- Nagyítás (magnification)
A változó nagyítású optikai termékek sokoldalúbbak, mivel szélesebb körű nagyítással és nagyobb látószöggel vannak megtervezve. A távcsőben lévő nagy számú lencsék miatt, a változtatható nagyítású optikák nagyobbak, nehezebbek és alacsonyabb fényáteresztő képességgel bírnak. A változtatható nagyítás ritkán van jelen a távcsövekben, leginkább a puskákra szerelhető céltávcsövekben, illetve “spotter” távcsövekben használatos. A változtatható nagyítás ezen esetekben több előnnyel jár, mint hátránnyal. A magas minőségű, változtatható nagyítású céltávcső nagyon ritka. - Objektív lencse átmérő (objectiv lens diameter)
A termék nevének/megnevezésének második értéke utal az objektív lencse lencse átmérőjére. Például egy 10×42 távcsőnek, 42 mm átmérőjű optikai lencse van az elején (a távcső azon vége, mely közelebb van a látott objektumhoz). Ismeretes, hogy minél nagyobb az objektív, annál több fény jut át rajta és a kép amit látunk, annál világosabb lesz. Mindez azonban egy bizonyos optikai termék nagyításától és minőségétől függ. Bár a távcső nagyobb objektívátmérője jobb képet eredményez, a méret növeli a súlyt, így az nehéz és nehezebben kezelhető lesz. A puskákra szerelhető céltávcsövek esetében a nagyobb objektív lencse méret, további szerelési problémákat jelent.
A legáltalánosabb objektív lencse átmérők 24 mm, 42 mm, 50 mm és 56 mm.
- Látómező (field of view)
Maximal Field of view is the range of your visual area, for rifle scopes its measured at 100m. For example if maximal field of view is 13m/100m, means that you have on 100m a maximal view of 13m. Rifle scopes with Variable magnification (click for the info in specifications), maximal field of view is meant when using lowest magnification setting. The higher the magnification the smaller the field of view.
Field of view is important feature when choosing a rifle scope for you activity. Larger field of view will give you wider view/image, which is important factor when you are aiming or hunting moving targets. Opposite, smaller field of view gives you narrower view/image, this option is more suitable for non moving/static targets. Better quality rifle scopes have larger maximal field of view.
Just for information, parameter of lens diameter doesn`t give you a info about field of view. Lens diameter has influence only on the brightness. For example, you can have 2 rifle scopes that have for example lens diameter of 56 mm, but they can have different maximal field of view.
- Exit pupil
The concept of pupil is fundamental for the observer, even to determine which is the most suitable equipment or accessory. A well-known parameter for binocular users is precisely the exit pupil, which would be the effective area at the exit of the ocular where the image captured by the observer’s pupil is formed.
It is the beam of light that leaves the ocular and enters the pupil of the human eye. The exit pupil must not exceed 7 mm at any time. The reason behind is that human eye cannot expand over 7 mm. With age, the maximum opening of the pupil decreases, so that a person of 60 years will reach a maximum opening of 4 or 5 mm. For this reason, it is necessary to calculate for each observer and according to their age, the minimum expansion factor to be used.
The more an eyepiece is able to magnify the image (and the smaller its focal length), the smaller the size of the exit pupil will be. For example: In a 200/1000 mm telescope and a 35.7 mm eyepiece, an exit pupil of about 7 mm will be reached. With a 10 mm eyepiece, the value will be only 2 mm.
We recommend optical devices with the exit pupil bigger than 5 mm for the low light use. Ideally, such scopes or binoculars should have around 7 mm exit pupil. For daytime use, exit pupil can be between 3-5 mm and even with unique products at least 2 mm exit pupil is advised. Use of the products with an exit pupil smaller than 2 mm is very uncomfortable and tiring.
- Eye relief
Minimal eye relief is a minimum distance between the eye and eye-piece lens (rear of the scope, some manufactures call the eye piece ocular). For safety reasons, due to the recoil of rifle, minimum eye relief for rifle scopes has to be at least 80mm. Larger rifle calibers produce higher recoil, so it is adviced to have a minimal eye relief of 90mm or even more. Due to safety reasons new rifle scopes have longer eyerelief than older. Longer eye-reliefs were achieved with an advance of optical tehnology.
Because of safety reason some rifle scopes for safari rifles have extended eye-relief of more than 120mm. Scout and pistol scopes more than 500mm eye-relief, since they are usually mounted far away from the user.
Safety should be always on 1. place when handling guns and shooters often ignore, so make sure that you don`t get a »black eye« injury and choose the scope with a minimal eye relief of at least 90mm.
