This article by John Barsness originally appeared on the website www.opticstalk.com, where he writes a monthly column on some aspect of optics. John and his wife Eileen Clarke also publish their own on-line magazine, RIFLE LOONY NEWS, available through their website www.riflesandrecipes.com.

A spotting scope’s use in hunting often begins before the season actually opens. A spotting scope allows the hunter to “scout” big game animals without disturbing them. This works not just in the wide-open West but anywhere some distance can be found, whether across a Midwestern farm field or from ridge to ridge in the Appalachians.

Americans hunt deer more than any other big game, and a spotting scope is particularly useful when scouting for either mule deer or whitetails in late summer before they shed the velvet on their new antlers. At this time of year the antlers are soft and tender, and even big whitetail bucks will spend more time in the open. Also, the coats of summer deer are reddish, so they stand out at long distances.

Bucks also tend to hang out together before their antlers harden. They’re not producing as much testosterone as they will later in the fall, so are a lot more mellow around their potential rivals. During the last days of August I’ve seen as many as 14 branch-antlered whitetail bucks in one small field, and as many as six mule deer bucks bedded on a mountainside. In the West you’ll often see several bull elk together, and in the Rockies and the North several moose. Such sightings encourage hope and persistence during the upcoming season!
These bachelor herds break up during the rut, but their members will still be somewhere around. Whitetails, especially, tend to stay in the same general area. Mule deer and moose may wander further, but will generally be within a mile or two of their late-summer hangouts. Elk will wander the farthest.

One thing quickly discovered during such scouting is that really high-powered spotting scopes aren’t quite as useful as many hunters would imagine. Two things interfere with a clear view when a scope is cranked much above 40x: a small exit pupil and heat waves.
The first is most important during dawn and dusk, when game animals are most active. A 2mm exit pupil is marginal but OK in dim light; anything less results in a view with almost no contrast and detail. A spotting scope with a 60mm objective has a 1.5mm exit pupil at 40x. Crank the same scope up to 60x and the exit pupil shrinks to 1mm. This just doesn’t get it done in anything except bright sunlight, the reason that serious hunters often invest in yet another spotting scope with a 75-80mm objective lens. These can be turned up to 40x and still have an exit pupil of 2mm.

The other problem occurs as the sun rises higher, when heat waves begin to rise as well. The image may be bright at 60x, but you won’t be able to see much detail because heat waves interfere. On the high plains in early autumn I’ve seen heat waves interfere so much with the view that by 9:00 in the morning that it’s impossible to see horns on any pronghorn much more than half a mile away. You can tell that their head is black, both because of the black horns and the dark throat patch, but you can’t actually see the horns.

This is why most of my hunting scopes have eyepieces that don’t go above 40x or 45x. There’s just too little practical use for higher magnifications. However, if you like to use a spotting scope for, say, star gazing, then higher magnifications can be useful. At night there’s no problem with heat waves, both because of cooler temperatures and because the scope is pointed upward, away from heat rising from the ground. It’s pretty cool to be able to see the moons of Jupiter or the rings of Saturn.

Some spotting scope purists insist on fixed-magnification eyepieces, since these usually provide a slightly sharper view than variable eyepieces. This may be true in an absolute sense, but hunting involves a wide range of light and terrain. You’ll actually be able to see much better with a slightly less-sharp variable eyepiece, because the magnification can be “tuned” to the light and atmospheric conditions.

Something in the 12-40x or 15-45x range is just about perfect, partly because the lowest magnification provides a wide field of view. When hunting, spotting scopes are often used along with a binocular. The game is often spotted with the binocular, and then the scope is used to zoom in for a better view, allowing us to evaluate the animal itself and, sometimes, details in the terrain in preparation for a stalk.

It also saves us time and effort. Both are often at a premium. A spotting scope allows us to get a good look at the horns or antlers of animal before making a long cross-canyon hike. This isn’t only a matter of trophy evaluation, but often of making sure the animal is legal. Many areas require a certain number of tines for antlered game to be legal, and in at least parts of British Columbia a mountain ram must have a certain number of “growth rings” on his horns. This really requires good glass. Even bears require evaluation. Bigger, mature bears have certain characteristics, such as wide-set ears, that set them apart from younger bears. Often these are only visible through a good spotting scope.

