Focuhunter manufactures a variety of rifle scopes in different sizes, most of which are custom-made from CNC aluminum. Typically, rifle scopes consist of various components, including lenses, CNC-machined metal parts, some plastic elements, and occasionally copper parts, like the latest Falcon series, where the adjustment screws are copper for added adjust precision.
Today, we’re discussing the primary components of a rifle scope visible from the inside. The key elements of a rifle scope include its lenses, specifically the objective lens assembly, erector lens , magnifying lens and eyepiece/ocular lens.
Focuhunter Parts of a rifle scope.
1.Objective Lens Assembly
The objective forms an inverted image at the first focal plane (FFP). The objective and eyepiece together form an “afocal” telescope that produces a focused image at infinity. The erector lens forms a focal telescope that adds additional magnification, creates an erect image at the second focal plane (SFP), and provides crosshair adjustments (both windage and elevation).
The objective lens assembly constitutes the foremost component of a riflescope, positioned at the end nearest to the target. Its primary function is to gather light and transmit it through the scope to create a clear image. The diameter of the objective lens, measured in millimeters, is a critical determinant of light-gathering capability; larger lenses allow for greater light intake, thereby improving visibility in low-light conditions. Moreover, the objective lens is crucial in determining the field of view, with larger lenses providing a wider vista, thus facilitating target acquisition. Most hunters prefer a lower magnification lens power and a larger objective lens because they give a brighter image of the target.
You can determine the objective lens size from the riflescope model number. For instance, in a 1-6×24 Riflescope, the objective lens has a diameter of 24mm.
Hunting Scope 1-6X24-102-M (4)
2.Erector Tube Assembly
The erector tube functions to “erect” the image, which is responsible for inverting the image transmitted by the objective lens. In the absence of this assembly, the image viewed through the scope would be upside down and reversed.
The erector tube assembly includes the magnifier and reticle. A spring-loaded tab system presses the riser tube against the windage and elevation screws. As the adjustment screws turn inward into the scope tube, they push the riser tube against the spring system. As you adjust the windage and elevation knobs, it moves in tiny increments.
The windage and elevation adjustments reposition the FFP reticle by tilting the tube that contains the erector lenses (refer to Figure Focuhunter Parts of a rifle scope). This erector tube magnifies both the FFP reticle and the scene’s objects. the SFP reticle is a constant size, regardless of erector tube magnification.
Focuhunter Rifle scope optical design
Windage and Elevation
Windage refers to the horizontal adjustments made to the firearm’s sights, while elevation refers to the vertical adjustments.
Adjustments on a riflescope are typically made by turning or “dialing” a turret, which are the knobs located on the top and side of the scope. Each turn of the turret produces an audible and tactile click, signaling an adjustment, For example, the adjustment value is usually 1/2 MOA, 0.25 MOA, and the value is different for each type of scope. These clicks alter the angle at which the internal components of the scope reflect light. This change in angle causes the reticle to move up or down, allowing the shooter to fine-tune the point of impact.
Magnification Lenses
Rifle scope magnification enables the shooter to see and identify target features from long distances.
The Erector Tube Assembly is responsible for magnifying the image in a scope. When adjusting the power ring on a variable power scope, the magnifying lenses inside the erector tube shift to change the magnification level. Typically consisting of two lenses, the system operates by moving these lenses back and forth in synchronization along a track within an inner, secondary tube. As magnification increases, the field of view decreases.
Increasing magnification causes the lens to move closer to the objective lens while decreasing magnification brings the lens closer to the ocular lens.
3.Eyepiece/ocular lens
Focuhunter Exit-pupil-Eye-relief
The eyepiece holds the ocular lens.
After passing through the erector system and the reticle plane, light travels through two additional lenses, which enable the shooter to focus both the image and the reticle to their eye. The final lens in this path, closest to the eye, is the ocular lens, housed in the eyepiece. This lens receives the light and transmits it to the eye.
The eyepiece may also be adjustable, typically featuring a diopter, allowing for a sharp focus on the reticle. This adjustment should be made once when initially setting up the scope, as it is specific to each individual’s eyesight
The ocular lens is designed to have an “exit pupil” , it is usually referred to as “forgiving” or “unforgiving”, the distance of the exit pupil focal point from the ocular lens is based on the weapon it is mounted to.
Exit Pupil = Objective Diameter / Magnification
Human eyes can generally only utilize an exit pupil up to about 5 millimeters (mm). The exit pupil refers to the diameter of the light image seen through the eyepiece. For daytime use, an exit pupil of 2 to 3 mm is sufficient, but in lower light conditions, a scope with a 5 to 7 mm exit pupil is necessary.
Eye Relief
Eye relief refers to the distance between your eye and the ocular lens of a scope, allowing you to see the full field of view. This is a key design specification in scopes. Typically, eye relief ranges from 3 to 4 inches, roughly equivalent to 10 cm, depending on the magnification setting. For high-recoiling rifles, a minimum eye relief of 3.5 inches is recommended. When using a riflescope, you should adjust the eye relief according to the operation guide and personal experience. In general, scopes with longer eye relief are preferable.
CNC machines.
Focuhunter is a manufacturer of optical Products. We have rich experience in the manufacturing of different shooting optics, including the Riflescope, Red dot Sight, Prism scope, Magnifiers, Scope Rings and Rails, Scope Accessories, etc. Please feel free to Email Us for more details.