Home : Optics : Choosing : Bird Watcher's Digest: Optics: Spotting Scopes

About Spotting Scopes

Scope Terms

Objective Lens Eyepiece Erecting Prisms Aperture Magnification Eye Relief Chromatic Aberration Angled or Straight? Comparing Large Scopes Comparing Small Scopes For a scopes comparison, please download the accompanying chart, which lists the models mentioned here. You will need Adobe Acrobat to read the chart. You can get a free copy by visiting Adobe's website.

Objective Lens

This is the lens in front, nearest the object at which you're looking. It focuses an upside down and backward image of the object.

Eyepiece

The lens you look through is the eyepiece. It magnifies the image created by the objective lens and presents it to the eye. Many scopes allow you to change eyepieces.

Erecting Prisms

These prisms flip the image right side up and left to right, to make it look normal. They fit between the objective lens and the eyepiece, near the back of the scope body.

Aperture

This is the diameter of the front lens, usually expressed in millimeters (mm). In describing a scope, the aperture is the first specification mentioned. The larger the aperture, the more light the scope takes in, and the better quality the image, but also the bigger and heavier the scope.

Magnification

You can change the magnifying power of a scope by putting in a different eyepiece. A zoom eyepiece lets you dial the power you want. The new, rather expensive zoom, eyepieces in high-end scopes offer excellent optical quality and are a good choice for birding.

Eye Relief

Long eye relief lets you see the whole picture even if your glasses hold your eye away from the eyepiece. If you wear glasses, eye relief is one of the most important considerations in choosing a scope/eyepiece combination.

Chromatic Aberration

When light passes through glass at an angle, its path bends. This law of nature enables a lens to focus an image. However, each color of light bends to a different degree, as you can see when a prism spreads a rainbow on a wall. In an image focused by a single glass lens, only one color is truly sharp; the others are slightly out of focus. This effect is called chromatic aberration. Telescopes use compound lenses made of different kinds of glass to try to cancel out chromatic aberration, and bring the colors into focus at the same point.

To further reduce chromatic aberration, some lenses use special materials, such as fluorite crystal or ED glass, because they disperse the colors less than regular glass. Such lenses can produce sharper images at high magnification, but they cost more, sometimes doubling the scope's price.

A scope that uses a mirror instead of a lens to focus the image, such as the Questar, escapes the problem of chromatic aberration, because the light is not refracted through glass.

Angled or Straight?

You can often choose between two scope styles -- straight-through or 45-degree angle eyepiece. It's a personal choice, but we think the angled scopes have the advantage for birding. Here's why:

1. Most angled scopes can be rotated in their mounts, allowing variable viewing angles. They make it easier to look up without bending your neck.
2. They can be mounted lower and therefore produce a steadier, better image.
3. They work with shorter, lighter tripods.
4. They let people of different heights see a bird without moving the scope.
5. They have a larger arc of use. For example, on a car window mount, they let you see farther ahead and behind the car.

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Types of Scopes

Birding scopes fall into two general groups: dedicated birding scopes and astronomical scopes that have been adapted for terrestrial or birding use.

Rugged and well sealed against water, dust, and weather, dedicated birding scopes are designed for heavy field use. Many are waterproof, with their focus mechanism and prisms protected inside the scope body.

Astronomical scopes often have their erecting prisms and focusing mechanisms outside the scope body, allowing you to customize the back end. Instead of using prisms, as most birding scopes do, with the inevitable loss of brightness and resolution that results when light passes through the prisms, you can replace the prisms with a 90-degree diagonal mirror and get better image quality. The eyepiece will then look down at a 90-degree angle into the scope. The picture will be right side up but reversed left to right. Note that astronomical telescopes tend to be somewhat fragile, and they need to be protected from the elements.

What Makes a Good Birding Scope?

Optical excellence. We all love bright, high-contrast images with true-to-life colors. Birders also appreciate rugged construction and optics well sealed from dust and weather -- preferably nitrogen filled so they won't fog up.

Usability is equally important. A birding scope shouldn't be too heavy to carry. It should be easy to focus and usable on a car window mount. Built-in, slide-out sunshades and easy-to-use lens caps help a lot.

Last but not least, a birding scope needs a good aiming device to help you find a bird quickly. When evaluating scopes, you're sure to run into the following terms. Study up before you start your research.

Optical Resolution Tests

We tested scopes that have zoom eyepieces whenever possible, because zooms tend to be popular with birders. For the smaller scopes, we tested at 20x and 40x, and the large scopes at 20x, 40x, and 60x. If only a fixed eyepiece was available, the scores of those tests include an "F" in the chart.

Note: These results show the combined optical quality of both the scope and the zoom eyepiece. Fixed eyepieces undoubtedly would have produced different results. Also, we tested only one sample of each scope, and it might have been atypical.

