Web Extra: Optics In The Field


Optics In The Field

By Sam Fadala
Photos Nick and Judy Fadala

Steady View

Sitting stance to steady the glass for a clean, sharp game-finding view. Elbows are on knees for extra support, with back settled firmly against tree.

“I would never pay that much for those things,” my friend said as he eyed the Leupold Golden Ring 10×42 binoculars hanging around my neck. “I just wouldn’t.” I smiled. The glass had recently sucked up a whitetail buck bedded like a worm in a cocoon along a creek bottom. I came up with my usual argument: that I’d rather hunt with a decent scoped military rifle and super binoculars than the finest firearm in Christendom and a low-grade glass. My point was made and I clamped onto it like a Gila monster. My buddy nodded and said that maybe I was right, maybe. I knew I was right. Good binoculars are a pay-back investment. They earn their keep by sorting game from the niche, judging bucks, bulls, and boars, and of equal importance—promoting a superior experience in the field. What hunter doesn’t enjoy bringing wildlife into his lap optically? From the top of a windmill stand I watched a story unfold in the cinema of my binoculars—a golden eagle subduing a full-grown mule deer doe—grim but a part of Mother Nature’s scheme.

I hunt with binoculars. My glasses find wild animals. It’s not that I’m blessed as a game-spotter. It’s just that I was taught by my mentors to use magnification to locate wild animals, emphasis on “locate.” And not only in open country. The glass has pulled many bedded and feeding animals out of black timber and thicket. The goal of this little walk in the woods is simplifying the process of choosing binoculars for finding wildlife and enhancing time spent in the outdoors. I am not an optical engineer. I know of no outdoor sports writer who is, although some like to spout great big words on the subject like a whale on the ocean. If I had to explain those terms I’d stammer and stutter like Porky Pig in the cartoons. But I know a good glass when I look through one. And I have looked through a good many over the years. Rather than going into the physics of light, which require Einsteinium formulas, let’s consider the following practical factors: optical resolution, light transmission, color rendition, edge sharpness, field of view, focus, prism design, construction, tired eyes (collimation), magnification, ergonomics, and size/weight.

binoculars carry

Showing how nicely roof prism binoculars carry close to the chest when the strap is short.

Optical Resolution

From the practical point of view, can be thought of as sharpness, that crisp, clear image that requires no scientific knowledge to understand because we can see the difference. Among the factors that provide high optical resolution, are size and quality of objective lenses—those farthest from the eyes as opposed to the ocular lenses close to the eye. Objective lenses are measured in millimeters. Therefore, a 10×42 unit has objective lenses 42mm wide. These front-mounted lenses capture the image to be focused onto the lenses inside the barrels of the binocular. We won’t have the equipment to scientifically test high resolution, although reading lines per millimeter on a grid is easy enough. I prefer testing optical resolution by looking into shady areas with binoculars on a tripod to eliminate human error. A fair to middling binocular will put on a good show in the sun. But it takes a higher pedigree to define objects in the shade, such as a buck bedded under a tree. Binoculars with high resolution reveal a rusty tin can as a rusty tin can, not “an object.” Reading distant signs and license plates is a good test. I have not given contrast a special place because I see it as part of resolution. The high resolution glass reveals contrast between a branch and an antler.

The short strap

The short strap can be used to steady the glass by putting pressure on the strap, something like using a hasty sling in rifle shooting.

Light Transmission

This is partially controlled by prisms, number six on our list of criteria coming up. Brightness is a wonderful asset, but not at the sacrifice of high resolution and contrast. Obviously, the brighter the image coming to the eye, the better to see it, although the human pupil can assimilate only so much light. Here again, the larger objective lens is helpful, although it also contributes to number 10 on our list, size and weight. Top binoculars transmit light well partially due to a microscopically thin lens coating of what are known as rare earth molecules such as magnesium fluoride. Forget the science. Just look through the glass in lower light. The image is either bright or it is not. The Leupold binoculars referred to as an example in this little campfire chat have what is known as phase coated prisms along with lens surface coating. Leupold’s Golden Ring glass also has the Index Matched Lens System ™. Each lens coating is matched specifically to the type of glass as well as lens placement in the binocular barrels.


