Choosing the right binocular for birding can be a confusing task that makes you want to just close your browser and forget about it. To try and make the task a little easier I’m going to try and explain what most of the jargon is behind all those product pages and explain it in real terms. After that, hopefully it will help get some new binoculars in your hand and out there seeing feathers up close. 

It seems every company has a marketing term for their glass and often it doesn’t cross over to another company’s terms. This makes it difficult for the consumer to make an apples-to-apples comparison. Is ‘HD’ glass the same as ‘DX’? Hard to say.

One glass designation does seem to carry weight across all brands though, and it’s Extra Low-Dispersion Glass, or ‘ED’. If a binocular says it has that, it can be assumed it truly has that type of glass. But what is it? Simply put, it’s glass that acts like a filter to correct or reduce if not remove something called chromatic aberration.

Chromatic aberration is something you see usually while viewing a high-contrast image such as a dark crow against a bright overcast sky in the background. It’ll present itself usually as a purple, green or magenta fringe around where the two contrasts meet. This is an undesirable effect that takes away from a great viewing experience. ED Prime glass is certainly a must-have if you want to maximize your resolution while not having color artifacts while on the birding trail. 

There are a lot of different coatings out there. Some are referred to in general terms while others are referred to by manufacturers by a proprietary name. They don’t all do the same things, either. Some change what light waves are allowed through or how they’re allowed through. Some increase light transmission – Think of it like making a dirty windshield totally wet, the light gets through brighter. Others do things like repel stuff like water.

When looking through the coating and specifications you’ll almost always see something about ‘fully coated’ or ‘fully multi-coated’ or something similar. Here’s what those things mean:

• Coated: A single layer on at least one lens surface.
• Fully Coated: A single layer on all air-to-glass surfaces.
• Multi-Coated: Fully Coated plus multiple layers on at least one other lens surface.
• Fully Multi-Coated: Multiple layers on all air-to-glass surfaces.

What’s all that mean? The more the glass is coated the better. So expect to see the prices go up as a specification changes down the line. Fully Multi-Coated is best here. It’ll give you the best light transmission and usually color and contrast.

How about proprietary names? In Bushnell’s case there’s two that come to mind which are the ‘Dawn & Dusk’ coating and the ‘Ultra Wide Band’ Coating. They’re essentially doing the same thing but the Ultra Wide Band is the newest and best version. What is it they do? They act like filters where they let through certain light waves but stop others. An example of why you’d want this is the lens flare. You’ve all seen it, it’s that really bright and vision obscuring flare of light that appears on glass and makes it so you can’t see. You can see an example of it in the image above with the green artifacts in the middle. Bushnell's Ultra Wide Band reduces and sometimes eliminates that flare making it so you can see something when ordinarily you couldn’t.

Another type of proprietary lens coating you might hear or see is one that’s oleophobic and/or hydrophobic. This coating acts like a non-stick for you glass on the outside so water and oil shed off during use so you can still see, and make it so you don’t have to clean the glass as much, and when you do it’s easier to clean. An example of this would be Bushnell’s RainGuard or EXO Barrier coatings. They’re good stuff. 

Prism coatings are a little easier than lens coatings as far as how many there are. You have two essential ones, if the binocular you’re looking at even has them. For the sake of this article being about birding, I’m going to only refer to roof prism binoculars.

Roof prisms require the use of a reflective coating that act like mirrors reflecting the image as it passes through prism. Better coatings means better mirrors and a better and brighter image. Cheaper binoculars will often use an aluminum coating to accomplish this. A premium coating is called dielectric. This coating serves to increase light transmission by being more reflective than the cheaper aluminum coating. For birding in lower light you’ll want to make sure the binoculars in your hand have dielectric coating.

The second type of prism coating is the one that corrects the phase of the light waves as they pass through the prism and exit it. In other words, it helps align the image correctly as it exits the prism. This can increase resolution greatly. For Bushnell, PC3 Phase Coating is the coating that accomplishes this and it’s found in our premium binoculars. If you want the sharpest images and to see those birds the best, you’ll want to make sure the binoculars you’re getting have phase coating.

Ever look through a paper towel tube? It gives you tunnel vision. Some binoculars can feel like tunnel vision if they don’t have a great field of view.

Optics companies publish their field of view (FOV) almost always in feet at the distance of 1000 yards. For example, our Engage EDX 8x42 have a field of view of 426 feet. That means if you’re viewing a scene from 1000 yards away, you’ll have a left to right viewable distance of 426 feet. If you compare that to another binocular that has only say, 396 feet, or in this case 30 feet less than the Engage EDX 8x42’s, then you’ll be giving up useable image. The image above will give you an idea of what that looks like and what you’re giving up.

Another issue that comes up with field of view is the usability of them when it comes to trying to find the bird in the binoculars, and it’s especially true when they’re in flight. A wider field of view gives you more margin of error to find them and get trained on them. Something to consider also is that the higher the magnification the narrower your field of view will generally be. So, when you’re shopping for birding binoculars, don’t forget to compare the field of view specifications. Also, a higher magnification is harder to hold steady so the image is more likely to shake and almost act out-of-focus.

Chassis is another word for the body of the binocular, and it’s going to be made of different materials. These different materials have advantages and disadvantages.

Some chassis are made of a polymer (think plastic) or composite while a metal chassis will usually be made of an aluminum or magnesium alloy. Magnesium is light, strong, and expensive. Aluminum is light but not as light as magnesium and it costs less than magnesium but more than composites.

Many binoculars have a chassis made of a composite material. That material is usually a simple polymer with glass fiber reinforcement. Two big advantages of a composite chassis are the low weight and a significantly lower cost than a metal chassis.

The weight issue for birding can be twofold. On one hand, extra weight can help with stability. On the other it can increase fatigue, especially if you’re planning on holding them up for long periods of time. While metal can be more rugged and be less susceptible to issues from heat or cold, it does come at the cost of higher weight. If you do go with metal, you’ll want to make sure it’s magnesium for the high strength yet light weight. 

Now that you’ve hopefully got a handle on what all the specs and lingo in binocular shopping means you’ll be able to make some good apples to apples comparisons while narrowing down your search. A checklist based on your needs could also be useful. Here are must-have features if you wanted the best optical features to check off while also determining which has the best weight, field of view, and a cost you are comfortable with.

1. ED Prime Glass
2. Dielectric Coating
3. Prism Phase Coating
4. Wide Field of View
5. Acceptable Weight
6. Cost You're Comfortable With

In the world of binoculars there are a lot of choices. It can be confusing. The more you can see them compared with the same terminology and understanding of what your needs are the less confusing it’ll be. Hopefully this post helps answer some questions and guide people to an informed decision about their next set of birding binoculars and one they can feel confident about. 

If you’re looking for a personal recommendation from me on this, I’ll make it simple. Check out the Engage EDX 8x42. They check all the boxes on the best features optically and on the chassis while being lightweight and having a great field of view. They won’t break the bank either.

-         Bushnell Social Guy