North American Butterfly Association

Zebra Swallowtail

Binoculars for Butterflying - 2001

by Gary Fellers

Though butterflies can be enjoyed without any special equipment, a good pair of binoculars can enhance your ability to see subtle features of their color, structure, or behavior. In this article, I discuss binoculars for butterflying and review 17 models of binoculars that you might consider purchasing. The binoculars reviewed here can focus to within at least 8 feet, with most focusing well inside 6 feet. A PDF table listing the features discussed below is available for downloading.

   A bit of individual preference is involved when selecting binoculars, so I assembled a panel of eight people to help. The panel members ranged in age from 15 to 60 years and their experience with binoculars ran from modest to extensive. Each person evaluated binoculars using a series of test charts, mounted insects, and special lighting situations. After a few hours, we compared notes and eliminated some binoculars from further consideration. We then reevaluated the best models. Throughout the day, everyone shared thoughts on their likes and dislikes. The recommendations that follow are based upon a general consensus.

   Some characteristics are difficult to evaluate. Durability under field conditions is an important factor, yet one we could not address. Some people use binoculars only under fairly mild conditions and always store their binoculars in the case. Others use binoculars under rather arduous field conditions and sometimes end up stuffing them in a pack without the case. Some binoculars might seriously deteriorate or completely fail with hard use. Only time will tell whether the less expensive binoculars will last given your specific pattern of use.

Binoculars are described using terms such as 7 x 36 or 10 x 42. The first number refers to the power, or magnification. Seven power binoculars will enlarge the image seven times larger than life-size. While it might seem like an advantage to have the image enlarged 10 times, there are some disadvantages. With higher magnification, it is much more difficult to find a butterfly quickly with the binoculars. The butterfly will take up more of the field of view (which is good), but there will be less of the surrounding bush, puddle, or flower. The background often provides the visual cues useful in recognizing where you are looking, allowing you to locate the butterfly easily.

   Some species of butterflies have erratic flight patterns. Trying to follow these butterflies with 8 - 10 x binoculars can be a difficult and frustrating experience. The larger image and smaller field of view means that the butterfly must be tracked more accurately to keep it in sight. Even when watching stationary butterflies, small movements of your hands or body are magnified by the binoculars so it is more difficult to hold a steady image.

   Lower power binoculars (7 x) are good for butterflying since many species can be closely approached. Lower power binoculars are often smaller and more compact, the field of view is larger and they are easier to hold still. The image, however, is magnified less.

Objective Size
The second number in a term such as 7 x 36 refers to the diameter in millimeters (mm) of the objective lens — the end of the binoculars facing the butterfly. In general, the larger the objective, the more light is gathered and hence, the brighter the image. The quality of the lens also has a significant effect on brightness. Since butterflies are often seen in bright places, the objective size and light gathering ability will often not be of concern. However, if you expect to watch butterflies in wooded areas, light gathering characteristics becomes much more important. The disadvantage of a larger objective is that the lenses are larger, often making the binoculars heavier.

Close Focus
Since butterflies can often be observed at close range, the ideal binoculars will allow you to focus as close as your feet, and perhaps even closer. Only a few years ago, most binoculars could not focus within 10 feet, but fortunately this has changed. Unfortunately, the close focus ability of binoculars is often not included in product literature, and when it is, the numbers are often not accurate. I have measured the close focus for all the binoculars included in this review. These numbers will vary a bit from one person to another depending on your vision.

Eye Relief
Eye relief refers to the distance from the lens (ocular) to where the image is in focus. If you wear glasses, the eye relief must be at least 15 mm in order to see the entire image. If you are interested in the economically priced Pentax 8 x 24 UCF WR, note that the eye relief is only 13 mm.

Eye Cups
The rim around the ocular is rubber or rubber-coated so that the eye cups rest comfortably on your face. For those who wear glasses, the rubber helps keep the binoculars from sliding around. There are several types of eye cups. I prefer soft rubber ones that fold down for those who wear glasses. If you share binoculars with someone who wears glasses, these eye cups are somewhat less convenient, but I prefer the feel of soft rubber. The other types of eye cups are either pop-up or twist-up. The better ones move somewhat stiffly so that they do not collapse in use (a minor nuisance). Several of the panel members noted that some eye cups were rather hard and would almost certainly become uncomfortable with much use.

