Zoom vs Fixed Power

There are pros and cons to zoom and fixed-power spotting scopes, beginning with size and weight. The average fixed power is about 10 ounces lighter than the zoom scopes, and it's probably about an inch shorter. For these reasons, as well as the fact that they're less complicated, I generally find fixed-power spotting scopes more suited for sniping.

Earlier we observed that 30x is about the maximum magnification for a spotting scope, since higher powers become too readily disrupted by mirage. Considering this ceiling, it's questionable that you can exploit fully these zoom models, nearly all of which go well over 30x, some even to 60x. This doesn't mean the manufacturers are evil or making inappropriate products; it's just that these aren't best suited to sniping. Such higher magnification works just fine on a firing range or perhaps when scanning for game in mountain country.

Still, though, there's room for compromise. Some quality spotting scopes are convertible

Sniper ExploitFixed Power SniperFixed Power Sniper

Suspend a sandbag beneath a tripod to stabilize it solidly on uneven ground or during windy conditions.

attention was focused on a particular taxiway; once taped firmly in place, my scope was locked-in to just that spot.

Clamp mounts are available, too, by which you can attach your scope to an automobile window or a chair back and should be quite useful for law enforcement applications.

While earlier I advocated holding binocular eyepieces against your eyebrows for best results, now I must tell you exactly the opposite when using a spotting scope. Once it's focused on the intended location, don't touch it at all. Due to its high magnification, the tiniest vibrations will degrade the image in ways not readily noticed. The surest way to steady a tripod-mounted scope on a windy day or on uneven ground is to suspend a sandbag beneath its center. This also works great when using a tripod as a shooting rest.

And when using a spotting scope, be sure to rest your eye frequently and switch to binoculars from time to time to prevent eyestrain. By SOP, you should switch roles and optics with your partner on the hour to avoid straining your vision.

Tripod Mounted Rifle RestTripod Mounted Rifle RestFixed Power Sniper

Shining a SureFire flashlight in a rifle scope's objective lens projected this circle of focused light 3 1/2 inches beyond the scope, exactly at correct eye relief. This circle of light—the exit pupil—widens as you reduce magnification and narrows when you increase magnification.

devices is callcd "relative brightness," which only requires that you square the exit pupil so that differences become algebraic and advantages more obvious, as shown here:







x 3



x 4



x 5



x 6



x 7


The third way to measure and race light passage is the "twilight factor," which gives more weight to a device's low-light magnification and thus emphasizes the ability to resolve detail at dusk and in moonlight. This is an especially-important rating for sniping observation. But to yield a valid comparison, you should only compare twilight factors for two devices having similar exit pupils or there's no significance in the rating.

To compute twilight factor, multiply the device's objective tens diameter by its power, then find this number's square root. Sincc both 7x35 and 10x50 binoculars have 5mm exit pupils, let's compare their twilight factors to determine which will allow better low-light resolution:

7 x 35 - 245, which has a square root 15.6 - Twilight Factor

10 x 50 = 500, which has a square root 22.4 = Twilight Factor

Thus, the 10x50 binos have a decisively superior twilight factor; indeed, a law enforcement agency once phoned me late one afternoon and asked what kind of binoculars to use that night for a drug case surveillance, 7x35 or 10x50, so now you'll understand why I recommended the latter. But I also asked the law officer if he'd be packing in somewhere or operating undercover, sincc the 10x50s are heavier and more difficult to conceal than 7x35s, criteria I cite because there are more considerations than merely numerical ratings.

Scope Officer

waves, you'll have problems with a spotting scope of more than about 30x. With rifle scopes, the maximum magnification is about 12x before mirage seriously starts degrading images.

The upper limit on binocular magnification is dictated by how steadily one can hold them. With your body braced, you still can clearly resolve distant objects when using lOx or I2x binos. Any greater power and there's just too much unsteadiness in the human body to allow-clear long-range viewing.

If your team has available both spotting scope and binoculars, the binos can be relatively lightweight 7x or 8x. However, in cases where no spotting scope's available, a team needs binos of at least lOx since they'll be employed not just to detect targets but also to observe and adjust the snipers fire. But ideally, you should have several overlapping optical devices.

Was this article helpful?

0 0
Hunting Mastery Selected Tips

Hunting Mastery Selected Tips

Deer hunting is an interesting thing that reminds you of those golden old ages of 19th centuries, where a handsome hunk well equipped with all hunting material rides on horse searching for his target animal either for the purpose of displaying his masculine powers or for enticing and wooing his lady love.

Get My Free Ebook

Post a comment