ITT PVS-14 Close Focus Stop

hey guys today we are talking about three properties of night vision devices that you should be familiar with before you start using night vision they are focus diopter and aperture those three properties of the device correspond to three parts of the device the ring at the front controls focus the ring at the back adjusts diopter and the removable daylight cap adjusts the aperture first up focus focus is pretty self-explanatory you can adjust the focus ring on the front of the device to go from anything very close to you all the way up to infinite infinite focus works just fine for anything between about 50 yards and the moon the reason you need to adjust the focus so much on a night vision device is because they have an extremely limited depth of field and the reason that they have such a limited depth of field is due to the aperture aperture is a property of camera lenses but it also