Hunting Scope Selection Considerations

By Scott Fletcher

PH: “Can you see it?” Extended silence. PH: “Can you see it”?! Hunter: “HELL NO”!!!!!!

The dialogue above reflects a personal “Groundhog Day” nightmare that has occurred on every trophy hunting trip to South Africa. I am primarily guilty, as identifying any animal through thick brush, let alone the one selected by my PH, is embarrassingly difficult. In an uncommon fit of exasperation, Koos DeMeyer, a trusted friend and PH, once curtly instructed: “Scott! Look through the brush, not at it!” Right….

My inability to see the animals through thick brush using a scope had nothing to do with its specifications and features. To the contrary, the scope selection process discussed in this article indicates the scope used had specifications and features that were essentially ideal for the hunting conditions encountered. Full Disclosure: that scope’s selection had just been dumb luck, the stuff of a blind hog finding acorns.

Several recent management hunts using two inappropriate scopes have painfully identified other issues that should have been resolved by my number-crunching inclinations prior to those hunts. I had selected scopes primarily applicable for long-range target shooting because of their degree of magnification and the expected shot distances. The specifications of the selected scopes limited timely identification of a specific animal in the herd at the magnification I had expected would be required for positively targeting the heart.

A recovered animal results from a successful vision process that can be either facilitated or impeded by the scope. On a safari, a PH identifies a specific animal. The hunter must then expeditiously identify the specific animal in the rifle scope. Not only must the rifle scope facilitate initially identifying this animal, it must subsequently provide magnification and focus compatible with the targeted vital organ(s) within a time frame that enables a shot before the opportunity is lost. The process can be defined/quantified as target acquisition time (TAT). Seconds can (and do) matter.

North American hunters that shoot from a blind or snipe at a distance well beyond each animal species’ “safe space” are typically not faced with the urgency suggested by the dialogue and my overview. Target assessment and acquisition is typically far more casual. These hunting scenarios can potentially reduce the necessity for strict movement and noise discipline. When hunting from a blind or at extended distance using a laser rangefinder, the hunter knows the shot distances.  At known shot distances, scope focus and magnification adjustments can occur before target acquisition rather than after. These hunting methods can allow the opportunity for unrestricted line-of-sight between the hunter and the animal. Shooting from a blind or hide allows strategic trimming/removal of vegetation to occur. Any resultant open areas can also provide improved illumination of the animal. Finally, hunting over bait or a water source can potentially retard/reduce the otherwise frenetic activity associated with herd dynamics.

These hunting conditions can be in stark contrast to a traditional stalked trophy hunt scenario in Africa. Dense vegetation can both obscure the animal and mask it in strong shadow. Traversing through such vegetation presents almost infinite opportunities for breaches in noise discipline. Both an individual animal and the herd’s collective “triple threat” detection system of scent, sight, and sound (S3) may detect the hunting party before it detects them. The complexity of the hunting scenario can be magnified by the requirement of shooting only a specific animal in a herd where both sexes can have horns or not, e.g. zebras. In Africa, bachelor herds of bulls can be more common than lone bulls, again requiring target acquisition of “the” bull.

The shooting position on a stalked hunt is typically off of sticks. This position is essentially an improved “offhand” that may have to occur “in the open” to enable a shot, thus potentially exposing the hunter and the PH. This exposure only enhances the odds of being “busted” because of the required placement movement and any movement by the hunter in panning the rifle to find “the” animal, then make any required focus or magnification adjustments.

Finally, the hunter in a stalk scenario tends to be the “tail-end Charlie”, following a conga line of at least the PH, but possibly including the tracker on point. Such positioning limits/obscures direct, forward observation of the intended animal. The field craft of both the tracker and PH enables them to easily identify where “the” animal is; a hunter may not. Invariably, I seldom do. After the PH places the sticks, TAT can increase because of the time needed to literally find the specific animal, then focus and potentially adjust the scope’s magnification to enable the shot.

Photo 1 is an example of moderate-to-thick vegetation that can be typically encountered in the Limpopo province of South Africa. Note that there are no leaves, making observations “easy” (for native South Africans). Photo 2 and Photo 3 identify approximately the same vegetation density as Photo 1. Can you find the animals in Photo 2 and Photo 3?

