Camera and exposure control method

An exposure control method for a roll photo film, said roll photo film including a photo filmstrip having an effective exposure region in which plural frames are formable one after another, a light-shielding leader disposed on a front end of said photo filmstrip, a light-shielding trailer disposed on a rear end of said photo filmstrip, said roll photo film being pre-wound with said trailer wound inwards and with said leader wound outwards, and including a bar code, prerecorded between a front end of said leader and said effective exposure region, for representing photo film information including information of an auto input photosensitivity value, said exposure control method comprising steps of:

• winding said roll photo film about a take-up spool to which said front end of said leader is retained;
• detecting an axial rotating amount of said take-up spool, said axial rotating amount corresponding to a transported amount of said roll photo film;
• detecting a reflection level of said bar code at a photo sensor;
• obtaining a distance where said reflection level of said bar code is stable by referring to said axial rotating amount in response to a signal from said photo sensor, so as to obtain a width of said bars;
• reading said bar code to detect said auto input photosensitivity value;
• selecting one of automatic and manual modes, said auto input photosensitivity value being rendered effective when selecting said automatic mode, and rendering a manual input photosensitivity value being rendered effective when selecting said manual mode, said manual input photosensitivity value being determinable through a variable photosensitivity input unit;
• and
• controlling an amount of exposure to said effective exposure region in accordance with an effective one of said auto and manual input photosensitivity values.

A camera for use with a roll photo film, said roll photo film including a photo filmstrip having an effective exposure region in which plural frames are formable one after another, a light-shielding leader disposed on a front end of said photo filmstrip, a light-shielding trailer disposed on a rear end of said photo filmstrip, said roll photo film being pre-wound with said trailer wound inwards and with said leader wound outwards, and including a bar code, prerecorded between a front end of said leader and said effective exposure region, for representing photo film information including information of an auto input photosensitivity value, said camera comprising:

• a camera body;
• a bar code reader for reading said bar code to detect said auto input photosensitivity value;
• a variable photosensitivity input unit, externally operable, for inputting a manual input photosensitivity value;
• a mode selector, externally operable, for selecting one of automatic and manual modes, said mode selector rendering said auto input photosensitivity value effective when selecting said automatic mode, and rendering said manual input photosensitivity value effective when selecting said manual mode;
• an exposure control unit for controlling an amount of exposure to said effective exposure region in accordance with an effective one of said auto and manual input photosensitivity values;
• a memory for storing said auto input photosensitivity value read by said bar code reader, wherein when said automatic mode is selected in said mode selector, said auto input photosensitivity value is read from said memory as effective;
• a photo film take-up chamber, formed in said camera body;
• a photo film loader chamber, formed in said camera body, and loaded with said roll photo film;
• and
• an exposure aperture, formed in said camera body and disposed between said loader chamber and said take-up chamber, for providing said effective exposure region with an exposure;
• wherein said bar code reader is disposed between said exposure aperture and said loader chamber, and reads said bar code while said leader is wound into said take-up chamber and before a first one of said frames of said effective exposure region is set on said exposure aperture.

A camera for use with a roll photo film, said roll photo film including a photo filmstrip having an effective exposure region in which plural frames are formable one after another, a light-shielding leader disposed on a front end of said photo filmstrip, a light-shielding trailer disposed on a rear end of said photo filmstrip, said roll photo film being pre-wound with said trailer wound inwards and with said leader wound outwards, and including a bar code, prerecorded between a front end of said leader and said effective exposure region, for representing photo film information including information of an auto input photosensitivity value, said camera comprising:

• a photo film take-up chamber, formed in said camera body;
• a photo film loader chamber, formed in said camera body, and adapted to be loaded with said roll photo film;
• an exposure aperture, formed in said camera body and disposed between said loader chamber and said take-up chamber, for providing said effective exposure region with an exposure;
• a bar code reader disposed between said exposure aperture and said loader chamber for reading said bar code to detect said auto input photosensitivity value;
• a variable photosensitivity input unit, externally operable, for inputting a manual input photosensitivity value;
• a mode selector, externally operable, for selecting one of automatic and manual modes, said mode selector rendering said auto input photosensitivity value effective when selecting said automatic mode, and rendering said manual input photosensitivity value effective when selecting said manual mode;
• an exposure control unit for controlling an amount of exposure to said effective exposure region in accordance with an effective one of said auto and manual input photosensitivity values
• a rotatable photosensitivity dial, having a train of numerals arranged near to a periphery thereof for representing manual input photosensitivity values;
• and
• a pointer, disposed near to said photosensitivity dial and directed thereto, said photosensitivity dial being rotated to set one numeral of said numeral train at said pointer, said manual input photosensitivity value being selected according to said one numeral being set;
• said mode selector including an auto input indicia, disposed on said photosensitivity dial in addition to said numeral train, for selecting said automatic mode when set at said pointer.