Cső átmérő (main tube)- Szállemez elhelyezkedés (reticle focal plane)
- Szállemez megvilágítás (reticle illumination)
Reticle illumination is the possibility to illuminate the rifle scope reticle with light. Some rifle scopes use reticle with illumination possibilities. There are two main types of reticle illumination on the market:
– illuminated point in the middle of the reticle,
– illumination option to light up the whole reticle.
For hunting, the reticle with central light point (dot) is more recommended. Rifle scopes that use illumination of the whole reticle are more recommended for tactical and sports use. The power of illumination light can be either day strong or visible only in the lowest light situations (in dark). For the driven hunts, IPSC or tactical CQB daytime strong illumination is more usable. Illumination option only visible in low light conditions is better for hunting in low light conditions or even in the dark. Rifle scopes that use as many different intensity levels as possible are better because they offer more possibilities to find a perfect view of the reticle in different lighting conditions.
The most advanced rifle scopes use optical fibers built in the middle of the reticle as a light dot. In high quality rifle scopes, these illuminated dots are of the smallest size. For example, if the illumination is set to OFF, you don`t see this illuminated dot at all and when you turn the illumination ON, the light dot is visible. High quality rifle scopes enable the user to fine tune illumination intensity. This way the reticle is always illuminated just right in accordance with the ambient light condition. Very dim in low light and extremely bright in the daytime. Newer rifle scopes have built in automatic turn off electronics that turns off illumination of the reticle when you don’t use your rifle scope for some time the illumination of reticle goes automatically to OFF. Such scopes have built in motion sensor to determine when the scope is not in use. This preserves battery life.
Reticle illumination option provides you a better accuracy at night and in low light situations. With non-illuminated reticles, you could have problems in low light situations, when you can see the target but not the reticle. The type of illumination for low light usage only is mostly meant for raised hide hunting.
Daytime bright illumination is the best option for driven hunting, IPSC and tactical shooting.
- Parallax compensation
Traditionally, rifle scopes had a fixed parallax set at 100 meters or 100 yards; however, with the advance of shooting sports, such approach was not adequate anymore. Scopes with fixed parallax offered the best resolution only at one distance (100 meters/yards) at which the target was in focus. At all other distances, the picture was less sharp or even blurry. An even bigger problem with this type of scopes was the fact that, when shooting at the target, not at the same distance as the scope parallax setting, the shooter had to be very careful about his eye alignment with the optical axis. If the eye is moved away from the optical axis, the reticle on the target will move, which will worsen the accuracy. Since these errors are small, the fixed parallax option is still considered accurate enough for traditional hunting. For sports shooting, though, such small error leads to poor results. Parallax errors become more pronounced with magnifications higher than 12x, and that means the majority of scopes with magnification range under this value needs no parallax adjustment.
With the ability of parallax adjustment, the accuracy of the rifle scope is greatly enhanced at all distances. The shooter, however, has to adjust the parallax setting before making the first shot. Such scopes usually have AO – Adjustable Objective or SF – Side focus acronym in their name.
With AO – Adjustable Objective scopes parallax is adjusted with a rotation of the ring on the objective bell; adjusting the parallax this way can hardly be done when in a prone position and is not the best solution for situations when parallax must be adjusted often. Due to this reason, such scopes are usually used for benchrest competitions and similar, where parallax is adjusted only initially.
With SF – Side focus scopes, parallax is adjusted with a rotation of the turret on the left side of the main tube. Such an approach offers easy adjustment of the parallax in the prone position and is the best solution for situations when parallax must be adjusted often. Due to this reason, such scopes are usually used on tactical scopes and similar, where parallax is adjusted before each shot and distances to the targets change rapidly. Scopes, which offer parallax adjustment with a side focus, are usually bigger and heavier than counterparts with parallax adjustment on Adjustable Objective. They are also more expensive to produce. Due to the size of the internal mechanism for side focus adjustment, the majority of such scopes have a tube diameter of 30mm or more.
Scopes, which offer parallax adjustment on objective bell, are usually smaller and lighter than counterparts with parallax adjustment on the side focus. They are also cheaper to make and offer adjustment that is more precise. Due to the size of internal mechanism for side focus adjustment, the majority of scopes with a tube diameter of 1 inch have an adjustable objective and not the side focus.
The easiest way to correctly set the parallax is to look at the target and gently rotate the ring on the objective. When the target is in focus and the image offers the best sharpness, move the eye from the optical axis to any direction. If the rifle is properly supported and fixed, the reticle should not move on the target when the eye is moved from the optical axis. If it does, parallax adjustment must be fine-tuned until the reticle is still, even if the eye of the shooter is moving around the optical axis.
Do not mind the meters or yards written on the adjustable objective, since they only provide an approximate value. There is nothing unusual if these values do not correspond well with the actual target distances.
- Bullet drop compensation (BDC)