Optics glossary


The reticle or crosshairs in the scope provides a target reference. Steiner offers various reticles specifically for hunting, tactical and precision shooting

Resolving power

The resolving power indicates the ability to recognize details and thus the sharpness of the image. The resolution also depends on the magnification factor. In general, the higher the magnification, the more detailed the image. In fact, the resolving power depends on the optical quality of the individual optical components, but general weather conditions and the eyesight of the user also have an influence.

Pupillary distance

The distance from the eyepiece to the human eye at which the full field of view of the product is seen. An extended eye relief allows the user to use the entire field of view even with glasses. Extremely long eye relief should be chosen for riflescopes in order to avoid contact with the face/eye during recoil.


Designation for the connection between the eyepiece and the viewer's eye. Thanks to their ergonomic shape, STEINER eyecups offer maximum observation comfort and prevent disruptive side light. They automatically adapt to the shape of the face, and the binoculars can also be held more still. Thanks to the use of age-resistant silicone, STEINER eyecups are pleasantly soft, kind to the skin and, thanks to their foldable design, are also ideal for people who wear glasses.

Exit pupil

The exit pupil is located just in front of the eyepieces and ideally matches the diameter of the viewer's eye pupil. The formula for calculating the diameter: Lens diameter : Magnification number! The larger the diameter of the exit pupil, the better the vision result in twilight, since the human eye pupil widens the more in low light (approx. 7mm in young people; approx. 5mm from the age of 50). During the day, a diameter of approx. 2 to 4 mm is sufficient. However, the exit pupil says nothing about the quality of binoculars.

Ballistic curve

The ballistic curve describes the trajectory of the projectile after leaving the gun barrel. The trajectory of the ball corresponds to an arc, which always depends on the weight and the exit speed of the ball.

Image or focal plane

A plane perpendicular to the major axis of a lens or mirror, on which the best (sharpest) image of an object is presented.

Spectacle wearer eyepiece

STEINER binoculars have soft eyecups that can be conveniently folded down. As a result, spectacle wearers have the ideal distance to the eyepiece and can use the entire field of view. The small overhang of the folded eyecups enables the eyepiece to be attached to the glasses quietly and comfortably. Scratching the glasses is impossible.

ClicLoc carrying strap connection

With the well thought-out STEINER strap mount, the binoculars always sit securely in the strap. The belt can be loosened and reattached with a flick of the wrist. This clever quick-change system enables the exchange of different risers, e.g. from comfort to floating straps, in seconds.

Click Value

The click value is the size by which you can change the reticle position by turning the adjustment turrets. It is given in MOA, cm or MIL. Each click changes the hit point position by the specified value. If your turrets are protected with caps, you will often find the subdivision information inside the protective caps.

Roof prisms

Prism system for correcting the image delivered by the lens to the eyepiece in reverse and upside down. The use of roof prisms allows the incidence of light to be almost linear, although the light waves are slightly shifted. Due to the arrangement of the roof prisms, however, these binoculars can be designed to be particularly slim and handy.

Twilight number

Calculated measure of the visual performance of binoculars in low light. Formula: square root of (lens diameter x magnification). An additional performance-enhancing feature of the glass, e.g. B. through the remuneration, is not taken into account here.

Dielectric mirror

The roof prism system of the STEINER Wildlife XP 10x44 and 8x44 includes a specially developed dielectric mirror and is coated with a phase correction coating. This high-tech phase correction enables precise detail resolution and color fidelity. The specially developed dielectric mirror in the roof prism system of the Wildlife XP 10x44, 8x44 can reflect up to 99% of the incident light. In addition, the dielectric mirrors also prevent aging of the coating, which can otherwise lead to a deterioration in light transmission over a longer period of time. With this optic, contours are always clearly recognizable, even in poor visibility or when dusk is falling.

