Low Power Variable Optics: The Close and The Far

The world of Low Powered Variable Optics (LPVO) has bloomed in recent years with their increased use in both sporting and professional roles. Just about every optics company worth its glass has at least one LPVO and most have several to address either various price points or magnification ranges. This boom in optics has led to discussions over the ideal features for a LPVO. Due to other advances in optics there are actually 2 different classes of optics that now have the same magnification range: traditional LPVOs, which are geared towards action shooting sports and an assaulter type military role, and Extended Range Carbine Optics or Designated Marksman Optics (DMR), which are more geared towards shooting at distance.

Before we talk about the features that make up these two optic classes it is worth discussing the mechanics which created the overlap. The boom in LPVOs has coincided with a doubling of available zoom ratios from 3:1 or 4:1 up to 6:1 or even 8:1 and 10:1. The zoom ratio defines the range of magnification a scope can be capable of. As an example, the age old 3-9x hunting scope has a 3:1 zoom ratio, whereas the LVPO standard Schmidt and Bender Short Dot with its 1.1-4x has a zoom ratio of 4:1.  Higher zoom ratios allow precision optics to range from 3-18x (6:1 ratio) or 3-27x (9:1 ratio), but in LVPOs it allows for 1-5x, 1-6x, 1-8x, and in one case 1-10x. These ratios have both increased capability have also blurred the lines between two formerly distinct usage types of optics, traditional LVPOs (assaulter type optics) and Extended Range Carbine Optics (“Designated Marksman Optics”). What traditionally defined the difference between these optics were their magnification ranges. Assault gun optics were red dots with magnifiers or optics like the Short Dot in the 1-4 magnification range. Extended range carbine optics were 2-8x, 2.5-10x, or 3-9x, lacking a true 1x magnification setting or anything close to it. The growth in zoom ratios makes it possible for both sets of optics to have or be very near to 1x magnification and not give up much top end magnification. This means that to pick the scope that best suits your needs, we must look beyond magnification range and rather into the available features to balance them against end user needs.

Low Powered Variable Optics typically have a suite of features that do not sacrifice close range capability to gain extended range or conduct precise shot at closer ranges.  As Chuck Pressberg states, 90% plus of the time this optic is on 1x magnification and only zooms up for special circumstances.  Since close and fast is a priority, these optics typically have a very bright, read “sunny day, daylight visible”, red dot and typically do not illuminate the reticle. These optics focus on true 1x magnification and a big “eye-box” or area where the shooter’s eye can see through the scope un-occluded. Another priority is a wide field of view.  Those features create an optic that “disappears” or has nearly a seamless transition between the image in the optic and what your eyes are seeing outside of the optic. Reticles tend to have simple crosshairs with few calibrated sub tensions for various predicted bullet drops at distance. Windage marks will typically not be seen, unless they are calculated into the width of the various sub tension lines. Scopes will have capped turrets since they are often zeroed and any compensation for wind or extended range will be held in the reticle.  Finally, most scopes in the LPVO or assault gun class will be second focal plane, as opposed to the first focal plan of many DMR optics.

Second focal plane means the reticle and the illuminated dot will stay the same size regardless of which magnification setting the scope is on. A quick search of the internet will show that this is the worst possible thing to have in a scope because there is only 1 magnification setting, typically the highest, that the reticle will have accurate holds or measurements in. Though this is a legitimate downside and it is, which can be minimized through field tricks such as marking the ½ magnification setting on the magnification ring. Moreover, there are several distinct advantages associated with second focal plane optics.  The end user has a functional and readable reticle at all magnification settings. By contrast, the reticle which scales with magnification in a first focal plane optic may become cluttered and illegible at lower magnification or too bold at higher magnifications. Since the reticle stays the same size as the user zooms in, they will get a finer aiming point for a precision shot. For example, the illuminated dot will go from the size of the entire head box on a USPSA target down to the size of the A-zone “credit card”. Additionally, second focal plane optics tend to have fewer lenses, an arrangement that lends itself to a simpler and more robust optical mechanism, and which can offer both greater light transmission at lower cost, and the potential for a lighter scope.  All of these features combine to optimize the optic towards being “Aimpoint or EOTech fast” on close targets or in room, while still being able to zoom up to higher power to make a 25 yard shot into the A-zone on a USPSA target at speed.

In contrast to the assault gun style of LPVOs are Extended Range Carbine Optics or DMR optics. These optics tend to emphasize precision, while still retaining the ability to do close range work if needed. While LPVO spend most of their life on 1x, these optics spend most of their life at a magnification above 1x but may drop down to 1x for special circumstances. This mindset leads to a focus on higher top magnification even if that implies sacrificing true 1x at the low end – an example of this is the Leupold CQBSS which accepted 1.1x at the bottom end to achieve an 8x top magnification. Since longer range and accordingly higher magnification is the primary concern, these optics tend to have partial or fully illuminated reticles so that the features of the reticle may be used in waning light.  The reticles also tend to be more complex, often with “Christmas tree” or gridded style reticles that enable holding for drop and drift. The mechanics of higher magnification mean the eye box can be less forgiving and field of view tends to be a bit smaller than second focal plane LPVOs on the market. Precision style exposed turrets with locking mechanisms are common for elevation turrets and some optics may have dial able windage turrets as well. The most noticeable difference in this class of optics is the use of first focal plane reticles.

The use of a first focal plane reticle means that at all magnifications the reticle remains proportional to the target and the sub tensions are accurate. While this allows for milling targets or holding drops, it also means that a balance must be struck on how thick the reticle lines are.  A reticle that is readily usable on 1x will be too thick and obscure the target at higher magnification, and a reticle which is practically invisible at 1x will provide a fine aiming point for precision shots at higher magnification. A common compromise is to use a Christmas tree style reticle where at 1x forms an arrow pointing to the aiming point.  Another solution is to use thick rings between 50 and 70 minutes of angle in diameter to create an EOTech style halo for shooting at 1x. All of these features combine to optimize the optic towards use at intermediate to max effective range of the carbine, while still being usable if pressed into service for close targets. This optical capability is showcased in field style competitions where most targets tend to be farther than 100 yards but occasionally have close arrays when moving through the stage.

Will this solve the debate of which is the best LPVO or which LVPO should I get? No, but it will help provide the context to discussions where some people absolutely must have a Vortex Razor HD II or Swarovski z6i for the field of view, eye box, and bright dot and another person wants a reticle with better sub tensions and an illuminated reticle with wind holds.  Both are correct in their recommendations; however, they have distinctly different needs in an optic even when both have extremely similar magnification ranges.