Optics Archives

Reticules for Africa

Aug 5, 2013 | Optics

By Pierre van der Walt

	Crosshair Reticule
	Advantages: The fine lines do not obscure small targets at range and it therefore is a suitable for long-range application on small animals and varmints. Quite acceptable for African plains game hunting during daytime
	Disadvantages: The fine lines are difficult to see in poor light or against dark backgrounds. It is a bright light only option for good eyes and slow shooting.


	Dot Reticule
	Advantages: The dot provides an uncluttered image of the target and provides a very natural point for the eye to use as reference point. It mostly provides a bit faster target acquisition than the stand-alone Crosshair. Not popular in Africa.
	Disadvantages: It provides a single reference point, and if that is not visible in poor light or on dark target, then the hunter has no other means of aiming. That can be circumvented by opting for an illuminated dot. If the dot is large it limits the riflescope’s application to closer ranges or larger species.


	Target Dot Reticule
	Advantages: It employs the strengths of both the Dot and the Crosshair designs and provides a natural reference point that can be used under a wider range of conditions and backgrounds than the stand-alone Dot. It is a bit more visible than the stand-alone Crosshair, especially when illuminated. It is an excellent choice for shooting at round targets as in target shooting. It is fine for African plains game hunting across bush and medium ranges
	Disadvantages: It provides a single reference point, and if that is not visible in poor light or on dark target, then the hunter has no other means of aiming. That can be circumvented by opting for an illuminated dot. If the dot is large it limits the riflescope’s application to closer ranges or larger species.



	Circle Dot Reticule
	Advantages: The circle dot provides a large, readily visible target-encircling reference point that is very quick to acquire with a finer aiming dot providing precision if needed. It is very suitable for the hunting of moving targets at close range and is fine for thick-skinned African game, especially with illuminated capability.
	Disadvantages: It does obscure more of the target and, unless illuminated, it is not much better than the normal Dot design for normal hunting


	Duplex Reticule
	Advantages: Justifiably the most popular reticule in the New World and probably the most sensible general hunting reticule, the Duplex offers the fine central aiming point in combination with bolder sections that remain visible under most daylight hunting conditions. It also offers the tips as reference points for windage and elevation.
	Disadvantages. The fine section of the reticule can still be ‘lost’ in some light and the bold sections obscure some target. This is resolved by using illuminated centre sections or the addition of a dot, black or illuminated.


	CPC Reticule
	Advantages: It offers the advantages of the Duplex, with the additional benefit of tapered posts which are less intrusive of the sight picture. It is an excellent design for normal hunting in Africa across all ranges. Companies such as Schmidt & Bender offer a variety of German reticules options with CPC-style tapered posts.
	Disadvantages. It is useable in more light conditions than the normal Crosshair, but not as versatile as the Duplex. It also does not offer any alternative aiming points to the hunter.


	German #4 Reticule
	Advantages: The bold posts are visible in almost any light conditions, and the absence of a heavy post above the aiming point provides a fairly good image of the target. When placed in the first focal plane of the riflescope, as often is the case with European riflescopes, the reticule size will appear to change with magnification.
	Disadvantages: The fine aiming section of the reticule is very narrow and a lot of the target is obscured by the heavy posts. It is not a fast reticule to use with precision. There is a shorter post version known as the German #7


	CD Reticule (German #9)
	Advantages: A very fast and intuitive system combining the German #7 reticule with the Circle Dot. It is an excellent African dangerous-game reticule, and in illuminated configuration it does not disappear on the dark skin of pachyderms. It essentially is a short-range system.
	Disadvantages: It is not suitable for long-range hunting or small game. As with all illuminated reticules, one has to be constantly aware of the state of the battery and carry extras, but battery life has improved dramatically over last few years.



	German Post (German #2)
	Advantages: An excellent African reticule, especially on dangerous game, as it is bold enough to work in almost any light. It offers a very simple and uncluttered sight picture and can also be had configured with an illuminated arrow tip for fine aiming.
	Disadvantages: It obscures the body of small targets at range. The flat top is not as precise as a sharp tip or fine line, but it primarily is a large-game, short-range reticule.


