Camera term promenade: 6th: Electronic shutter (Part 2, electric shutter) --Digital camera Watch

From electronic control to electric

As I wrote last time, the "electronic control shutter", which starts with Polaroid Automatic 100, quickly spread due to its good compatibility with exposure control.Electronic control not only for lens shutters but also for focal plene shutters has been developed into TTL-AE and multi-mode AE along with the development of electronics technology.However, the shutter feathers and the driving of the curtain were the same as before, using the power of the spring.

There are several reasons why springs are used to move shutter feathers and curtains.First of all, the old camera does not have a power supply battery.Since 1960, CDS has been used for the light receiving element of the exposure meter, so the battery has been used for the camera, but the small -capacity button -type battery has gained the power to move the shutter very much.do not have.

In the case of silver -salt cameras, it is also a big reason that the cycle of the shooting of the film wound → shutter release fits perfectly with the charging of the spring → release.The "self -cocking" mechanism, which links the winding and charge, allows you to omit the charging movement before shooting and to prevent multiple exposure at the same time.

The biggest reason for using a spring for shutter driving may be the "instantaneous power".Spring is excellent in instantaneous power.Instead, it is rather not good to continue to work continuously.In the case of a clock, this is covered by gradually making the spring (mainspring) power while controlling it with a mechanism called an extermination.In the case of a camera shutter, moving the feathers and curtains quickly requires great power, but the required time ends in an instant, so the spring was a perfect source of power.

On the other hand, the electric motor does not work immediately at the start.There is a delay time from turning on the switch to the operation.And above all, it is too big for built -in camera.However, when the motor technology developed rapidly and a small and well -performance motor appeared, the desire to use it as a shutter driving force increased, and it was first served from the lens shutter.