Middle curtain flash

• US 5,452,048 A
• Filed: 01/19/1994
• Issued: 09/19/1995
• Est. Priority Date: 08/04/1992
• Status: Expired due to Term

• Current Assignee: MediaTek, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Edgar, Albert D.
• Primary Examiner(s): Perkey, W. B.
• Application Number:
  US08/183,643
• Time in Patent Office: 608 Days
• Field of Search: 354/414, 354/137, 354/138
• US Class Current: 396/180
• CPC Class Codes: G03B 9/70 with flash-synchronising contacts

Abstract

A camera system and method for operation of fill flash photography, combining natural and flash light, which centers the times of natural light and flash light images. Synchronization is achieved by centering the time a flash is triggered midway between the opening front curtain and closing rear curtain of the shutter. In a particular preferred embodiment, a digital camera is coupled to a computer forming a system which stores images for image processing. The system includes a means for determining a period during which the shutter of the camera system will be opened and a means to determine a middle period in the the open shutter period. Preferably, the flash is fired at the midway point of the shutter period. This midway point in time is used to trigger the flash so it is substantially centered in time within the shutter period.

Claims

1. In a camera system, a method of timing an electronic flash during a fill flash mode comprising the steps of:

determining a time period during which a shutter of the camera system will be open;

determining a flash fire time substantially midway in the time period for all light conditions; and

in response to beginning the time period, firing the electronic flash at the determined flash fire time in the time period.

2. The method as recited in claim 1 wherein the flash is fired exactly halfway during the time period.

3. A camera system having a flash fill mode comprising:

a means for determining a time period during which a shutter of the camera system will be open;

a means for determining a flash fire time substantially midway in the time period for firing an electronic flash for all light conditions in the flash fill mode; and

,

a timer for controlling the shutter and firing the flash at the flash fire time in response to a signal that the time period has begun.

4. The system as recited in claim 3 wherein the flash is fired exactly halfway during the first time period.

5. A digital camera system having a flash fill mode controlled by a computer system comprising:

a digital camera;

a computer coupled to the digital camera having a processor, a memory and an input device;

a means for determining a time period during which a shutter of the camera system will be open;

a means for determining a flash fire time substantially midway in the time period for firing electronic flash for all light conditions in the flash fill mode; and

,

a timer to control the shutter and the flash in response to a signal that the time has begun.

6. The system as recited in claim 5 wherein the flash is fired exactly halfway during the first time period.