	German #1
	Advantages: A bold reticule that works well in poor light and jungle conditions, especially when the post tip is illuminated. It provides the hunter with better vertical referencing than the German #2 post. It is a fine large- and dangerous-game system for short-range use.
	Disadvantages: The sharp tip can be lost in some light conditions and it also obscures small targets at range.


	German #56
	Advantages: This reticule has no notable advantage unless the dot is illuminated, in which case it offers a natural and easy to acquire reference point for short and medium ranges.
	Disadvantages: It does not offer the fine aiming reference of a crosshair or post with tip at perceived point of impact. If the dot is ‘lost’ on a dark target the hunter is in trouble as he will have to guess point of impact.


	Trajectory Compensating Reticule (Customized)
	Advantages: Some companies such as Leupold offer hunters reticules with alternative elevation aiming points customized to the exact bullet and velocity combination used. This offer an uncluttered sight picture, very little guesswork, as it is only affected by atmospheric variation which is not that much across hunting ranges. Generally based on the Wide Duplex reticule, this most likely is the ultimate African hunting reticule. These reticules are best combined with a laser rangefinder for exact measurements.
	Disadvantages: The reticule is bullet- and velocity-specific, and the riflescope is forever tied to a single load that may become unavailable in time, and animals do not always stand at precisely calibrated ranges. It is also costly and time-consuming to send the riflescope to the manufacturer for the retrofit. The Ballistic Turret system is most probably a better option.


	Trajectory Compensating Reticule (General)
	Advantages: These reticules enable the hunter to predetermine reticule reference points for bullet drop at different ranges. They are fast to use provided range is known. Some, such as the Swarovski TDS (not pictured), also provide range-finding capability based on fitting the animal chest or whither height between lines and calculating the range. Having the alternative bullet-drop aiming points reduces the amount of guesswork the hunter has to engage in, and also the degree to which he has to compensate for wind or elevation
	Disadvantages: Again these reticules, depending on actual design, do not always work that well in poor light. The SA Hunter depicted reticule is one of the better designs, from both visibility and simplicity perspectives.


	Range-finding Reticule (Mil-Dot)
	Advantages: The Mil-Dot enables the hunter to scale the target of known size in relation to the Mil-Dots and use the result to calculate the range to the target. The reticule itself offers enough reference points to compensate accurately from the fall of a missed shot for a precise second shot.
	Disadvantages: The system requires some experience in the correct and accurate placement of the reticule on the target for the Mil-Dot reading, and is further dependent on the correct assumption of target size. It is a slow system that requires time to read and make calculations for which a calculator or reference sheet is required. It is easy to get confused by all the dots. Some designs alternate dots and bars and that improves the concept from a hunting perspective.


	Range-Finding Reticule (Animal-Scaling)
	Advantages: Hunting-dedicated reticules employ a system whereby animals are fitted between scaling lines and the range then calculated by a variety of means. It enables the hunter to make a highly informed range estimation and offers windage referencing to various degrees. These reticules, such as on the Horus Vision versions can become very complicated and extremely cluttered. The South African Lynx RF reticule depicted works very well on African plains game.
	Disadvantages: It takes a bit of time to fit the target between the correct lines and make calculations. Sometimes grass and other objects affect the ability to place the correct animal parts between the lines and that affects the accuracy of results. Depending on the complexity of the actual design, hunters have to engage in the effort to really familiarize themselves with the system. These reticules often are difficult to use in poor light.

Zero Riflescope with One Shot

Aug 5, 2013 | Optics

By Pierre van der Walt

Yes, it can be done! Assuming you have fired a fouling shot and you shoot straight.

Step 1	Set Target Up
	Set a target up at the intended zero range, i.e. 100 yards. For this method a round aiming point works best. The full aiming point must be visible through the barrel, so it must not be too large or too small. The closer the aiming point is in size to what you can see through the barrel, the more accurate the result is

Step 2	Set Rifle Up
	Remove the rifle’s bolt and place it on bags with which you can pack it down firmly. Equipment that works well for this purpose are: Bullsbag X7 Modular System Caldwell Lead Sled

Step 3	Aim through Barrel
	Centre, and by centre we really mean *centre*, the target in the barrel and make the rifle immovable. Then adjust the riflescope reticule to centre on the target.

