.

20. A flash photography system comprising:

(A) a flash device having;

(a) flash means; and

(b) an adjusting circuit arranged to adjust the quantity of flash light generated by said flash means; and

(B) a camera having;

(a) a flash exposure control circuit arranged to operate either in a first mode in which the generated light quantity to be adjusted by said adjusting circuit is determined on the basis of information on a distance to an object to be photographed or in a second mode in which a quantity of light reflected by the object as a result of illumination of the object by a flash light from the flash device is detected and the generated light quantity to be adjusted by said adjusting circuit is determined on the basis of a quantity of the reflected light detected; and

(b) a change-over circuit arranged to shift the mode of said flash light exposure control circuit from the first mode to the second when an accessory that varies the quantity of a transmission light passing through the photo-taking lens of the camera is mounted on the lens.

21. A system as in claim 20, wherein said accessory is a filter.

22. A system as in claim 20, wherein said accessory is an intermediate adapter.

23. A photographic camera adapted for use with a flash device including flash means and an adjusting circuit arranged to adjust the quantity of light emission from said flash means, said camera comprising:

(a) light receiving means for receiving reflected light coming via the aperture of a photo-taking lens from an object to be photographed as a result of flash light emission by said flash means;

(b) detecting means for detecting the focal length of said photo-taking lens; and

(c) a change-over circuit arranged to shift the control mode of said adjusting circuit from operation on the basis of the distance to the object to operation on the basis of the output of said light receiving means when an accessory that varies the quantity of light passing through the photo-taking lens of the camera is mounted with the lens.

24. A camera as in claim 23, wherein said accessory is a filter.

25. A camera as in claim 23, wherein said accessory is an intermediate adapter.

26. A photographic camera usable with a flash device arranged to adjust flash light quantity on the basis of information on the distance to an object to be photographed, said camera comprising:

(a) light receiving means for receiving a reflection light coming via the aperture of a photo-taking lens from an object to be photographed as a result of flash light emission by said flash means; and

(b) a change-over circuit arranged to shift the operating mode of said flash device from said adjustment of the flash light quantity performed on the basis of information on the object distance to adjustment thereof to be performed on the basis of the output of said light receiving means when an accessory such as a filter or an intermediate adapter or the like that varies the quantity of a transmission light passing through the photo-taking lens of the camera is mounted on the lens.

27. A camera as in claim 26, wherein said accessory is a filter.

28. A camera as in claim 26, wherein said accessory is an intermediate adapter.

29. A camera adapted for use in a flash photographing system which includes the camera and a flash device provided with an adjusting circuit for adjusting light quantity and is arranged to control the degree of exposure of flash photography on the basis of information on the distance to an object to be photographed, said camera comprising:

(a) light receiving means for receiving reflected light coming via an aperature of a photo-taking lens from an object to be photographed as a result of light emission by said flash means; and

(b) a change-over circuit for shifting said flash exposure control from the control to be performed on the basis of the object distance information to a control to be performed on the basis of the output of said light receiving means, said change-over circuit being arranged to cause said adjusting circuit to adjust the flash light quantity on the basis of the output of said light receiving means when an accessory that varies the quantity of light passing through the photo-taking lens of the camera is mounted with the lens.

30. A camera as in claim 29, wherein said accessory is a filter.

31. A camera as in claim 29, wherein said accessory is an intermediate adapter.

32. A flash device comprising:

(a) flash means; and

(b) a control circuit having a distance light adjusting mode and a second light adjusting mode in which the control circuit adjusts the quantity of light on the basis of a reflected light coming from an object to be photographed as a result of a flash by said flash means, said control circuit being arranged to perform flash exposure control by shifting said distance light adjusting mode to said second light adjusting mode when an accessory that varies the quantity of a transmission light passing through the photo-taking lens of a camera is mounted on the photo-taking lens.