Distance Control System

The distance control system guarantees quick and easy detection of animals and birds. Focusing takes place even before the binoculars are on the eye. The distance control system gives you 2 options according to a preset described in the operating instructions. 1. If you see a bird at an estimated distance of 10 m, for example, you can set 10 m directly on the scale and only have to make the fine adjustment. This leaves you with more valuable time for the actual determination. 2. Or you can read the rough distance of a focused object directly on your distance scale. You can read the distance to the animal in the binoculars at any time during the observation.


The diopter is a unit of measurement for the refractive power of optical lenses. A lens with the focus at 1 m has the refractive power of 1 diopter. Lenses with a shorter focus have a higher diopter number. In other words, a lens with a focus at 25 cm has a value of 4 dioptres. The power of convex lenses is always positive, while concave lenses have negative power.

Steiner Precision Setting

The STEINER Wildlife XP 10x44, 8x44 allows you to focus both eyepieces individually. With the direct setting on the eyepieces, a perfect image is created for both eyes. With the double diopter setting, even strong differences in visual acuity between the eyes can be compensated. Simply adjust the prescription once per eye and you will always see clearly without any readjustment. If you are not visually impaired, simply zero the eyepiece rings and you're done.

Rotating eyecups

The Steiner twist-up eyecups are self-locking to always provide the optimal distance to the eyepiece, a. for spectacle wearers. The three stages of the twist-up eyecups enable an ergonomic, a classic-cylindrical and a spectacle-wearer position. If the eyecups do not fit snugly, they can be fine-tuned with the eyecup fine adjustment mechanism. The ergonomic part of the twist-up eyecups offers optimal protection against stray light coming in from the side. They not only simply eliminate annoying reflections, they also ensure an extremely bright image.

Anti-reflective coating/coating

The optical elements of the rifle scope are anti-reflective to reduce the loss of light due to internal reflection. As a result, light transmission, as well as color fidelity and contrast can be improved. Anti-reflective coatings can be divided into quality levels as follows: single anti-reflective, broadband anti-reflective and multiple broadband anti-reflective. Single anti-reflective lenses offer the lowest quality level, multiple broadband anti-reflective lenses the highest. With every Steiner product you get multiple broadband anti-reflection coatings for maximum viewing pleasure.


Technology specially designed for the close-up range (from approx. 2 m), which enables fast and comfortable focusing thanks to stepless, damped focusing. STEINER binoculars are also equipped with the XL focusing wheel, which ensures easy handling even when wearing gloves.

Fluoride glass

New types of glass containing fluoride, which consist largely of the mineral calcium fluoride, improve the contrast depth and color fidelity of the image. The images are razor-sharp and of the highest contrast right to the edge. Contours are always clear and clearly visible, stray light is reduced to a minimum. In contrast to conventional optical glasses, aberrations and color errors are decisively corrected, resulting in very bright images with sharp contours and natural colors. STEINER Wildlife XP 10x44, 8x44 models are equipped with fluoride lenses.

High-contrast optics

STEINER's coating technology for economy series, which offers a very good price-performance ratio, especially for beginners and passionate hobby observers. STEINER's special filtering or amplification of individual color spectra results in bright, sharp-contour image quality - even in blinding sun or early twilight!

High definition optics

STEINER's specially developed optics technology for Expert series, which ensures first-class light transmission through a highly complex coating technology. Perfectly tailored to the respective area of application, e.g. B. glaring sunlight, strong blue reflections at sea, green and brown backgrounds in nature or twilight shadows to compensate. This guarantees the observer reliable light intensity and depth-of-focus image resolution even in difficult weather conditions, while the natural coloring of the object is always retained. Stray light is reduced to a minimum. Even when darkness sets in, details that are no longer visible to the naked eye remain visible.

Ultra high definition optics

STEINER Ultra HD optics deliver the highest level of manufacturing precision and high-quality fluoride glass for absolutely natural color reproduction, maximum resolution and optimal contrast. Unique, precise resolution of details and razor-sharp display right up to the edge of the picture combined with top-class light transmission. 3D brilliance with impressively three-dimensional images, excellent depth of field and XL field of view for the perfect overview in every situation.