Waterproofing may not an issue if you only use your binoculars on nice days. For others, it is a welcome addition that means that you do not need to put away your optics when the weather deteriorates. Also, if you visit tropical areas, it is hard to keep binoculars dry no matter what you do. I ruined my first binoculars while studying Hawaiian birds in a driving rain. Since then, I’ve only owned waterproof binoculars. Waterproof binoculars are also easier to clean.

Lens Coatings
A lot could be said about lens coatings, but the simple answer is that more is better. The benefit of coatings is that the image is brighter and has truer color. Some people notice the difference in coatings while others do not, so you need to judge for yourself.

   In order of benefit, lenses can be coated, multicoated, or fully multicoated. There might also be an additional phase correction. You need to read the specifications carefully to discern what type of coating each binocular pair has. There is often a lot of hedging with statements like “some lenses are multicoated.” Also, note that the quality of coatings varies from one manufacturer to another.

Exit Pupil
Exit pupil is the size of an image exiting the binoculars. In bright light, the pupil in the human eye closes down to about 2 - 3 mm, but in low light, it can open to 6 - 8 mm. If the pupil diameter is greater than the exit pupil, the binoculars are not providing as much light as could be used by the eye. Most binoculars work well in bright light, but only the better ones work well in dim light. Image brightness is not only determined by the exit pupil; it is also strongly influenced by the quality of the lenses and the lens coatings.

Ease of Focusing
There are two important aspects of focusing: the stiffness of the focus wheel and the number of full rotations of the wheel to change from close to distant focus. I prefer something in the range of 1/2 rotations, but others prefer more or less. The Pentax 8 x 24 UCF WR were notable, requiring more than a full rotation while the Nikon 5 x 15 needed only 1/4 turn. The stiffness of the focus wheel is a personal preference. I like an easily moved wheel, but others prefer a firmer feel.

Small Binoculars
The Nikon 5 x 15 and 7 x 15 Titanium binoculars are like nothing else we reviewed, though there are other, similar binoculars on the market. The Nikons are very small, lightweight, and focus remarkably close. They are almost awkwardly small; my last finger has nowhere to perch. The 5 x model has a nice, bright image, but it only magnifies 5 times, which is not really enough if there are subtle details to study or if a butterfly is not quite close. The 15 mm objective is rather small, leaving the 7 x model with an exit pupil of only 2.1. This results in a darker image in low light conditions. The panel’s consensus was that the brighter 5 x image was more useful than the darker 7 x image, especially in dim light.

   While the cuteness factor of these small Nikons appealed to some folks, others did not like the binoculars at all. There was a strong dichotomy of opinions about whether these binoculars were wonderfully convenient, or an expensive toy. Make sure to see these in person if you think you might buy them.

Zoom Binoculars
The two zoom binoculars are examples of a good concept that has been poorly implemented. The Pentax FB Zoom is a small box-shaped pair of binoculars that functions poorly in almost every regard. No one on the panel liked them, even marginally. The image is poor at 6 x and gets worse (and darker) at higher magnifications. If you want pocket-sized binoculars, the Nikon 5 x 15 Titanium is much superior.

   The Pentax 8 - 20 x 24 UCF Zoom is the better of the two zoom models, but the fixed power Pentax 8 x 24 UCF WR are much better at roughly 2/3 the price. The 24 mm objective on the zoom model is satisfactory at 8 x, but at 20 x, the exit pupil is only 1.2 mm, resulting in a very dim image. If you need the higher magnification, you would be better off with one of the 8 x or 10 x binoculars.

