AUTO IRIS.
A fundamental facilitation of the photographer's work, controlling the image on the focusing screen through the lens until the last moment, there are priority and automatic apertures.
Pre-selective apertures consist in building an additional ring into the lens, which we set to the aperture size selected for the photo and then move the ring like this, to fully open the aperture. At the last moment, it is enough to turn the ring until it stops without looking at the aperture scale, to obtain the preset aperture size. This device provides much faster work speed, because it does not require taking the camera away from the eye and reading the aperture scale; one hand movement is enough ,,blindly”.
Auto iris is a further development of the same principle. This is what they do, that we view the image through the lens fully open, but the moment you press the shutter button, the aperture automatically adjusts to that size, previously set on the aperture scale. This device, operating automatically, eliminates the greatest difficulty in working quickly with a mirrorless camera, i.e. setting the appropriate aperture at the last moment before the shutter release and controlling the image on the focusing screen using the previously set aperture.
Drawing. Automatic iris suitable for Exakta and Exa cameras.
The currently commonly used system consists in the incorporation of a lever (drawing) the aperture adjusting mechanism, combined, directly with the shutter release device like this, that no matter how you set the scale to the desired aperture size, it stays fully open all the time. It is only when the shutter is pressed that it closes to the set size and after releasing the pressure on the shutter, it returns to full aperture by means of a spring..