Standing with walking stick used to steady binoculars. This is a great way to either still-hunt or spot-and-stalk because it provides a good steady game-finding picture while allowing the hunter to keep on moving.

Color Rendition

This is important in the game field because a glass that faithfully distinguishes between hues aids greatly in revealing the difference between a log on the ground and a bedded animal. Color rendition also improves texture variation. One afternoon on a Coues deer hunt my partner and I simultaneously picked up two oak logs lying in open shade about 500 yards out. Our binoculars seemed to possess a mind of their own as they returned time and again to the logs. Finally, one of the “logs” got up and walked away, a premium buck. Our glasses were not up to revealing the exact color or texture of the “logs.” Had we better binoculars and we would have stalked that “log.”

The Leupold Golden Ring

The Leupold Golden Ring has three-position twist-up eyecups. Here the cups are shown in full up and half up positions. The hunter chooses which suits his or her eyes best.

Edge Sharpness

This is also easy to detect by you and me, the ordinary hunter who does not hold a degree in the physical properties of light. “Sneak” a peek at the outer corners of the view in the glass while holding the glass still (do not pan). Is edge image sharp or fuzzy? Edge sharpness is nice because it brings the entire field of view into a “flat-screen” view, rather than just the centermost section. High quality binoculars show high optical resolution over the entire picture, not just the center, although the central portion remains most important.

Leupold 10x42

This ring is an interpupillary distance lock, another good idea on the Leupold 10×42 Golden Ring binoculars. After the barrels are adjusted so that both eyes are looking into the centers of the ocular lenses, the ring is turned to lock the barrels in place.

Field Of View

The main value I see in a broad field view is ability to examine a larger plot of game habitat without moving the glass a lot. I have a handy high-quality B&L 7×26 glass I use from tree stand or ground blind and in the African bush. Field of view (FOV) is 363 feet at 1,000 yards. I have a 10×50 glass with an FOV of 6 degrees and 30 minutes—113 meters or 371 feet at 1,000 yards. As magnification increases, FOV normally decreases. But there are special wide-angle binoculars that alter that condition. Do not select binoculars on FOV alone. My Leupold 10×42 has an FOV of 386 feet at 1,000 yards. If I were trying to pick a buck up across a canyon and into the trees a thousand yards away, which is no great distance for good binoculars, my view would be wider than a football field and that is more than adequate.

Focus Wheel

The focus wheel on the Leupold 10×42 Golden Ring glass is generously sized and precise in movement.


There are three main types of focus—binoculars that through design do not require focusing at all, individual ocular focus and central focus with a wheel. Central focus with a wheel is most common and generally preferred, although I own a pair of Zeiss binoculars originally issued to the Chinese Army that are individual focus and I have no problem creating a sharp image with that glass. I set both lenses on zero because my eyes are the same. Zero is good for longer distances. For closer views with this glass, the ocular lenses are set on plus-one. The process is simple, fast, and easy to get used to. Regardless, the majority of better binoculars today have central focus capability. I like this because part of locating harder-to-see animals in the field is accomplished by “hardening” and “softening” the view—that is, altering focus “back and forth” and that’s best done with a focus wheel.

Prism Design

There are basically two types: roof and porro. I have 12×50 Bushnell reverse porro prism binoculars. Rather than mounting the prism horizontally, so that the binocular becomes wider, these prisms are aligned vertically to retain the clean lines of this glass. The best prisms in either roof or porro match up favorably. Roof has the advantage of slimmer overall lines with friendlier ergonomics. That’s the only advantage over porro prisms but it’s a big one. Choosing a big game hunting binocular by virtue of prism design alone, however, counts for nothing. Show me a bright glass and I’m happy with either type. Prisms separate “field glasses” from real binoculars since the former have no prisms.

Sam hunts wild turkey

Sam hunts wild turkey using binoculars to locate flocks feeding or moving about in their habitat. Once spotted, staking for a close shot is not too difficult.


