What is a mono viewer?
A mono viewer works the same as a pair of binoculars only for one eye. The mono viewer is hereby often more compact than binoculars, but you can still get everything close at a distance.
Mono viewer: getting everything close with one eye
In addition to being much more compact than binoculars, the mono viewer also has the advantages that the weight is lower and is an advantage if you have an eye defect or poor vision on one eye, a mono viewer also works better.
With a mono viewer you have a 2-dimensional image where the second also adds a kind of depth that creates a 3-dimensional image.
Just as with binoculars, the most important points are the magnification and the diameter of the lens. Most mono viewers have a magnification between 4 and 12 times and an objective diameter between 20 mm and 42 mm. The most common magnification is 8 or 10x where you can easily keep the image stable and the field of view is also good. This allows you to properly locate and track everything remotely.
As the magnification increases, you have to be careful that it becomes more difficult to keep the image stable and part of the brightness will be lost and the field of view will become smaller.
Also important for a mono viewer that you will use outside is that it is water and dustproof, the material used and the type of coating for the lenses.