ROSKAM-OPTICS binoculars

ROSKAM-OPTICS offers a broad range of quality binoculars of the brands

• Bresser-Meade/international,
• Docter/Germany,
• Meopta/Czechia,
• Swarovski/Austria,
• Vixen/Japan

All binoculars are waterproof and nitrogen gas-filled to prevent internal fogging. All glass surfaces are multi-layer coated to obtain maximal light transmission and to avoid internal reflection. Differences in prices reflect as well optical quality as mechanical robustness. However, ROSKAM-OPTICS is most competitive offering high quality and service for modest prices.
 

Which binocular do we recommend?
You may distinguish between two main types of binoculars: the classical binoculairs are equipped with porro prisms, the light beam is transmitted in a zig-zag way. More modern (most) binoculars have roof prisms allowing the light beam to pass the binocular in an apparent straight way. Porro binoculars are cheaper than the roof prism types, but are certainly not inferior: the relative simple construction allows a very high level of all kinds of corrections. Moreover, because the distance between the objectives is significantly larger than that of the oculars, the image is more plastic and ‘3 dimensional’. Please browse the superlative test reports for Docter Nobilem binoculars on the web.
Roof prism binoculars have different advantages: the ergonomy is better which results in a more stable image. The main con of roof prisms is that you should correct the distance between the oculars EXACTLY on those of your eyes, otherwise some troublesome colour aberration may occur. The newest ED-binoculars and the top range of Meopta and Swarovski are completely free from colour aberration. But note that for that amount you can buy three pairs of good porro binoculars!.
 

Binoculars consist of two parallel compound optical systems. At front are the objectives, at back the oculars.

The diameter of the objectives determines the brightness of the binocular, the oculars the magnification. If you divides the objective diameter in mm (e.g., 50 mm) by the magnification of the oculars (e.g., 10) you get the exit pupil (5), and squared the brightness (25).

* Objective diameter: the larger, the more light the binocular transmits, but also the heavier the binocular. Binoculars heavier than 800 gr are troublesome if carrying around a whole day. Pocket  binoculars weigh approx. 300 gr. but offer, by definition, a lower brightness and resolution.

* Magnification. Most binoculars are 8 or 10x, marine binoculars 7x. The higher the magnification, the closer the object, but the more shaky the picture: your own body trembling is magnified also! If you have a young stable hand 10x is excellent but if not, you should better use a 8x. For higher than 10x we recommend the use of a tripod.

* Exit pupil/ brightness: the larger the exit pupil, the brighter the binocular. However, the exit pupil should match the pupil width of your own eyes. Experience learns that older users are unable to open their pupils wider than 4 mm, hence, for older users a heavy binocular with a large exit pupil is impressive, but worthless! Nevertheless, compare the image of a bright binocular with that of a compact one. Please note also that expensive and cheap binoculars of the same theoretical brightness do differ significantly in their performance.