Higher end glasses are built to stand up to normal field use — and a bit more. I recall a hunt in Mexico where the local guides were given binoculars of what I call medium quality. Not knowing a lot about care of optics, these fellows, mostly vaqueros, were pretty rough on them. In one week’s time, every glass was out of collimation, the next feature on our list related to internal construction. While it’s never acceptable to abuse an optical instrument, sometimes binoculars do fall into unfriendly contact in the field. Except for a drop on a boulder, and sometimes even that, a good glass survives the blow. Our exemplary Leupold 10×42 is constructed with a “brown armor coating” that acts as a shock absorber and abrasion barrier. Waterproof, this particular glass is guaranteed for life. Barring suffering a direct attack from a Cape buffalo or ending up under the rump of an elephant, this and other top end binoculars will serve for lifetimes — plural. The lenses within the barrels are imprisoned not with little clips, but rather sturdy dividers for proper distance retention.

Tired Eyes

Long periods of intense game finding resulting in fatigue are caused by several factors, collimation failure being at the forefront of the problem. Collimation is the precise alignment of the two barrels. No imagination is required to guess what happens when one barrel is looking in one direction, the other in different direction. This “cross-eyed” effect forces eyes to overwork as they try to visually accommodate the problem. Collimation goes back to construction. Quality binoculars are constructed to align both barrels and keep them that way.

Find Game

Find game here? Yes, with the help of binoculars not merely scanning but in the finding mode.


I often read that 10X is the maximum magnification for successful hand control, anything more powerful requiring a tripod. This is rubbish. Ability to hand-hold binoculars of high magnification is individual. My personal limit is 12X, provided I sit for a steady view or use my walking staff. I can also employ my 15X Swarovski binoculars to good advantage off of the stick or sitting with back firm against a backdrop. But I much prefer a tripod for best viewing over a long period of time with this much magnification. For open country, I like a powerful glass. But I have seen hunters do good work with 7X or 8X. And therefore cannot recommend any given power as the only correct magnification.


This is a pretty word for “hand fit.” I have packed binoculars in the field that fit the hand like a bucket for a bonnet on a chicken. I admit I own two heavy and unwieldy glasses I have no intention of retiring. One is 10X, the other 15X. Both are fat in the hand. Neither causes me particular discomfort in the field, partly because I learned about the short strap a long time ago. Also, there are harnesses that pin big binos down. The exemplary Leupold 10×42, on the other hand, was designed from scratch with hand-fit in mind. And fit they do. A hunter might want to consider handling a glass he or she intends to live with a long time before punishing the billfold for big bucks. Ergonomics is not size and weight, next on the list. It is friendly fit in the hand.

Kobus Schoeman

Here is Kobus Schoeman, outfitter and instructor, helping a student sight a rifle. Binoculars save walking here, and time, during a busy Africa PH course.

Size And Weight

I give the nod to roof prism binoculars here. The roof prism design promotes compactness, and compactness in turn promises lighter weight. I’ve carried binoculars on a strap around my neck for so many years that there is a permanent indentation where the strap rides. Nonetheless, I have suffered no lasting ill effect from carrying a big glass. At the same time, I appreciate lighter binoculars in tough country. I also like the more compact lightweight glass when extensive travel is necessary. As a licensed PH in Africa, I need top rated binoculars to help locate that black wildebeest, zebra (king of camouflage), as well as other fauna that roam the bushveldt. I won’t sentence my binos to the hold of the airplane, which means they’re in my carry-ons, which precludes the great big glass. Fortunately, hunters can have their cake and it, too, because there are binoculars today that perform beyond their size and weight.

One of my writer friends, a well-known chap in the world of big game hunting, disagrees. But I have found the Coues deer of the Southwest and Northern Mexico the most challenging trophy of my hunting career. I suppose a bongo in a rain forest might be tougher or perhaps a Marco Polo sheep in the rarified air of their high mountain habitat. But hunting Mexico and Arizona I managed to collect 15 B&C-worthy bucks at the time they were taken. I worked hard for every one. I planned to go no more for trophy Coues, being satisfied to hunt no more for “heads.”