We tested all the scopes at the same distance and under similar lighting conditions. The resolution test chart we used had progressively smaller groups of lines. To the smallest group we assigned a score of 20; the next larger group 19, then 18, and so on. The difference in resolution between two consecutive scores was small but perceptible.

Much of the time birders use scopes at 20x, and you'll notice that at 20x most of the test scores don't vary a great deal. We were impressed at the high quality of the scopes we tested. In choosing your scope, the ergonomic qualities, such as size, weight, and focusing method, might outweigh a small difference in optical quality.

We have ordered the scopes below in two groups, the large and the small scopes, each roughly according to the resolution test results.

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Large Scopes (77--89mm)

Large Scopes

Questar Field Model 3.5 and Questar Birder 3.5 Tele Vue Ranger ED 70mm Swarovski AT80-HD High Definition scope 80mm Leica APO-Televid 77mm Fujinon Super 80 Fieldscope 80mm Nikon Fieldscope ED 78mm Pentax PF-80 ED 80mm Bausch & Lomb Elite ED 80mm Kowa Prominar TSN-823 82mm Deutsche Optik Optolyth TBG GA/HD Scope 80mm Swift 849 Nighthawk 80mm Brandon Master Birding Scope 80mm

Questar Field Model 3.5 and Questar Birder 3.5

In our resolution tests the Questar surpassed everything else. Questar focuses the image with a mirror instead of a lens, thus avoiding chromatic aberration and producing razor-sharp images and especially vivid colors. Furthermore, the compactness of design reduces vibration.

You look down at a 90-degree angle into the eyepiece. Two levers on the back of the scope let you switch among three levels of magnification. With a 32mm eyepiece on the Questar Field Model, you get 3x, 40x, and 60x. The 3x functions as a wide-angle finder.

Center what you want to see, flip the lever to increase the magnification, and focus. There's your bird, in stunning clarity. The 32mm eyepiece has enormous eye relief (more than 60mm) even at 60x, so this scope is a boon to eyeglass wearers. A variety of other eyepieces are available.

Two models of Questar are appropriate for birding, the Questar Field Model 3.5 and the Questar Birder 3.5. With the Questar Birder, the 3x finder is modified to 8.5x, and the focusing is 21/2 times as fast. The rapid focus modification is optional on the Field Model. Options for both models include broad-band and low reflection coatings, to increase light transmission 22 percent and improve contrast, and the Zerodur mirror, more thermally stable than the standard Pyrex.

The higher-power finder in the Birder model prevents the scope from rotating in its mount. However, the Field Model rotates and allows viewing from more comfortable angles. For birding we recommend the Field Model 3.5 with the broad-band coatings, the rapid focus modification, and the 32mm eyepiece. If you bird in a cold climate, add the Zerodur mirror.

The Questar is not designed for rough service, as are the specialized birding scopes. It's not waterproof, and it needs protection from weather and dust.

The Questar produces an image that is reversed left to right, because it does not use erecting prisms to flip the image into the normal position. Some birders do not mind the reversal or get used to it for the sake of the outstanding sharpness of this scope.

Tele Vue Ranger ED 70mm

The Tele Vue Ranger is a small astronomical telescope designed for birders. The scope's astronomical heritage shows in the way the whole eyepiece assembly slides out for a large range of focusing. You fine-focus with a cylindrical focus ring.

This kind of telescope lets you use a huge variety of eyepieces and really build your own system. For example, you can use a straight-through eyepiece, a 45-degree angled eyepiece, or a 90-degree angled eyepiece. When we tested the Tele Vue Ranger with a 90-degree diagonal (see Types of Scopes, above), the scope earned one of the highest resolution scores of any scope tested. It made a bright, beautiful (though reversed) image, even in dim light.

The Tele Vue Qwik-Point, at top left of the barrel, provides quick and accurate sighting. You switch on a battery-powered red dot in the sight and superimpose the dot on your target. A long mounting bracket for the tripod lets you slide the scope back and forth, varying the balance point.

The Ranger is not weather sealed like scopes that focus internally and have all their elements isolated from the environment. But if you want outstanding optical quality and great flexibility at a moderate price, take a look at the Tele Vue Ranger.

Swarovski AT80-HD High Definition scope 80mm

Superbly sharp from center to edge, this 80mm scope was the favorite of several of our judges. We could detect no color fringing or halo effect, even looking with high magnification at thin black branches against a bright sky, a situation that caused most of the scopes in our trials to demonstrate halos of varying colors.

Although this is a full-sized scope, with an objective lens slightly larger than the Leica Televid-77, the Swarovski is relatively lightweight. Excellent engineering and ergonomic design make it feel nimble and graceful in the hand.