In his book African Rifles and Cartridges, John Taylor repeatedly talks about hunting elephants “in the thick stuff”. Photo 4 presents a good visual, as well as the answer to the question “Just how thick is thick vegetation?”

In terms of clearly identifying animals through the brush, the Hunting Gods have dispensed leniency in Photo 5, gifts in Photo 6, Photo 7, and Photo 8, and a legitimate miracle in Photo 9. Note in all photos that the animal is looking directly at the camera. Photo 10 represents a squandered miracle that the Hunting Gods have noted and have found offensive to the point of sacrilege. Envision the kudu engaging “launch mode” after the Great White Blunder alarmed it with his rapid arm movement on the scope to get “the” focus and magnification. A stout measure of penance/retribution is inevitable and is sure to be dispensed sometime during the remainder of the safari.

Distance can affect quick identification of animals almost as well as vegetation. Can you spot the lone zebra and herd of (presumably) impala without magnifying the image in Photo 11? The reason I say presumably is I did not know the herd was there when I took the photo of the zebra. Although I had not noticed them, it is obvious in the photo that herd members had noticed me.

Photos 2 through 11 all identify the urgency of TAT: I had been noticed and was “on the clock”. The time available is related to each species’ “safe space” that can vary based on hunting pressure. As long as the hunter is outside of the safe-space yardage limit, the animal may take sufficient time to assess/process the visual alert to allow a shot as long as the magnitude and speed of any associated movement are subdued. If the hunter is within the space-space yardage limit, any detected movement typically results in an almost instantaneous engagement of “launch mode”. Finally, hunting pressure can be so intense that there is no safe-space distance. No matter what the distance, the herd or animal flees immediately after identifying a vehicle or any individual of the hunting party.

The rifle scope, with its attendant specifications and features, either facilitates or detracts from TAT between stick setup and trigger squeeze. The following narratives identify these features and present discussions of how specifications for each can potentially either reduce or increase TAT.

Scope Magnification

The most obvious scope feature is its ability to effectively magnify the target. “Effective” magnification means the target is sufficiently large enough and the presented viewing width (field of view or sight picture) is wide enough to identify both the animal and any nearby reference features. Such reference features can be a bush, a clump of brush, a tree, or an adjacent animal that is obviously “different”, such as one facing directly at the hunter. In an ideal world, the initial magnification is also sufficient to precisely locate the desired bullet impact point (e.g. lungs, heart, etc) on the animal. Time to adjust the magnification to initially find “the” animal, then readjust the magnification to clearly identify the actual aim point obviously increases TAT.

With any scope, increasing the magnification reduces its field of view (subsequently discussed in detail) and reduces the available illumination to clearly identify the target. Consequently, an increase in scope magnification does not necessarily facilitate TAT, and in some cases can significantly increase it.

The case where increased magnification almost always increases TAT is when the vegetation obscures the animal to the extent it cannot be identified by eye prior to rifle setup on the sticks, as would likely be the case as depicted in Photo 2, Photo 3, and Photo 5.  The inherent reduced viewing width associated high magnification could mean that the area initially being viewed through the scope literally does not contain the animal, requiring panning of the scope to identify it.

Based on the previous discussion and referenced photos, an obvious question would be “what should a scope’s lower-bound magnification be for the vegetation conditions noted?”. Based on my experience, I believe it should be 2 or lower for non-dangerous game, and certainly no greater than 3.

Once “the” animal is identified, the scope magnification may have to be increased to sufficiently identify the exact aim point on the animal. The actual magnification for this aim point is related to both the shot distance and the size of the target, such as either the heart or the lungs. The actual magnification can be expeditiously selected based on a predetermined “magnification multiplier” using the simple equation:

Required magnification = [(magnification multiplier) x (shot distance)]/100.

For the general area of the lungs on a broadside shot, many hunters believe a magnification multiplier of 3 is satisfactory. For example, if the actual shot distance is 150 yards or 150 meters, a scope magnification considered satisfactory would be [(3) x (150)] /100 = 4.5. Most hunters would round up and select a scope power of 5 for that situation. If the shot distance had been 300 yards or 300 meters, a scope magnification considered satisfactory would be [(3) x (300)] /100 = 9. Likewise, a shot distance of 50 yards or 50 meters would be [(3) x (50)] /100 = 1.5, potentially rounded up to 2, or to the scope’s minimum power.

