The Seago MON842 is a light weight heavy duty monocular incorporating a hand bearing compass and range finder. Waterproof testing standard means are sealed against water incursion in 1 metre of water for 30 minutes. These monocular are nitrogen filled to avoid misting and float in case dropped over-board. They come in a durable protective carry case.
Objective lens dia: 42mm
Field angle: 7 degrees
Exit pupil: 5.3mm
Eye relief: 19mm
Prism type: Porro BAK-4
Field of view: 122m at 1000m
Lens coating: Multi coating
** COMPASS ZONE B: Areas between 40 degrees North latitude and 60 degrees North latitude
Colour Black/ Blue
Materials Durable plastic/ Rubber
Special features Rubber grips, waterproof, floating, nitrogen charged, hand bearing compass, range finder, rubber lens, caps, carry bag
Exit Pupil Diameter 5.3mm
Eye Relief 19mm
Weight 360g Monocular only
Dimensions 145mm x 65mm
What is a Rangefinder Reticle?
A reticle or reticule is a net of fine lines or fibers in the eyepiece of the binocular, monocular, microscope, scope or other optical device used for sighting and taking other measurements.
Rangefinder reticles are obviously used to calculate the distance between you and an object you are observing, but can also be used to calculate the height of an object or the included angle of a viewed object.
How do Rangefinder Reticles work?
There are actually a few systems to calculate distance used in rangefinder reticle binoculars and scopes. The simplest and most commonly used involves comparing a scale or measuring marks on the reticle in the binocular, monocular or the scopes field-of-view against a known sized portion or the whole object that you are looking at. In military and hunting circles this is often referred to as the Mil-Dot reticle and the formula for working out the distance is known as the Mil-dot formula:
So if you know the height or length of the object you can calculate the distance away from that object with some simple maths. Or you can also calculate the height or length of the object if you know the distance you are away from it.
So if you were sailing on a yacht and looked through your reticle rangefinder binoculars at a lighthouse that you knew to be 60 meters tall:
Distance = Height of the Target/Scale Height 1000
Distance = 60 / 80 1000
Distance to the lighthouse = 750m
Do Rangefinder Reticles Work?
Yes, but in terms of providing an exact distances, they aren t as accurate or fast as a laser rangefinders, but they can give you a good idea and work over long distances.
How accurate they are depends on the user lining up the target and of course how accurate you are when estimating the height or length of the target. If you know the exact height of the target and line it up very carefully on the reticle, they will be very accurate.
So as boating binoculars and other marine uses, reticle rangefinders are in most cases the best solution, but because laser rangefinders have become more compact and affordable they are often now more commonly used for most golf rangefinders and hunting binoculars and scopes.