Parallax adjustment with a side focus

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Rifle Scopes for Stalking

Rifle Scopes for Mountain Hunting

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Traditionally, rifle scopes had a fixed parallax set at 100 meters or 100 yards; however, with the advance of shooting sports, such an 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 scope 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 sport 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 need no parallax adjustment.

With the ability of parallax adjustment, the accuracy of the riflescope 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 SF – Side focus scopes, parallax is adjusted with a rotation of the turret on 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.

The easiest way to correctly set the parallax is to look at the target and gently rotate the ring on the side focus. 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.

Video presentation of Parallax adjustment on the objective bell

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Hunting riflescopes are the most common type of riflescopes. For this reason, this is the biggest category on our website. Even though there are many types of hunting-riflescopes, there are some characteristics that many of them share.

A rifle with optics - hunting riflescope

Mounting solutions - Ring and Rail mounts

Both ring and rail mounting options are available. This is the only category where rail mounting is available, but it is only available with some middle-class and premium scopes. There are four rail mounting standards altogether (the rail option offered depends on the manufacturer):

LM rail (optical devices with this rail are no longer manufactured but mounts for it are still produced)
Zeiss ZM/VM rail
Swarovski SR rail
Schmidt & Bender Convex rail

Schmidt & Bender Polar T96 2.5-10x50 with a S & B Convex rail

Tube diameter

Tube diameters of 30 mm and 25.4 mm are the most common.

Scopes with a 34mm tube are rare – Schmidt & Bender Polar T96 series is one of the few that use it.
Zeiss Victory V8 and Blaser Infinity are equipped with a 36mm tube,
whilst Swarovski dS is equipped with a tube that measures 40 mm in diameter.

It is important to note that tube diameter does not affect the light transmission rate.

Turrets

Riflescope for hunters is equipped with low-profile, capped elevation and windage turrets. After a scope is zeroed (at 100 m), most users won't make any further adjustments to the windage and elevation. For this reason, the turrets are capped to prevent unwanted rotation.

As such optics is commonly used in forests where one can quickly bump the riflescope somewhere, capped turrets are the best way to avoid the unintentional shifts of the point of impact.
Furthermore, these are among the most delicate parts and can break if hit too hard.
Caps are used to prevent that.
With some modern, premium optics, there is an option of purchasing an uncapped, BDC elevation turret which allows the user to quickly compensate for the bullet drop at longer distances by setting the turret to the number for the corresponding distance (1 – 100 m, 2 – 200 m, 3 – 300 m, etc.)

The reticle

Most riflescopes are equipped with a hunting-oriented reticle. Usually, the reticle is a crosshair with thicker lines at the sides and narrower lines towards the center.

There are no holdovers or hash marks because it is meant to be simple to use.
The reticle is mainly in the second focal plane, meaning that it appears to be of the same size regardless of the magnification, providing minimal coverage of the target.
Blaser Infinity with first focal plane reticle configuration is an exception to the rule.

FFP-hunting optics were used in the past but are gradually dying out. Commonly, the riflescope is equipped with an illuminated central dot, the intensity of which depends on its purpose.

Magnification

The magnification is either

fixed or
variable.

A few decades ago, fixed magnification optical devices were the prevalent type, now it is the other way around. In England, Scotland, South Africa, and some other countries, many users still prefer the fixed type over the variable type. Entry and middle-class riflescopes have a 4–6x zoom factor, whereas the premium ones boast a 6–8x zoom factor.

Parallax

Parallax is typically fixed at 100 m.
If magnification is above 12x, a riflescope is usually equipped with an adjustable parallax setting (side focus).

Swarovski Z8i 2.3-18x56 has an adjustable parallax turret (on the left)

Subcategories

There are many subcategories:

Best Hunting-riflescopes

Riflescopes of the highest quality are produced by the renowned European sport optics manufacturers such as:

Such devices are equipped with:

an illuminated reticle,
commonly a fine, central illuminated dot.

The zoom factor is 6x or greater. There is an option of purchasing an uncapped BDC turret on most. Reticles are in the second focal plane, except with the Blaser Infinity series which features an FFP-configuration.

Premium optics boast:

an exceptional field of view,
impressive resolution,
a high light transmission rate, and
a high degree of colour fidelity.

They are difficult to compare because there are only small differences among them, but each series has its own strong point (Leica Magnus series, for example, is known for its incredibly wide field of view).

The middle-class devices are not to be overlooked since its popularity has risen considerably in the last few years.
Most of these devices are made in Japan and highly popular because of their excellent price to performance ratio.
Some European-made devices can also be found in this class.

A short presentation is available here.

Short Presentation | HuntingRiflescopes | Optics Trade from Optics-Trade

Parallax adjustment with a side focus

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