The high-quality 20--60x zoom eyepiece offers excellent eye relief for eyeglass wearers. The zoom and other bayonet-mount eyepieces attach easily and neatly with a twist. The scope is well sealed and waterproof.

With no other scope we tested was it faster to find a bird and bring it into focus. Sights on top of the sunshade make aiming easy. Lay your hand on top of the scope, and your palm falls on the focus mechanism, a ribbed band that extends all the way around the barrel. Focusing is smooth and silky. The same hand that's swinging the scope into position is already focusing, and you can focus even wearing heavy gloves.

Leica APO-Televid 77mm

The Leica scope goes beyond bright--it's brilliant, and it has incredibly sharp focusing ability from center to edge. Even at high magnification, the image is remarkably free from color fringing.

Interchangeable bayonet-mount eyepieces attach with a quick twist. Our judges particularly admired the high-quality zoom, which has excellent eye relief for eyeglass wearers. Its twist-up eyecup lets you set the amount of eye relief you require.

The scope is waterproof. On the built-in lens hood, small post-and-notch sighting bumps let you line up on your target accurately. The Leica Televid is unique in having two focus knobs, one for fast and the other for fine focus. The only complaints about this scope came from two judges who found the fast focus wheel a little stiff and hard to turn.

Ruggedly constructed and finely engineered, this scope is beautiful to look at as well as through. It was one of the judges' favorites.

Fujinon Super 80 Fieldscope 80mm

This 80mm straight-through scope comes in a standard and ED-glass version, but no angled version is available. It comes with a 20--60x zoom. Fixed eyepieces are also available. It's sturdy, lightweight, and waterproof. There's a pull-out sunshade. A hollow tube sight on top helps you get on the target quickly. The focus knob, at the top of the barrel, is fairly small but focuses smoothly. A nice feature is the rigid screw-on lens cap that protects the entire eyepiece assembly. It's waterproof provided an eyepiece is attached. It turned in a fine optical performance, especially considering that the Fujinon model we tested did not have the ED glass.

Nikon Fieldscope ED 78mm

Nikon's 78mm Fieldscope rated highly with our judges for sturdy, intelligent construction. You'll never fumble for the focus ring. Nearly as broad as your hand, it extends all the way around the scope. It turns smoothly and offers just-right resistance. However, there is no sighting device or built-in sunshade, and the scope is not waterproof. Birders who wear glasses may find the eye relief of the 25--56x zoom not quite sufficient, so it's a good idea to try it before you buy it.

Pentax PF-80 ED 80mm

Pentax created this new, waterproof, straight-through 80mm scope to take advantage of the time- honored 11/4'' Pentax telescope eyepieces. You can get six interchangeable fixed eyepieces, originally designed for astronomy and low-light viewing conditions, and a 20--60x zoom. The scope body is waterproof even without the eyepiece attached. Remarkably, the Pentax zoom eyepiece itself is also waterproof.

The Pentax zoom has extra-long eye relief (20mm). The ring that changes the zoom's magnification is broad and unusually easy to turn. As with the Leica scope, you twist the front of the eyepiece to dial up the precise amount of eye relief that fits you and your eyeglasses.

Pleasant rubber housing covers the magnesium-alloy frame of the straight-through scope. There's an extendable sunshade and a sight on top to help you aim. The focus wheel, at top right of the prism housing, turns smoothly.

Bausch & Lomb Elite ED 80mm

Bausch & Lomb's straight-through scope comes with ED glass and a 20--60x zoom lens included in the price. The scope is partially rubber armored, with a slide-out sunshade; a big, useful aiming sight on the top; and a relatively small focus knob on the top right of the prism. It's well sealed, and it's waterproof with the eyepiece attached. It does not come in an angled version.

Kowa Prominar TSN-823 82mm

This is Kowa's top-of-the-line spotting scope. They've increased the size of the objective lens to 82mm (from 77mm), thus increasing light transmission by 13 percent. The scope has a peep sight on its right side and a pull-out sunshade. It's well sealed and waterproof, with a high-impact polycarbonate body. A hard screw-on lens cap protects the whole eyepiece assembly. The lens cap screws on also, so the scope is suitable for carrying around.

The 20--60x zoom eyepiece has good eye relief for eyeglass wearers, at least at 20x.

Deutsche Optik Optolyth TBG GA/HD Scope 80mm

This Optolyth scope sports a rugged, completely rubber-armored, sage green body. The scope is shock resistant, waterproof, and nitrogen purged. It has an extendible sunshade shield. The focus wheel, at top center, is smooth and silky.

We tested the straight-through model. The TBS 80 is the angled version. You can get six interchangeable eyepieces, including a 20--60x zoom, all of which also work with the 60mm scope.