Compass zones

There are five different world zones because different magnetic forces have to be taken into account. Only at the equator do the field lines run horizontally (inclination = 0°), at the poles the inclination reaches almost 90° - in between there are all intermediate values. In the northern hemisphere the north pole of the compass rose is "pulled down", in the southern hemisphere the south pole.


Geometric light intensity: arithmetic measure for the brightness value of binoculars. The higher the light intensity, the better the binoculars are suitable for twilight. Calculation formula: Divide the lens diameter number by the magnification number. Square the result. Relative light intensity: While the geometric light intensity only takes into account the lens diameter and the magnification, the relative light intensity describes the additional increase in performance through special types of coating and indicates a percentage increase (e.g. 60%) compared to uncoated glass.


With indestructible stability, STEINER binoculars withstand even the toughest demands! The use of Makrolon® and the compact special construction give the binoculars extreme robustness. Makrolon® is a high-tech material from aerospace, which is characterized in particular by its resistance to corrosion and temperature.

Memory eyepieces

Viewing comfort par excellence: Allows you to easily save your personal focus setting — a significant advantage in the twilight or when the binoculars are used by several people.


MIL is an angular specification with 1 unit of latitude per 1000 units of length, for example 1m distance in 1000m. The distance between 2 points on a MIL-DOT reticle is 3.6 inches at 100 yards, 7.2 inches at 200 yards, etc.


The ultra-thin, hydrophobic surface refinement on ocular and objective lenses protects against all tough environmental influences, is saltwater-repellent and therefore extremely rugged.

NBR Longlife rubber armor

Special rubber armor that is oil, acid and salt water resistant. This armor protects and extends the life of your binoculars at the same time.


Zeroing is the distance to which your scope is adjusted. The trajectory of the projectile (ballistic curve) and the line of sight are set to be congruent at a certain distance. This usually happens at a distance of 100m.

Objective Diameter

This indicates the diameter through which the light passes into the binoculars in millimetres. The larger the objective diameter, the more light can enter and the better the binoculars are suitable for twilight.

Objective Lens

The objective lens of a telescopic sight is also called the entrance lens. The diameter is given in millimetres. It corresponds to the value after the x. E g. a 5-25x56 has an objective lens with 56mm diameter. The diameter of the objective lens determines the amount of light that can reach the eye. With a constant magnification, an increase in the objective lens diameter leads to an enlargement of the exit pupil.

Ocular Lens

The ocular lens is the lens closest to your eye. You look through the eyepiece at the image magnified by the scope. The exit pupil is imaged in front of the eyepiece lens.

Optical Characteristics

Optical characteristics, e.g. 8x30, 7x50 The first number of binocular markings describes how much larger an object appears in binoculars compared to observation without binoculars. You can find out more under magnification. The second number of characteristics, for example 30, indicates the objective diameter in millimetres. For more details, see Objective Diameter.


The parallax is an obvious error between the reticle and the object. This error usually occurs when the eye travels from a blind spot back to the center when looking through the scope.

Porro prisms

The Porro prism system leaves the incident light waves unchanged, which results in a better image quality compared to the roof prism system.

Precision Reticle

The precision reticle is visible throughout the frame and provides measurements in meters or feet (0.33 m). How to measure distances: You sail along the coast and read off the true size of a lighthouse on your nautical chart, which in our example is 40 meters high. The base of the lighthouse is placed at the zero mark on the vertical scale and a value is now read off the scale at the top of the lighthouse. We assume the value 20 here. The distance to be calculated is the actual size, in our example 40m, divided by the read size, in our example 20m, times 1000. 40m / 20 = 2 x 1000 = 2000m. So the lighthouse is 2000m or 2km away. A second example of using the horizontal scale: You have a harbor entrance in front of you that you know is 80 meters wide. Now you place the port side of the port at the left end of the reticle at the zero point and then read a value at the level of the starboard lights. Let's assume the number 60 here. This would result in a value of 1.3. Multiplying this value by 1000 gives a value of 1300 m or 1.3 km. Distance: distance = actual size / read size x 1000. Actual size: actual size = distance x read size / 1000.

