Porro or Roof

With roof prisms, the roof prisms (also called pentaprisms) are placed one behind the other. The light passes through the binoculars almost in a linear line. This allows this type of viewer to be more compact in size.

With a porro viewer, the image is transported via an N-shaped bend, where the prisms and the objective and eyepiece are not directly opposite each other, which is why this type is generally wider than the roof viewer. The advantage of this setup is that binoculars with a porro prism offer a little more depth perception.

Magnification and Lensdiameter

Binoculars always have 2 numbers. For example, the numbers 8x42 on binoculars means that the viewer has a magnification of 8x and an objective diameter of 42 mm, this means that the objects you are viewing are brought 8x closer, and that the objectives (the lenses on the front viewer) have a diameter of 42 mm. If the diameter is larger, the binoculars will let in more light, so you have a clearer image. The term diameter objectives is also referred to as effective opening of the front lens.

Field of View

The field of view is the width that can be seen with binoculars at a distance of 1000 meters. This has everything to do with the angle of view that the viewer gives. The greater the viewing angle, the greater the field of view. The field of view can be calculated by multiplying the angle of view by 17.5. A viewer with a viewing angle of 9.3 degrees thus has a field of view at 1000m of 9.3x17.5 = 162.7

Coatings

Coatings prevent reflection and scattering of light. This reduces the loss of light and gives a better contrast. Untreated glass can lose up to 5% light transmission. Binoculars consist of several glass lenses and would therefore lose a lot of light with untreated glass. A single layer of anti-reflection coating can reduce loss by about 1.5%. Through multiple layers of different coatings, the light loss can be reduced to as much as 0.2%. A coating is applied to the glass by evaporating the coating. This is done in a protected environment so that no dirt can come with the coating. A damaged coating cannot be repaired.

Exit Pupil

If you hold binoculars up to the light at a distance of about 30cm from the eye, a circle of light in the eyepieces (the lenses facing the eye) becomes visible. The size of the exit pupil differs per binocular model. The size of the light circle can be calculated by dividing the objective diameter by the magnification. With 8x42 binoculars, the exit pupil is therefore 42/8 = 5.25 mm.

In young people, the pupil of the human eye can open up to about 7mm in the dark, in bright light the pupil closes up to about 2mm. As one gets older, the suppleness of the pupil will decrease, so that the pupil only opens up to about 5mm in the dark.

The foregoing shows that the purchase of binoculars with an exit pupil larger than 8mm provides no added value; after all, the human eye cannot make use of the larger spot of light.

The shape of the exit pupil is also an indication of the quality of the binoculars. When the exit pupil is perfectly round, this indicates a very good quality of the lenses. With poor lens quality, the exit pupil is not perfectly round, but angular or misshapen, resulting in reduced light output and poorer image quality

Almost all binoculars come standard with two sets of caps. These are the lens and eyepiece covers. These are separate accessories and it sometimes happens that they get lost. We have been the binoculars specialist for over 15 years. Started in 2001, so more than extensive experience in the sale, repair and service of binoculars, spotting scopes and associated accessories. We are official dealer of Swarovski, Zeiss, Leica, Steiner, Vortex, Kahles, GPO, Bynolyt, Meopta, Pentax, Hawke and Bushnell.

Binoculars Caps

We have both eyepiece and lens caps in stock for many brands as standard. We can send this to you or you can pick it up in our store. It is recommended to contact us by e-mail. Please state your binoculars model. Not sure what kind of binoculars you have? No problem, we often come a long way with a few photos.

Binoculars Rubber

When the eyepiece rubber of your binoculars is missing, this can be a real obstacle. Most brands offer as a service to replace it free of charge. However, this is not always the case. For the possibilities, it is best to contact us.