Eyepiece shutter

The eyepiece shutter of a Minolta Dynax 9 when closed. The orange marking ensures that the photographer can immediately see that the eyepiece shutter is closed, even in poor light. The small lever at the top left next to the viewfinder operates the shutter. This design does not differ from other models.

An eyepiece shutter is a device in the viewfinder of SLR cameras with built-in exposure metering and is used to prevent extraneous light from entering the viewfinder when the eye is not at the eyepiece .

The eyepiece lock is usually only found on professional cameras, while other cameras come with a plastic cap that can be pushed onto the viewfinder eyepiece and has the same effect.

The eyepiece shutter is used when taking pictures from a tripod when there is a risk of extraneous light penetrating through the viewfinder from behind and thus falsifying the exposure measurement of the photocell in the camera, instead of just measuring the incidence of light through the lens.

The eyepiece shutter has no function when the camera is close to the eye. Eyepiece caps are usually color-coded so that when you look through the viewfinder you can immediately see whether it is closed or whether the lens cap is accidentally covering the image.