Seven and Eight Power Binoculars
We evaluated nine pairs of binoculars in the 7 - 8 power class. The clear favorite was the Eagle Optics 8 x 42 Ranger PC. This is a comfortable, well-balanced pair of binoculars that has a good bright image. I prefer it to the somewhat closer focusing EO 7 x 36 Rangers. Perhaps the phase coating on the 8 x makes the difference. The Swift 7 x 36 Eaglet is also a very nice binocular pair that is essentially the same as the 7 power Rangers. I would be inclined to pay the small difference in price for the additional lens coatings and marginally better image of the Ranger PCs. The Pentax 8 x 32 DCF WP were good, but ranked behind the EO and Swift binoculars.

   Several years ago, the B&L 7 x 26 Customs were notable in their close focus ability. They have now been surpassed, but considering their price and compactness, you might decide that the 8’ close focus is adequate. For the money, the Pentax 8 x 24 UCF WR are a good deal. They do not perform as well as the other binoculars in this group, but they only cost about 1/3 as much. If you are on a tight budget or only need binoculars occasionally, these might be the binoculars for you.

   The Steiners were quite good, but not competitive for the price. They also had a rather dark image in low light. The Bushnell 8 x 42 were largely undistinguished and heavy, with relatively poor close focus. The Eagle Optics 8 x 32 Raptor PCs were optically nice and had good balance, but the focus was remarkably stiff and the focusing wheel had only low ridges to assist in turning. While a couple of the panel members liked the Raptors, most were put off by the focusing mechanism. I tried some additional cold weather tests and found that at 40o F, it required two fingers to move the focus wheel. Even on a warm day, these binoculars would be tiring to use.

Ten Power Binoculars
The favorite binoculars in the 10 x group were the Eagle Optics 10 x 42 Ranger PC. Weighing only slightly more than the similar Eagle Optics 8 x 42 Ranger PC, these binoculars had the same bright image and a comfortable, well-balanced feel.

   It’s hard not to like the Bausch & Lomb 10 x 42 Elite. For several years, they have set the standard for high quality and close focus ability in a full size binocular pair. But the Elites are not obviously better than the Eagle Optics 10 x 42, however, and the Elites are somewhat heavier, not to mention far more expensive. I like the way the Elite’s offset grooves allow your thumbs to fit around the barrels, but other panel members (with smaller hands) found the fit rather uncomfortable. The remarkably smooth twist-up eye cups are nice, but the design creates places for dirt and cookie crumbs to gather.

   The Pentax 10 x 42 rate just slightly below the Eagle Optics and Bausch & Lomb. The close focus is not quite as good and the focusing mechanism requires much more turning to adjust from near to far. The beefier barrels are also less comfortable than other binoculars in this group.

   The Swift 10 x 42 Viceroy may be named after a butterfly, but I cannot recommend them. At distances beyond 8’, they perform on par with the Swift Eaglet, but at closer distances the image becomes notably blurry. At first I thought I must have received defective binoculars, but I checked a second set and noted the same problem.

Final Thoughts
Being a field biologist, I have enjoyed having a wide selection of binoculars to choose from when conducting research these last few weeks. So, which did I select? With little hesitation, I went for the Eagle Optics 8 x 42 Ranger PC. They were great. Two of the other panel members were working with me, and they selected the 7 x 36 and the 10 x 42 Eagle Optics Rangers. At the end of the day, we compared notes and were all quite pleased. I might add that two of us normally use 10 x 42 B&L Elites that cost more than twice as much, so we are used to high quality optics. While I’m not yet ready to trade in my Elites, the Eagle Optics Rangers seemed to be a comparable choice for the type of work I do (observing frogs, sometimes at close range).

   What you might actually pay for binoculars is only casually related to the list price. In order to give a more accurate indication of cost, I have included a recently advertised price from one dealer. You are likely to find binoculars at both higher and lower prices, but this will provide a more useful comparison than do the list prices.

   There are some good sources of information on binoculars available on the Internet. One of the best is Eagle Optics has one of the most complete catalogs and price lists. It is available by calling 1-800-289-1132.

   I want the thank C. Corben, C. Fellers, J. Fellers, R. Fugate, L. Hug, P. Kleeman, and J. Markin who helped test the binoculars.

Copyright © 2001 by the North American Butterfly Association, Inc. All rights reserved.