[Hitman]

Fixed 7x for the binoculars? Really? I wonder why the UZO and binoculars were the same power rating?

Very easy:

GENERAL NOTES:

A marine binocular is a binocular that is used onboard a ship or boat and as such, it will have some fairly specific features. The vast majority of marine binoculars will be the classic 7x50, although other sizes can be used if they have the necessary features.

MAGNIFICATION - (the first number in a binocular)

- Because the deck of a ship or boat is not a stable observing platform, magnification must be kept low for the sake of steadiness. 7x is by far the most popular magnification in a marine binocular and for good reason. A 7x binocular is easy to hold but also powerful enough to be a serious observation tool. Higher magnifications can be used, but unless they are combined with IS (image stabilization) systems, any gain in image detail may be lost to image unsteadiness. In fact, under marginal conditions, you may see more detail with a steady 7x than a shaky 10x.

OBJECTIVE SIZE - (the second number in a binocular)
- The classic 7x50 marine binocular will have a 50mm lens. This is not just a matter of image brightness, though for night use, the 50mm objective will transmit more light than smaller objective. A 50mm objective, when combined with 7x magnification also produces a large exit pupil - the beam of light that leaves the eyepieces. This large exit pupil is much more forgiving than a smaller exit pupil when the eyes are not lined up precisely on the eyepieces, as might happen when you try to observe form the deck of a moving boat.

PRISM TYPE

- The classic 7x50 marine binocular is a porro prism, though, optically there is no reason a roof prism could not be used. The porro prism body, however, has more room to accommodate extras like a rangefinder and compass that are often found on a marine binocular. The robust body of a porro prism may also provide a firmer grip during inclement weather. The best porro prisms will be made of Bak-4 glass.

FOCUS TYPE

- Both IF (individual eyepiece focus) and CF (center focus) systems are found on marine binoculars.
- IF offers the freedom from focusing when viewing objects at medium and long distances - the usual range for marine use. Once set for your eyes initially, an IF binocular needs no focusing for objects beyond 30 or 40 yd. Just raise the binocular to your eyes and look. The advantage on the deck of a moving boat is obvious here. IF focusing systems are also the easiest to seal and make waterproof and they have fewer moving parts than CF systems. For this reason, they are also popular with the military. (Our military uses a version of the Steiner 7x50)
- Center focus is a more versatile system. If you plan to use a binocular at all ranges, from close-in to far away, say for birding or other applications, this is the system to choose.