Step 4	Fire the Shot
	Fire the shot without moving the rifle. Remove the bolt without moving the rifle or the rest/bag and adjust the rifle to regain the exact above correct sight picture through the barrel and riflescope. The ideal would be if no correction has to be made to the rifle, but recoil makes that virtually impossible. Make sure the rifle is packed tight once this is achieved.

Step 5	Adjust Reticules
	Now peek through the riflescope without moving anything and find the bullet impact point on the target. Unless you are very lucky the bullet hole will be some distance from the aiming point and reticule position. Without moving the rifle or the rest/bag, adjust the reticules to centre on the bullet hole.

Your rifle and scope are zeroed! You can verify it with a second shot.

Determining the Correct Group Center

Aug 5, 2013 | Optics

By Pierre van der Walt

While one can often get away with a rough estimate of the actual center of a fired group on a target and adjust accordingly relying somewhat on trial-and-error, there are instances such as open sight adjustment, when the exact statistically correct center of the group has to be determined. That center of the group is not in the middle of the bullet holes the furthest apart horizontally and vertically.

When you really need to be accurate you obviously have to start with a fouling shot not aimed at the target reference. Once the barrel has been fouled, you then fire your group, but it has to consist of at least 5 shots for moderate statistical validity. A 3-shot group is useless for this purpose. Once the group has been fired you draw a vertical line (AA in our example) through the left-most bullet hole if the group is on the left of the target, or through the right-most bullet hole if the group is to the right of the aiming point. Also draw a horizontal line through the bottom bullet hole if the group is above the aiming point, or through the top hole if it is below the aiming point. (BB in our example.)

Determining Horizontal Center

Step 1	Total the Deviations from the AA Reference Line
	Shot 1	=	0.000”	(0,00mm)
	Shot 2	=	1.044”	(26,5mm)
	Shot 3	=	1.119”	(28,4mm)
	Shot 4	=	0.747”	(18,8mm)
	Shot 5	=	1.284”	(32,6mm)
	TOTAL	=	4.194”	(106,3mm)

Step 2	Divide the Total for an Average Deviation
	4.194”	÷	5 shots	= 0.8388”
	106,3mm	÷	5 shots	= 21,36mm

Step 3	Mark the Center Line
	Draw a Vertical Line XH 0.8388” to the right of line AA. That constitutes the statistical horizontal group center.

Step 4	Measure Correction
	Measure distance between XH and the aiming point to determine correction required. In our example it is 0.863” (21,9mm) indicated by the horizontal green arrow.

Determining Vertical Center

Step 5	Total the Deviations from the BB Reference Line
	Shot 1	=	0.836”	( 21,2mm)
	Shot 2	=	1.867”	( 47,4mm)
	Shot 3	=	0.000”	( 00,0mm)
	Shot 4	=	1.492”	( 37,9mm)
	Shot 5	=	1.192”	(30,3mm)
	TOTAL	=	5,387”	(136,8mm)

Step 6	Divide the Total for an Average Deviation
	5.387”	÷	5 shots	= 1.0774”
	136,8mm	÷	5 shots	= 27,4mm

Step 7	Mark the Center Line
	Draw a Horizontal Line XV1.0774” above line BB. That constitutes the statistical vertical group center

Step 8	Measure Correction
	Measure distance between XV and the aiming point to determine downward correction required. In our example it is 1.5934” (40,5mm) indicated by the vertical green arrow.

Answer	X Marks the Spot
	The intersection point (X) is the actual center of this group. One can now adjust very precisely and save on ammo and time.

This method is particularly important when intending to drift open sights. The formula for open sight drifting is provided in the article: Open Sight Adjustment & Formula.

The History of Riflescopes

Aug 5, 2013 | Optics

By Pierre van der Walt

The Arabs pioneered the development of the telescope and had already manufactured telescopes in the eleventh century. This knowledge was lost somehow during the Middle Ages, probably due to the Crusades.

A Dutchman, Zacharias Janssen (1588 – 1630) rediscovered the knowledge during the 16thcentury.The news spread across Europe and by 1609 commenced building telescopes in earnest. By using a concave as well as a concave lens Galilei succeeded in viewing Jupiter’s moons. The lens combination furnishes an upright image and the system has since become known as the Galilian system.The German scientist Johannes Kepler (1571 – 1630) used convex lenses in both the objective and ocular positions. This provided a much larger field of view than the Galilian system, but the image with the Kepler system is not only inverted but hind part foremost as well.

