Product information: “Knobloch Iris Shutter”
The iris shutter for shooting glasses from Knobloch is ideal for pistol or rifle shooters, who shoot with open adjustment. This replaces the diopter and improves the focus (depth of field). It is put on the lens-holder from behind to avoid disturbing reflexes in the lens. It can be used for right or left aiming shooters. Iris shutters are available for big and small lens-holders.
Tip: First of all, you should achieve the right correction for the aiming eye then you can increase the sharpness with the iris shutter.