On trophy hunts, my preferred target is the heart from all shot angles. Consequently, I use a magnification multiplier of 4. This multiplier is based on magnification judgements made while viewing the target identified in Photo 13, posted at 100 yards, at various magnifications. As indicated in the photo, the diameter of the heart is assumed to be 5 inches (13 cm) and the equivalent diameter of the lungs is assumed to be 10 inches (25 cm).

Hunters should determine their own scope magnification multiplier for the aim points of their choice based on assessments of target size (e.g. assumed or known heart or lung dimensions) posted at either 100 yards or 100 meters. The selected magnification multiplier should be as low as reasonably possible, as elevated magnifications to allow “aim small, hit small” can significantly reduce the scope’s sight-picture width. This sight picture is referred to as field of view (FOV), a topic that will be subsequently discussed.

Magnification multipliers can be used in conjunction with expected shot distances to assess if a scope’s magnification is satisfactory for the intended hunting scenario. These scenarios can be defined using criteria identified in eBook Chapter 9. Defining the hunting problem using the criteria suggested identifies the shot distances expected.

For example, if the average shot distance on a hunt is expected to be 135 yards (or meters) and a magnification multiplier of 4 is desired, the scope should have an available magnification of [(4) x (135)]/100 = 5.4, say 6 power. If a minimum shot distance of 40 yards is expected and a magnification multiplier of 3 is desired, the required magnification is [(3) x (40)] /100 = 1.2, or rounded up to the scope’s minimum magnification. If the maximum shot distance expected is 350 yards and a magnification multiplier of 3 is desired, the required magnification is [(3) x (350)] /100 = 10.5, likely rounded up to 11.

If the scope only has a maximum magnification of 9, this simple calculation indicates it could be marginal for use in the last hunting scenario example. A resulting hunting strategy could be to limit the maximum shot distance to better enable reasonable sighting on the lungs. The equation to expeditiously calculate the maximum shot distance that can be accommodated by the selected magnification multiplier is:

Maximum shot distance = [(max scope magnification) x (100)] /magnification multiplier

If the scope has a maximum magnification of 9, the maximum shot distance compatible with a magnification multiplier of 3 would be [(9) x (100)] /3 = 300 yards (or meters). If the scope has a maximum magnification of 9 and a magnification multiplier of 4 is desired, the maximum shot distance would be [(9) x (100)] / 4 = 225 yards (or meters).

Scope Focus

Hunting scopes can be either fixed or adjustable focus. If a scope is fixed focus, the focus of the scope cannot be adjusted based on the distance being viewed. The manufacturer has configured the scope’s optics so that it will be in precise focus at a fixed, arbitrary distance, typically 100 meters (109 yds) or 150 yards (136 m). The observed focus at distances more or less than the selected distance is typically more than satisfactory for identifying the animal and reasonably identifying the actual aim point.

A fixed-focus scope obviously eliminates the “duh” associated with the uncertainty of what to focus on in Photo 2, Photo 3, and Photo 5. Regardless, TAT is reduced with a fixed-focus scope. The penalty for this convenience is imprecision of the exact aim point at other than the arbitrary distance selected by the manufacturer, termed parallax. This imprecision is typically minor, on the order of about 1.5 inches (4 cm) at 500 yards (455 m). If the scope’s design has a fixed eye relief distance (discussed in the next section) that doesn’t change with changes in scope magnification, this potential parallax error is essentially negated with a consistent cheek weld on the stock that will produce a consistent placement of the eye.

The majority of scopes currently manufactured have an adjustable focus to get the target identified “to the fuzz”. As with magnification adjustments, refining the scope’s focus obviously increases TAT. Moreover, the arm movement associated with either a focus or magnification adjustment can be detected by the animals. Personal experience has shown that an undisciplined, heat-of-the-moment arm movement to adjust the scope’s focus can be sufficient to rocket a herd of blesbok into the next postal code.