Swift 849 Nighthawk 80mm

Swift built this 80mm scope primarily for bird watchers. It comes in straight-through and angled versions, with or without the special ED glass. It's partially rubber armored and has a slide-out sunshade. The color is a handsome gray and charcoal. The Nighthawk has a small focus knob at the top right of the prism housing. The aiming device is a small optical finder, like a miniature telescope, at the upper left side of the prism housing. We tested the scope with the 20--60x zoom eyepiece (849 Super ZE). In addition, five fixed eyepieces are available.

Brandon Master Birding Scope 80mm

This sturdy, well-armored 80mm astronomical scope by Vernon Scope & Company has easy-to-locate focus knobs on each side. It can take huge, 2-inch diameter eyepieces. The 2-inch, 30mm-wide eyepiece has long eye relief and is remarkably easy and relaxing to look through. We did not give this scope a resolution score, because with the 30mm eyepiece it provides only 15x, but it does provide a bright, wide-angle view. If you move your head slightly, foreground objects move against the background, making the picture look 3D. Minimum focusing distance is a mere eight feet. The scope comes with your choice of the 30mm eyepiece or a 15--50x zoom.

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SMALL SCOPES (50--60mm)

Small Scopes

Bushnell Spacemaster 50mm Fujinon Super 60-S Fieldscope Kowa Prominar TS-614 60mm Deutsche Optik Optolyth TBG 65 GA Nikon 60mm ED Angle Fieldscope III Swift 844 Panther 60mm Swift 839 Searcher 60mm Eagle Optics Raven 60mm

Bushnell Spacemaster 50mm

The venerable classic spotting scope for years was the 60mm Bushnell Spacemaster. For our tests Bushnell sent us their compact 50mm Spacemaster. This straight-through scope comes with a 10--30x zoom. A 15--45x and 20--45x zoom are also available. Rugged looking, black rubber armored, it has a peep sight on top; the focus is on the eyepiece. The judges were impressed by the remarkable optical quality for the size and price of this scope.

Fujinon Super 60-S Fieldscope

The 60mm Fieldscope is available only with the standard (non-ED) glass. This scope looks like a miniature of the 80mm straight-through scope. It comes with the same 20--60x zoom and uses the same lenses. In addition to the bayonet mount, the zoom lens has a screw-on lock for extra security. The scope is waterproof and nitrogen purged.

Kowa Prominar TS-614 60mm

This small scope is gray-green, with a built-in retractable sunshade and partial rubber armoring. It's well sealed, waterproof, and lightweight, with a smooth focus. A rigid screw-on cap protects the interchangeable bayonet-mount eyepieces.

The scope has excellent optical qualities. Although a 20--60x zoom is available, we had only the fixed 27x to test, which makes its score hard to compare. However, when we tested other 60mm scopes with zooms at approximately 27x, this Kowa scored similarly to Nikon and Optolyth.

Deutsche Optik Optolyth TBG 65 GA

The straight-through model we tested has a wide, easy-to-locate focus ring that encircles the entire barrel. It's also available in a 45-degree angled body. It's rubber armored, nitrogen purged, and waterproof even with no eyepiece attached. It takes interchangeable screw-in eyepieces.

Nikon 60mm ED Angle Fieldscope III

This is a sweet little scope, the absolute favorite of one of our judges. It's compact, well sealed, waterproof, and nitrogen purged, with a pull-out sunshade and broad, rubberized, easy-to-find focus ring. There are sighting lines on the right side of the prism housing.

Nikon's small 20--45x zoom eyepiece turns smoothly and contributes to the compactness of the 60mm scope. If you want to backpack with a spotting scope, you could hardly do better than to carry this rugged, well-made little scope.

Swift 844 Panther 60mm

This straight-through scope is sleek, compact, and black like a panther. It weighs less than two pounds. You can get a 20--60x zoom eyepiece (844 Super ZE) for it, as well as fixed eyepieces (15x, 20x, and 40x). A rigid screw-on lens cap protects the entire eyepiece assembly. The focus wheel lies flat against the right side of the scope.

Swift 839 Searcher 60mm

An unusual feature of this 60mm scope is the rotating head, which contains two eyepieces and allows a choice of straight viewing at 20x or angled viewing at 40x. You can purchase a close focusing lens (839CLF) that brings the focus from 30 feet down to 15 feet.

The all-black scope is completely rubber armored. The focusing band goes around the entire barrel.

Eagle Optics Raven 60mm

This light, slim little scope would be a good traveling companion. There's no sighting device, but it's easy to aim by simply pointing the straight-through barrel at your quarry. The Raven is armored with a pleasant black rubberized material. It comes with a built-in 15--45x zoom, and the focus wheel is on the eyepiece.

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