But Patrick Holehan of Gone Hunting Outfitters in Tucson, Arizona invited me to Mexico and I couldn’t refuse. Patrick is a wonder on Coues. He’s a glass man of the highest caliber. He lifted buck after buck out of the rugged tangle of Sonoran mountains, putting on a show of game-finding I have never matched. It was, however, his assistant outfitter, John Mullens, who spotted the buck I eventually took on that trip — 114 4/8 B&C. I don’t “do the book.” But I do enjoy taking a trophy, and I know what got that buck for me. It was optics — high quality binoculars along with a great spotting scope turned the trick.
Good binoculars are selling better than ever. The serious hunter has reasoned that the expense is minimal compared against the overall cost of hunting. And that hunter is right!

The pronghorn

The pronghorn lives in open country. Sam has taken many antelope with iron-sighted muzzleloaders, .30-30s and .38-55 rifles by spotting first with binoculars and then working out a good stalk to get close.


1. Get steady – you’ll find very little game with a shaky picture. Sit with back supported if possible, elbows on knees. Use a walking stick (staff) for “tripod stability.” The stick represents one leg of a tripod, the hunter’s legs forming numbers two and three.

2. Get comfortable, which may require wearing an extra outer garment in early morning and late afternoon. Shivering hunter finds little game.

3. For center focus glasses, work focus wheel to change picture texture.

4. Quadrant the glassing area—set it off into imaginary sub-spots for viewing.

5. Look for subtle more than obvious. Rather than a whole elk or deer standing out on a ridge, study for antler tip or rump patch, shiny eye in brush or grass. You will found more “partially showing” game than standing out game.

6. Spot and stalk—emphasis on spot—walk, look, look, walk. Let your binoculars do a lot of the walking for you to increase game-finding odds.

7. Know your game—spend viewing time glassing most likely spots chosen from experience.

8. Practice provides confidence—keep practicing. If at first you don’t succeed, try again—and again.

9. Look especially hard early and late in the day for big game animals such as deer and elk that often bed during bright daylight hours.

10. How long to glass one area? Look long enough to be satisfied that you’ve done your best searching out a prime piece of ground. Then move on.

11. If a powerful glass is too strong for you to hold steady, invest in a lightweight tripod and use it.

12. Check differences in color and texture. Wild animals blend with surroundings. But they also vary in color and texture.

13. Look for movement. Sometimes movement, especially bedded game, is subtle and may show only as brush or grass in motion not an animal.

14. Watch for peripheral motion. Sometimes the movement of animals and birds indicates big game nearby.

15. Rock or log may become deer or elk. Never be embarrassed about mistaking these for game. It just proves that you were searching hard.

16. Recognize what binoculars do, which is much more than magnify. They isolate a chunk of territory for scrutiny, focus concentration on specific spots, optically separate game from habitat, show detail in line, form, and color, promote hunter interest, save superfluous hiking, and improve hunter attitude by increasing hunter success.

17. Glass heavy cover as well as open terrain. A glass increases hunter ability to look deeper into brush and trees.

18. Wear a hat that shades the eyes. This is most important when having to glass into the sun.

19. Shorten the binocular strap. Even the best binoculars often come with straps that put the glass down around the belt line. A shorter strap prevents bounce and also offers a steadying effect like the hasty sling method of rifle shooting. Or go with a strap that holds the glass firmly against the chest.

20. Consider binoculars prime hunting tools residing only behind the rifle, GPS, and other important implements. As the late John Doyle, inveterate Coues hunter, said, “Binoculars are the Eyes of the Hunter.”

Quotation from famous 19th century Arctic explorer, Vilhjaimur Stefansson:

In hunting on the grassy plains of the Arctic, a good pair of glasses and knowledge of their use are about as important as the quality of your rifle and the pair of legs that carry you. I have found it as difficult to teach a new man the proper use of field glasses as to teach the use of the rifle. The green man stands erect with he heels together, lifts the glass jauntily to his eyes and spins slowly around on one heel, taking from half a minute to a minute a complete survey of the horizon. Then he announces that there is no game in sight. The experienced hunter will take pains to find the best place to sit down. If the landscape is well within the power of his glasses he will probably rest his elbows on his knees, but if the distance is great or if the wind is blowing, he will lie down flat with elbows on the ground, or will build up out of a set of stones or any material available a rest [so] the glasses cannot be shaken by the wind.