Seeing is believing. However, how well you see may depend on more than your vision. When your path passes through uncertain surroundings, you may need a closer look. If a vehicle or boat is approaching your location, you need to know whether it is friendly or otherwise. Exactly what is that animal on the hillside along your route or what is that noisy bird? In some cases human vision is sufficient, but in many others it is not. A compact binocular may be what you need.
In former days, binoculars tended to be like the military surplus model my brother borrowed from his biology teacher in the 1950s. That binocular (singular form of an optical device for use with two eyes) was a large, heavy 7X50 Bausch & Lomb, but you sure could see craters on the moon with it because it was bright and sharp. For many years thereafter, commercial binoculars tended to be of that type, but that has changed dramatically. Currently, there are numerous compact models that are both bright and sharp.
For this review, I selected three current compact binoculars I have used extensively. They are the Leupold Rogue, Nikon Travelite VI, and Olympus Tracker PCI, all of which are 8X25 models, so they have the same exit pupil diameter. Having decided which models to test, they were obtained quickly from B&H Photo and Adorama, two of the large suppliers of cameras and other optical equipment. Current prices of the Nikon and Olympus at B&H are $79.95 and $59.99, respectively. Adorama lists the Leupold for $84.95 with free shipping. All three units were delivered within three days.
All of the binoculars have a central focusing knob and the right hand eyepiece can be focused individually to compensate for any difference in vision between left and right eyes. Each binocular has a focusing dial around the right hand eyepiece with some sort of markings that can be positioned in reference to an index mark on the frame of the binocular. Correctly focusing a binocular is done by selecting an object at some distance and focusing on the object while looking through the left eyepiece using the center focusing knob. Focusing is completed by means of the right eyepiece so that each eyepiece is focused individually for that eye. To facilitate use by persons who wear glasses, the Leupold and Olympus have twist up eyecups but the Nikon has rubber eyecups that can be folded to adjust the length.
A target was used to test sharpness with each binocular mounted on a tripod. After accurately focusing the binocular, I proceeded to examine the rings and fine print on the target. Next, the head of the tripod was rotated so the edge of the view was directed toward details on the target in order to detect any difference between center and edge sharpness.
Optical devices such as cameras and binoculars are subject to two types of distortion. One type is known as barrel distortion, which causes straight lines to appear to bow outward away from the center of the field of view. The opposite type of distortion, known as pincushion distortion, gives lines that appear to bow inward toward the center of the field of view. By examining a brick wall with the binocular supported on a steady rest, it is easy to detect either type of distortion if it is very noticeable.
As a result of having a waterproof, rubbery coating, the Leupold Rogue is the largest and heaviest of the models tested. It weighs 12.7 ounces and measures 4.6 inches in length. Although I did not perform shock tests, it is very likely the most durable of the three. To my eyes, the image seen appeared to have a slightly softer appearance. However, the Rogue is easy to focus as a result of having a comfortable knob that requires substantial turning to focus. Some compact binoculars are designed so that when the focusing knob is turned very little, the focus changes greatly. The image seen appears to be slightly softer and have less contrast than either the Olympus or Nikon.
Nikon Travelite VI
The Nikon Travelite VI is the latest incarnation of the series that has gone from Travelite to the VI version. Although is measures 4.5 inches in length, it weighs only 9.4 ounces, the lightest of three models tested. The image seen through the Nikon has a bright, crisp appearance with pleasing contrast. In terms of center sharpness, the Nikon appears to have an edge over the Olympus and Leupold.
Olympus Tracker PC I
Long known for excellence in small optical devices, the Olympus Tracker PC I continues that tradition. As a result, it is a small binocular that measures only 3.8 inches in length and weighs 9.9 ounces. The Tracker appears to have a very bright view that snaps into focus easily. It focuses as close as 8.2 feet making it suitable for close viewing of small birds and animals.
“With both the Nikon and Olympus, the image at the inside edge of the field appeared sharper than at the outside edge.”
None of the binoculars show any detectable barrel or pincushion distortion. To my eyes, it appeared the Nikon and Olympus models gave a slightly brighter image than the Leupold, even though all of the models have the same value for the relative brightness. This may be caused by different coatings used on the lenses or prisms. However, when testing edge sharpness, it appeared the Leupold was slightly sharper at the edge than either the Nikon or Olympus. Moreover, with both the Nikon and Olympus, the image at the inside edge of the field appeared sharper than at the outside edge. When looking at a bucket at a construction site, all three made it possible to read the label on the bucket when it was in the center of the field. Except for critical viewing, edge sharpness is not much of an issue because the viewer naturally places the object of interest in the center of the field.
I have used an old Nikon Travelite II for many years so I expected the VI version to be good, and it is. However, the optical performance of all three of the binoculars exceeded my expectations. They are high quality products from three major manufacturers and any of them would be excellent for general use. Having said that, I must say it is the Olympus Tracker PC I that is in my camera bag most of the time.
Binoculars are characterized by two numbers. For example, a 7X50 binocular has a magnification of seven and 50mm objective lenses. A 6X30 model magnifies the image by six and has 30mm objective lenses. Another important parameter describing a binocular is known as the exit pupil, which determines the apparent brightness of the image. The exit pupil is essentially the diameter of the light path coming through the binocular to the eye.
The size of the exit pupil is found by dividing the diameter of the objective lens by the magnification, and relative brightness is the square of the exit pupil size. For example, a 7X35 binocular has an exit pupil of 35 divided by 7, which means the exit pupil is 5mm in diameter and the relative brightness is 25. This is the same as in the case of a 6X30 binocular because 30mm divided by 6 is also 5mm and the relative brightness is 25. For a 7X50 binocular, the exit pupil is 50 divided by 7, which is approximately 7.1mm corresponding to a relative brightness of 50, indicating a very bright view. In fact, the brightness of a 7X50 binocular is twice that of a 7X35 model. That is one reason why many military binoculars have been 7X50 models. The field of view is the width of the area seen at 1,000 yards and usually about 350 too 400 feet.
Much has changed over the years with all types of optical devices. The light entering the objective lenses is directed to the eyepieces by reflection from the surfaces of coated prisms. The lenses themselves, as well as the prisms have coatings that maximize the amount of reflected light with the result that some modern compact binoculars having designations such as 8X25 give a very bright view even though the exit pupil is only 3.125 mm and the relative brightness is 9.8. Moreover, some models weigh only about half a pound.
|Olympus Tracker PC1||Leupold Rogue||Nikon Travelite VI|
|Durability||Rubberized||Plastic housing||Plastic housing|
|Waterproof||Yes||Plastic housing||Plastic housing|
|Pleasing view||Sharpest edge||Best overall||Good|
|Weight, oz.||Heaviest, 12.4||Lightest, 9.4||Light, 9.9|
|Glasses provision||Twist up cups||Flexible cups||Twist up cups|
After a 32-year career as a chemistry professor at Illinois State University, Jim House has written extensively about shooting sports, which has resulted in the books American Air Rifles,CO2 Pistols and Rifles, The Gun Digest Book of 22 Rimfire and, with his wife Kathleen,Customize the Ruger 10/22. Jim is the Reloading Editor for Gun World and a Contributing Editor for other magazines.
Editor’s note: A version of this article first appeared in the May 2015 print issue of American Survival Guide.