The Magnification X-Factor

Making mountains out of molehills
6

Optics rifle with scope

High magnification (10 to 15X) is now available in scopes with a 3-4X bottom end for fast shooting in cover.

The hole looked the same after the second shot as after the first. Identical after a third. How could this be? At 24X, the crosswire had gyrated like a fly on a hot window!

Loath to push my luck, I lifted the 6mm Creedmoor off the bag. Its owner grinned wickedly and shook his head. “Two more.” The tightest three-shot knot I’d ever fired would become a 0.2" 5-shot group — still much better than the sight picture promised

“Hunters Now Fuel A Market In Variables To 18X, Even 20X. Deer Big As The Goodyear Blimp Float Across The Field.”

Rifle with scope

Hunting tactics have increasingly drifted from “jump-shooting” to “sniping” and manufacturers scope offerings reflect the shift.

The Reticle Dance

Watching your heartbeat in a crosswire is both comforting (you’re alive) and disconcerting (you can’t control the movement). Timing a shot to break with a reticle pause is devilishly difficult. The best you can do is minimize wobble and center it so the reticle spends more time near the middle than at orbit’s edge.

You can also throttle this frenetic dance by pruning magnification because at 4X your pulse is scarcely noticeable. Modest magnification also mutes the more unsettling shake of articulating joints and twitching muscles, unsteady field positions and the tug of gusty wind.

In both target and hunting scopes, magnification has climbed steadily. Soon after WWII Lyman sold huge 6X, 8X and 10X Targetspot scopes. Their legendary Alaskan model was 2-1/2X. Fecker listed target scopes of 4-1/2X to 16X. Its hunting models — 2-1/4X to 4X, competed with Weaver’s 3X, 4X and 5X scopes.

Hunters now fuel a market in variables to 18X, even 20X. Deer big as the Goodyear Blimp now float across the field of view. Target sights exceed 40X, double the magnification of the spotting scopes I used in competition!

Optics

Higher magnification brought additional dial options and more precise adjustments as shown on this Schmidt & Bender.

Coatings, Pupils, Brightness

Much is demanded of glass and coatings in high-power optics, as aberrations are magnified along with target images. Resolution improves only if the target remains sharp as it gets bigger. Like telephoto lenses, powerful riflescopes should cost enough to make you wince.

However crisp the image, its brightness is a slave to magnification, objective lens diameter and lens coatings. The common measure of brightness is Exit Pupil (EP) or the size of the pencil of light reaching your eye. EP = front lens diameter divided by power. Competitive shooting happens in good light, so the 1.05mm EP in Nightforce’s 42x44 Competition scope is no handicap.

All scopes worth considering now have “fully multi-coated” lenses. Reflection and refraction can steal 4 percent of incident light at each uncoated lens surface in a scope. The magnesium fluoride coating found to mitigate loss in the 1930s has now been replaced by multiple compounds that pass individual wavelengths much better. “Fully” means all lens surfaces are coated.

Optics

This beefy Nightforce has the wide power range, increasingly common on hunting and target scopes.

Compromising With Power

Field of view is a clear casualty of magnification. Unlike EP, it varies among scopes of identical power and front lens diameter. Swarovski’s Z6 2.5-15X has a 100-yard field of 8.1 feet at 15X (for 44 or 56mm objectives). The field of a Nightforce NXS 3.5-15X is 7.1 feet at 15X.

A Zeiss Conquest 4-16X gives you 28.5 feet at 4X, same as a Leupold 4-24x VX-6HD. But Leupold’s VX-R 4-12x40 at 4X shows just 21.5 feet, a Vortex 4-16x Viper 27.4. Diminutive fields limit some sights to bipod and bench. At its top end, Schmidt & Bender’s PM II 12-50X delivers a 3-ft. field while March offers sights of 60X, even 80X!

Generally, increasing power reduces eye relief and the size of a scope’s “eye-box” — the latitude your eye has in getting a full field of view.

Still, high magnification has much to recommend it. Rifles and loads reach accurately beyond the practical range of yesteryear’s optics. In many places and for many shooters, hunting tactics are shifting from jump-shooting to sniping. Better optics in big tubes yield bright, needle-sharp images.

Broad power ranges — the top power five- and six-times the bottom in 3-15X and 4-24X scopes — give you precision and panoramic field. First-focal-plane reticles remain a constant size in relation to the target throughout the scope’s power range, allowing you to judge distance at any setting. Finally, many powerful hunting scopes now complement the profile of slender rifles and add little weight. Swarovski’s 3.5-18x44 scales less than a pound!

Want to hit a prairie dog’s noggin at 300 long steps or a big whitetail bounding through cover at spittin’ distance with the same scope? Now you can!

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