Telescopes were installed on rifles for sighting purposes during the 17thcentury. The first reference to scopes on rifles is found in Francesco Lana de Terzi’s (1631 – 1687) Magister Naturae et Artis of 1684. King Frederick the Great of Prussia noted in 1737 that he had fired a telescoped rifle. Riflescopes naturally were very expensive and, therefore, gained little commercial acceptance for centuries. It was more popular (especially on sniping rifles) in Europe than anywhere else in the world, mainly because the necessary know-how was centered in Europe at the time.

The breakthrough came when the American, William “Bill” Ralph Weaver (1905 – 1975) succeeded during the early 1930s to manufacture and market rifle telescopes at an affordable price. Bill Weaver had no formal optical training and taught himself the technical aspects of riflescopes. He first manufactured a riflescope in 1931 and founded the W.R. Weaver Company at El Paso Texas during 1933 to manufacture affordable riflescopes. Weaver’s first riflescopes were not manufactured in Texas but in Newport, Kentucky, and were substantially smaller, lighter and much cheaper than their European counterparts, and became an immediate success.

Weaver experienced several serious problems. Virtually no gunsmith knew how to mount a riflescope onto a rifle. Production rifles of the period were not equipped with holes drilled and tapped for riflescope installation. Weaver had to mount all the riflescopes he had sold himself and soon realized that it was impossible. To overcome the problem he toured America training gunsmiths. As time progressed gunsmiths gradually took the burden off his shoulders, allowing him time to lavish his attentions on his primary enterprise. Rifle manufacturers also started drilling and tapping their rifles for riflescope mounting. Today we take these things for granted and mandatory, and it is hard to imagine a time when it had not been the case.

Weaver not only succeeded in making the riflescope available and affordable to the average man, but he initiated a brand-new industry and, in the process, selling more riflescopes by the time he died than any other rifle manufacturer in the history. The company fell on hard times and Weaver was forced to sell it in 1968. This process repeated itself for a number of years until it was sold to the ATK Sporting group that also owns Federal Premium, Alliant Powder, RCBS, CCI, Fusion, Speer Ammo, Speer Bullets, Estate Cartridge and Blazer.

Another factor that troubled Weaver was the shape of the bolt handles of the rifles available at the time. The shape prevented bolt manipulation once a riflescope had been installed, as most protruded rather sharply from the bolt shaft. He solved the problem by either mounting the riflescope far enough ahead of the bolt handle’s path to allow the handle to pass behind the ocular bell, or he altered the bolt so that it could pass underneath the riflescope. The latter option became the more popular and nowadays virtually all manufacturers design their rifles to allow normal operation, even with a riflescope in place.

Adjusting riflescopes was a problem in itself. Most riflescopes were internally adjustable for elevation only. Adjustments were not calibrated and no pre-determined adjustments were provided on the early riflescopes. Windage could only be adjusted externally. In other words, the vertical crosshair could not be adjusted. The entire riflescope had to be moved sideways at the rear mount and this caused problems. The riflescope was firmly clamped in the front ring and any lateral adjustment of the rear part of the riflescope bent the riflescope. Bending it, placed the tube as well as the lenses and seals under stress,often resulting in breakages. Apart from that, it had a detrimental effect on the path which the light rays followed through the riflescope.

Mounting holes were seldom perfectly aligned, resulting is slightly askew base positions. Manufacturing tolerances resulted in variances in the height differences between receiver and bridge. Reticules in the early riflescopes were only in the rarest of cases exactly centered in the riflescope image. Shims were used to offset such errors and to move the reticules nearer to the centers of the image seen through a riflescope. In due course the permanently centered reticule made its debut. This development compensates for slight installation errors whilst keeping the reticule intersection in the exact centre of the field of view. It would be an understatement to say that permanently centered reticules was one of the most important and welcome steps in the development of the riflescope.

At the outbreak of the Second World War American riflescopes had become adjustable on both planes. This was not the case with European riflescopes, though. Today we are fortunate in that apart from having riflescopes which are internally adjustable on both planes, we also have adjustable mounts which allow lateral movement of the riflescope’s rear without warping it. Minute and extremely accurate adjustments are, therefore, possible nowadays.