Edge sharpness

For physical reasons, the sharpness of the image from the center of the image to the edge decreases. The higher the quality standard of the binoculars, the better the edge sharpness and the lower the waste.

Pipe diameter

The common diameters for telescopic sights are 1 inch, 30mm and 34mm. The larger the pipe diameter, the more stable the system. In addition, the number of "clicks" for height and windage adjustment increases with the tube diameter, which is particularly important for long range shooters. The tube diameter also determines the size of the mounting rings for the scope.

Field of view

The surveyable terrain at a distance of 1000 meters from the observation object. Usually given in meters. When stated in angles, 1°=17.5 m. The field of view is not a criterion for describing the quality of binoculars.

Comfort grip

The ergonomic ComfortGrips are specially shaped, soft thumb pads with a non-slip surface that provide unique handling. The ComfortGrips form a revolutionary symbiosis of high-tech material and the ergonomic requirements of your hands. The innovative thumb pads enable a firm and at the same time comfortable hold. The binoculars are so comfortable in your hand that you will hardly feel them. Even with long-lasting observations, there are no more pressure points.


Impressive visual sharpness — without the hassle of refocusing! Thanks to the Sports-Auto-Focus, you only have to adjust the STEINER eyepieces once to your eyesight and enjoy constant sharpness from around 20 meters. An unsurpassed advantage, which is particularly convincing when the observation distance changes in a flash, in the twilight and in the freezing cold with gloves! With a minimum of moving parts, this technology also results in greater durability and less susceptibility to defects. (single eyepiece setting)

Nitrogen pressure filling

Is pumped into the vacuum of the binoculars via special valves and prevents the lenses from fogging up or the formation of condensation when the temperature fluctuates from -40°C to +80°C. An excellent quality feature that guarantees perfect vision in every situation, e.g. when taking the lens out of the car in the winter cold or from air-conditioned rooms into the heat! The valves also offer the possibility of checking the internal pressure of the binoculars and renewing the nitrogen filling if necessary. Only STEINER binoculars are filled with nitrogen via visible valves!


Remainder of the incident light at the lens, which exits again at the eyepiece after migrating through the binoculars. The more powerful the coating of the binoculars, the higher this light transmission, which shines, for example, with STEINER's top glasses with a first-class value of more than 90%!


Uncoated optical lenses reflect part of the incident light. This results in a loss of light of up to 50% and a reduction in contrast due to scattered light. By coating the lenses (evaporating metal oxides or fluorides) the reflection on the glass surfaces is reduced enormously and the light transmittance is increased. The quality of the coating depends on the number of coated lenses and prisms, the coating technology and the quantity of coating layers. Through intensive research work and constant development studies, STEINER is the leading company for developing and manufacturing coatings and has the world's most modern optics production facility.


The first number in a binocular's model designation, which indicates how much closer the observed object can be seen compared to the human eye.


STEINER-Ferngläser sind durch spezifische Versiegelungstechniken gegen das Eindringen von Feuchtigkeit, Schmutz und Staub resistent. Somit bleibt Ihre Fernglas-Investition gesichert und die hochwertige Optik in jeder Situation optimal geschützt.

Adjustment Turrets

An adjustment turret is one of 2 buttons located in the center of the scope. They are used to adjust the elevation or windage of the reticle position. The subdivision (clicks) are divided into ¼ MOA, 1cm or 1/10 MIL.


For distances further than your scope is zeroed, you must compensate for the bullet drop caused by the ballistic trajectory by lead. Steiner offers you various reticles that show you lead points for defined distances. The prevailing wind speed or movement of the target can also be compensated for by holding it to the side.

Minutes of arc (MOA)

The angular minute is a unit of circular measurement, at 100 yards it is equal to 1.0472 inches. In practice, 1 MOA is given as 1 inch at 100 yards, 2 inches at 200 yards, etc. Elevation and windage adjustment of a scope are usually given in MOA, with one click of adjustment corresponding to ¼ MOA.