The context

The problem with naturalists is that, beyond saving critically endangered species, they can agree on almost everything (which is not necessarily a good thing). By this, I mean that each naturalist has a passion, be it frogs or butterflies or moths or mammals. They will go along into the jungle for a ride, each carrying their binoculars. But in terms of agreeing about which trail to go to pursue what, man, there is as much cacophony as the jungle itself.

One wants to stay by the water hole and wait for animals; another wants to go into the dense forest where there is a dead tree with the most fascinating mushrooms growing on it. Add birders into the mix and the pendulum swings even more wildly. One is only interested in warblers; another want to spend four hours in hot pursuit of nightjars to add to their “life list”, and a third wants to search for quails. The question is: which pair of binoculars would suit all these characters?

The product

Alpen Optics’ Teton ED HD binoculars 10X42 is multi-coated with BAK4 glasses. In plain English, this means that they are pretty amazing binoculars for their price (which at $500 is in the lower end of the sports optics spectrum, but we will get to that).

First things first: what do those numbers mean? 8X42, 10X50, etc? The first number is magnification that comes from the ocular lenses near your eye. The 10 in the Teton means that it is magnified 10 times. The second number is the diameter in millimetres of the objective lens that is where the light comes in.

The larger the number, the more light it can gather up, and the heavier it is likely to become. For casual birders and nature-lovers, either an 8X42 or 10X50 should suffice. There is also the issue that the tremor of your hands will be visible at higher magnifications, which is why spotting scopes with excellent magnification are usually mounted on a tripod.

Like most good binoculars, the Teton is made with ED (Extra Low Dispersion) glass, which reduces the bleed of colour that occurs at the edges of the cheaper binoculars. This is called chromatic aberration. It is made from barium-crown glass which is a high-density glass (hence the HD in the name) with BaK-4 prisms, as opposed to the lower end models which use boro-silicate glass (BK-7)—yes, the same variety used in thermometers. BK-7 is a low density glass and therefore reduces the sharpness of images.

For naturalists, HD ED binoculars make the most sense, because you are looking for details of shape and markings. Multi-coated lenses such as the ones in the Teton are also de rigueur. Coatings are put on all the glass surfaces that touch the air to reduce glare and increase/improve the transmission of light. They can be of many different types, but typically multi-coated lenses choose the best coating for each surface.

Waterproof lenses are great for whale-watchers and those involved in nautical activities. Also for those of us who live in the tropics and have to worry about fungi growing inside and affecting the lens coatings of expensive binoculars. The Tetons are, yes, sealed and waterproof—no need to worry about moisture seeping inside these scopes. Like others in their class, are filled with nitrogen so that the interior doesn’t fog up. Today, argon-filled scopes tout their superiority to nitrogen but for periodic users these distinctions may as well be about the periodic table rather than reality.

Okay, that’s the jargon. How does it work?

As a user, I care about weight, magnification, and field of vision. In the lower grade binocular, one irritating factor is the blur that occurs at the edges of the lens. With these, the edges offered clear magnification even at 1,000ft. You could see a warbler or bulbul fly into a bottle-brush tree.

Weight is an issue especially if you are out in the wild for hours. These binoculars are light relatively to the magnification they offer. You can fit them into a shoulder-harness (recommended) and be out all day. You can even sling them across your shoulder and not experience aches. For those wearing spectacles, these binoculars offers a long “eye relief” which is an adjustment that the lenses have for eyeglasses. This makes it easy viewing through spectacles unlike the cheaper models where you have to take off your glasses to see well.

The difficulty I had was with the closures. I always cover my lenses after every use, having learned from previous instances where I left the binoculars open only to find them coated with dust. The Tetons’ twist-lock eye cups were onerous to use. They should have been designed to fall underneath the lens as you hold it up. Instead, these ones are designed to be connected in the center which means that you have to keep pulling the lens caps down through the middle.

These quibbles aside, I found these binoculars great for everyday use.

The details

https://www.alpenoptics.com/

The Alpen Teton retails for about $500 through multiple retailers.

The verdict

Given that good binoculars can easily start at over $1,000—the latest Zeiss Victory SF is priced at $2,899—this is an incredibly reasonable price for an excellent pair of binoculars. The “no-fault no-problem lifetime” warranty is only cream on top of what is a solid product.