Imperfection of Vision

By olegv published on in Ammunition, Firearms, Gun Gear

Looking at historic arms, we often see sights graduated to extreme distances. Rifle open sights were marked out past a mile, and pistol sights sometimes went past half a mile. With such inspiring examples, how do people justify festooning their modern guns with lights, lasers, red dots and tactical kitchen sinks? And in defensive encounters, how do we explain needing all kinds of tritium, fiber optic and laser aids to shoot at five paces when the ancestors apparently slew sabertooths at a mile with roughly pointed single shot flintlocks? Maybe the prowess of the yesteryear’s heroes was a bit exaggerated, but what of the marksmen at Camp Perry punching tiny bullseyes at multiple hundreds of yards with open and peep sights? The answer is that they aren’t sighting with the same devices we are.

SMLE rear sight was graduated to 2000m

SMLE rear sight was graduated to 2000m

A typical marksmanship competitor is relatively young, with good eye sight and shoots in daytime. The pupil of his eye closes almost entirely, like a camera lens stopping down, providing extensive depth of field that renders not only the front sight but also the target and the rear sight reasonably sharply. Small apertures in peep sights enhance that effect. Most people can do fairly well under the ideal lighting conditions. The trouble begins when the light levels drop, as is typical during most defensive encounters. First, the pupil of the eye must open to allow more light, simultaneously reducing the depth of field. Since older eyes don’t adjust to the dark as well as the younger eyes, some of us would need to illuminate the adversary even at dusk. At this point in time, red dot sights really shine, as they allow to focus on the target and still get a reference for aiming. Keep in mind that the targets used at Camp Perry don’t move, so it’s easy to focus on the front sight. In defensive situations, our adversaries usually move, requiring frequent refocusing on them to keep track of the threat’s actions and location. A person watching a foe would have to have great presence of mind to focus away from the adversary’s weapon to his own front sight as required for accurate return fire.

Browning High Power sights were marked to 500m

Browning High Power sights were marked to 500m

The trouble with wide open pupils is that our eyes aren’t perfect lenses. As the periphery of the ocular lens is engaged, aberrations like astigmatism become more visible and suddenly the crisp round reticle of a red dot sight becomes a smeared vertical line. At that point, using any sights becomes very difficult. The solution is to project the aiming reference onto the target itself using a laser. The dot wouldn’t have to be perfectly focused to be useful for accurate fire. That is especially important for older shooters using pocket pistols with abbreviated sights. I have personally witnessed a man who could barely hit a life size silhouette with a pocket .32 put the whole magazine into the X at the same 20 feet by using a CTC laser. He could even place accurate shots from retention position, with only a couple of rounds required to get used to the trigger pull.

In bright light, pupils contract and provide better depth of field

In bright light, pupils contract and provide better depth of field

 

Bersa Thunder 9 with C5L light/laser sight

Bersa Thunder 9 with compact C5L Viridian light & green laser

The trouble with lasers and electronic sights is that any gear can be broken, or go out of adjustment, or the batteries might fail. The emitter lens of a laser may become smeared with blood or mud. What to do then? The last technological aid for the defender is tracer ammunition. Modern tracers are non-corrosive and many types light up right at the muzzle, making them perfect for use in pistols. Having obtained aim with sights, a laser or an optic, the shooter can verify aim by observation of the trace. Though visible in daylight, these come into their own at dusk or at night, precisely when most violent crime happens. So the combination of optics, laser and tracers for a defensive firearms isn’t an exercise in needless complexity but a “belt and suspenders” approach to ensure that failure of one component doesn’t leave us shooting aimlessly.

SBR Lasermatch tracer ammunition.

SBR non-corrosive Lasermatch tracer ammunition.

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