Fairchild MARK 5 MOD 0 lens. Manufacured by the Fairchild Camera and Instrument Corp. Defense Products Division for the Navy Department Bureau of Naval Weapons, this high quality optical unit was intended to be mounted to aircraft. With four 6 volt lantern batteries wired together in series, you can turn on the two smaller wide angle lenses and focus them at varying distances, and, see the view the big mirror lens view in the focusable eypiece... AT THE SAME TIME!!! The photograph of the tree demonstrates this. The close up of the tree is seen with the big lens, the wide angle view with the picnic table next to the same tree is there also. The photo of two people near the cross on the rock bluff was taken from 4 miles away with the green filter on. The system has a green and red filter. The photo of the Sun was taken using the red filter. A mountain 50 miles away will apear to be 2 miles away with this scope yet it will resolve objects as close as 3 feet away with clarity and sharpness. The quality of the optics in this unit are very good. The photos were taken with a Panasonic Lumix digital camera into the Fairchild's eyepiece which does not do it justice. The Fairchild looks alot better with the naked eye rather than the Panasonic's lens. There is a Dry Nitrogen valve on the weatherproof Fairchild MARK 5 to prevent fogging. There is a manual elevation adjustment, filter selector, and f stop control. The eyepeice unscrews and a still or video camera mount can be machined to fit. Under certain conditions and distances crosshairs appear with either a diamond or square or both. Fairchild made a 4 stereo pair camera/lens unit that photographed the Moon on the NASA Appollo mission. Northrup, a competitor with Fairchild for government contracts, made the Axx-1 lens system. The Axx-1 is similar to this Fairchild MARK 5, it is connected to radar and mounted under the nose of the Navy's F14 Tomcat. I got this Fairchild unit a few years ago new in the box. Since then I have taken a few photographs through it, otherwise it has been in storage and is like new. Email for more photos and specs. Location: Boise it's NOT ok to contact this poster with services or other commercial interests idaho