Both TAT and arm movement required to adjust focus or scope power can be reduced with the aid of modern laser range finders. The PH can determine the shot distance while the hunting party is concealed, with the required scope adjustments made before the sticks are deployed.

Scope Eye Relief

Eye relief is simply the distance between the scope’s eye piece (ocular) and the shooter’s eye where a full scope sight picture can be obtained. Varying eye placement either forward or aft of this optically precise distance will produce some manner of shadow (black peripheral ring) around the sight picture. A consistent cheek weld to the stock at the eye relief required by the selected magnification is necessary to obtain a full-field sight picture.

The design and construction of some scopes prohibit obtaining a uniform eye relief distance with changes in scope magnification. On some scopes, changes in magnification between their minimum and maximum power can produce a change in eye relief ranging from about 0.1 inch (3 mm) to upwards of about 1 inch (25 mm). At the very least, such a pronounced change of 1 inch can result in an increased TAT in order to obtain a full-sight picture. Not only that, such a significant change in head placement can affect the shooting position as well as increase the potential for parallax, both detracting from shot-to-shot consistency. Each shooter must decide if the intended shooting application, shot distance, shooting position, and accuracy requirements can accommodate the potential inconsistency from variable eye relief associated with a particular scope.

Reticle Illumination

Modern rifle scopes can be optionally equipped with some degree of reticle illumination. Photo 6 and Photo 12 demonstrate the desirability of an illuminated reticle. Shadows (Photo 6) and the combination of shadows and animal hide color (Photo 12) can at least obscure an unilluminated reticle. Experience indicates that if the nyala in Photo 12 had also been back-lighted, I likely would not have been able to identify the exact reticle location on the animal. Personal experience also indicates that if the animal in Photo 12 had been a back-lighted blue wildebeest with a dark-gray-to-black hide, there would be no chance of identifying the reticle on the animal without it being illuminated.

Scope Field of View (FOV)

For purposes of this article, a scope’s field of view (FOV) or sight picture is simply the width of the area that can be viewed at any magnification available on the scope. The scope’s maximum FOV occurs at its minimum magnification; the scope’s minimum FOV occurs at its maximum magnification. The scope’s FOV at magnifications between these two extremes varies with the selected magnification and the actual distance to the target.  These FOV widths are not common to a particular scope power, and vary based on each manufacturer’s internal design of the scope.

The recent management hunts demonstrated that a scope’s FOV was at least as important as its magnification. These hunts conclusively demonstrated that there can never be too much FOV at any power. Unfortunately, they also clearly demonstrated that there can be insufficient FOV to facilitate a reasonable TAT based on hunt circumstances.

A narrow FOV at any magnification can significantly increase TAT because it is not wide enough to quickly identify the animal selected by the PH. Typical PH instructions can be “fourth animal to the right of the end animal on the left”. Panning a scope with a narrow FOV at the desired magnification multiplier simply to spot the reference animal so that the target animal can be identified not only increases TAT, but adds to hunter urgency to “take the shot”. To make matters worse, panning the rifle on the sticks adds to unnecessary movement that could potentially alert the animal or any animal in the herd.  

Scope manufacturers furnish both maximum and minimum FOVs at their respective magnifications. Unfortunately, I have never seen any that furnish FOV data for the magnifications “in between”. The scope magnifications between maximum and minimum are the ones predominantly used, and it stands to reason that the corresponding, intermediate FOVs would be the ones that need to be evaluated to determine if a scope was suitable for use in the intended hunting application.

On the recent management hunts, I had selected the scopes based solely on their magnification without considering their attendant FOVs at the shot distances identified in the hunting problem definition. Had I taken the time to calculate these FOVs at the expected magnifications and shot distances, I likely would have selected a different scope with significantly more FOV.

Calculation methods and example problems to determine FOVs between the manufacturer-furnished maximum and minimum is a technical “deep dive”. Furthermore, using these example problems to demonstrate how the calculated FOV values can be reasonably applied to real hunting circumstances is inconsistent with the generalized intent of this article. However, those interested in such a techno-excursion should grab their calculator and a fire extinguisher (cause that little hummer is gonna be smokin’) and proceed here.