Spotting scopes can be purchased with both straight and angled eyepieces. Both styles have their adherents. An angled eyepiece allows glassing both above and below us more comfortably, especially when we’re lying down (a frequent position in open-country hunting). An angled eyepiece can also be used on the level, by turning the scope so that the eyepiece is level with the body, but some people find it really hard to locate anything in the scope with this set-up, much preferring a straight eyepiece.

I am of two minds here. I find an angled eyepiece much more comfortable when looking both above and below me, but often get frustrated when trying to find something I just saw through binoculars—especially if there are only a few minutes of light left, or the animal is moving. I also find that when sitting up to glass a straight eyepiece is more comfortable, and sitting is also a frequent glassing position in some hunting country. I also prefer a straight eyepiece when glassing from a vehicle, with the scope on a window mount—though that can vary with the angle too.

What a hunter really needs is an eyepiece that can be tilted anywhere from straight to a 45-degree angle. This feature is rarely found, however—and to my knowledge never found in a really top-notch scope. So my advice would be to borrow spotting scopes with both straight and angled eyepieces and really give them a workout before making your final decision. I own both types, an indication of how ambivalent I am on the subject.

To be truly useful a spotting scope much be mounted on something to keep it steady. I have seen people place them on the crown on a cowboy hat that’s sitting on a rock or log, and some hunters who mostly glass from vehicles keep a spotter on a shoulder stock. These will work, but aren’t nearly as good as a window mount or a good tripod.

Part of the reason for using a window-mount or tripod is scanning. We do this not only to find an animal we’ve already glassed through binoculars, but when actually looking for game. Yes, a spotting scope can be used to find animals, and at really long distances is more useful than conventional binoculars of 8-10x. The trick is to examine each piece of the country in an organized way, and turning the head of a tripod is perfect for this purpose.
(Another trick when using a spotting scope for actually finding game is to place a piece of tape over the “off” lens of your shooting glasses—or, if you’re like me, your everyday glasses. We feel eyestrain when looking for long periods through a spotting scope either because of muscle fatigue in our off eyelids, due to keeping the off eye closed, or the off eye trying to focus along with your primary eye. Placing a piece of tape across one lens of your glasses allows glassing with both eyes open, and is a LOT more comfortable during long periods of looking, believe me. I normally keep a couple strips of tape on the scope itself, just for this purpose. Electrical tape works fine.)

The rule of thumb with tripods is that the bigger the scope, and the higher off the ground it will be, the bigger and heavier the tripod. The heavier and higher the scope, the harder it is to keep steady, and if the scope isn’t steady we won’t see distant detail—the reason for a spotting scope in the first place.

Unfortunately this conflicts with a lot of hunting. Ideally we’d pick a scope with an objective in the 80mm class, in order to see better in dim light. We’d like to pair this with a tall, heavy tripod. But just try to carry both a big, heavy tripod and a big, heavy 80mm spotting scope in the field.

This is why many serious hunters have both an 80mm scope, used almost entirely from or near a vehicle (whether on window mount or a full-size tripod) and a smaller 60mm scope, used with a small tripod, for carrying in the field. If you choose carefully, a 60mm scope and short tripod (used for no more than sitting height) can fit into a daypack for carrying into the field. This is impossible with a really big scope and full-size tripod.

One trick that can be used to steady any tripod-mounted scope, especially in the wind, is to drape something relatively heavy over the scope itself. I’ve placed a hunting jacket, for instance, over a scope to tame wind vibrations.

Some hunters also find a truly compact spotting scope useful. If glassing isn’t going to be for extended periods, a small spotter can even be substituted for both binoculars and a spotting scope. On a caribou hunt in the Northwest Territories a few years ago I decided to test a then-new 10-20x compact spotting scope, a nifty little thing about 10” long and weighing less than an average 8×40 binocular.

After one day of carrying both a full-size binocular and the little spotter, I left the binocular back in camp. When set on 10x the little scope worked fine for the minimal amount of glassing needed to find caribou on the tundra (if there, caribou are pretty obvious!), and when cranked up to 20x and placed on my shooting sticks the scope worked fine for evaluating antlers up to a mile away.

As with other optics, I have too darn many spotting scopes, though I use them all at one time or another. But for the average hunter I’d suggest starting with a good 60mm-objective scope, with a variable eyepiece topping out at around 40x to 45x, combined with a compact tripod that can be used either while sitting or lying down, and a window mount. Such an outfit will take care of 90% of the glassing any hunter requires from a spotting scope.