<\/span><\/h2>\nIn this first part I explain some of the characters of binoculars. I explain the materials, construction and the specifications. I explain why these are important for bird watching.<\/p>\n
When researching your next pair of birding binoculars, make sure they meet these exacting standards and have these exact materials.<\/p>\n
The best binoculars are roof prism binoculars<\/h3>\n There are two styles of binoculars, porro prism and roof prism designs. Prisms flip the image right-side up for the viewer. Without prisms the view would be upside down and the barrels would be long like a telescope.<\/p>\n
The traditional style, common even today, are the porro prism binocular design. <\/b><\/h4>\n Porro prism binoculars use offset prisms and the body shows the easily-recognized zigzag shape.<\/p>\n
These are fairly easy to manufacture, so cost less, and are bright with good depth of field. That’s the good.<\/p>\n
On the down side, these binoculars can be knocked out of alignment easily if dropped. They are harder to make waterproof. They are often physically larger and bulkier.<\/p>\n
Roof prism binoculars have become more popular in the last couple of decades. <\/b><\/h4>\n
Roof prism binoculars are rather narrow and compact. The eyepieces are more in line with the objective lenses. They have a shape like the letter H.<\/p>\n
They are sturdy and the prisms stay in alignment. They are easier to make waterproof and fog proof.<\/p>\n
On the downside, roof prism binoculars are harder to manufacture. They need tighter tolerances to align both barrels to focus into one seamless view. The Schmidt-Pechan roof prism design requires special mirror coatings to prevent loss of light and transmit a bright image. All these things makes roof prism binoculars cost a bit more than corresponding porro prism binoculars.<\/p>\n
The demand by birders for these rugged and superior binoculars has caused manufacturers to improve their materials and technique. And the prices have fallen. Good news, indeed!<\/p>\n
The best general-purpose bird watching binoculars are 8x magnification<\/h3>\n I grew up on 7x porro prism binoculars. They have a wide field of view. Still, I wanted the birds to appear larger.<\/p>\n
So eventually I bought 10x porro prism binoculars. Birds appeared larger. But they were less bright. The field of view was narrow, so harder to immediately find a bird. And they were heavy to use in the field all day.<\/p>\n
When these wore out and the price for the waterproof roof prism binoculars came down, I bought 8x roof prism bins. I have stayed with this magnification ever since.<\/p>\n
It doesn’t matter whether you have porro or roof prism designs. 8x binoculars are brighter in low light conditions, have a wider field of view, have better eye relief, have closer focus, and are lighter than identical models of 10x binoculars. 8x are better in every way to 10x binoculars,… except for magnification.<\/b><\/p>\nWhen would you use 10x binoculars?<\/h4>\n
The stronger 10x binoculars would be better in open country. In bright sun you will not notice the difference in brightness. This is only a problem at dawn, dusk, heavy overcast, and in the woods.<\/p>\n
If you primarily use binoculars for watching ducks, hawks, and seabirds then 10x can be better. Or if you live in prairie or grassland and don’t do much forest birding, then they may be preferable. Long-distance viewing in open country favors more magnification.<\/p>\n
If you want more than 10x magnification then you want to buy a spotting scope on a tripod.<\/p>\n
The best birding binoculars have exit pupil of 5 or greater<\/h3>\n The exit pupil spec is an indication of brightness due to lens size. It is the ratio of objective lens (the “big end”) size (in millimeters) to magnification. Thus 7×35, 8×40, and 10×50 all have an exit pupil of 5.0. The popular 8×42 has an exit pupil of 5.25 so gives an even brighter image in low light conditions.<\/p>\n
Compact binoculars have smaller objective lenses. They are smaller in size and lighter weight. But 8×24 is an exit pupil of 3.0 and an 8×32 is an exit pupil of 4.0. A popular 10×42 is an exit pupil of 4.2–better, but still not as bright as the 8×42.<\/p>\n
Again, you notice this in dim early light, in the woods, or under cloudy skies. You will not see the difference on a bright sunny day or in the store.<\/p>\n
The best Schmidt-Pechan roof prism binoculars are made with BaK-4 prisms and have phase coatings and dielectric mirrored surfaces<\/h3>\n The most popular style of roof prism binoculars is made with Schmidt-Pechan<\/b> style of prisms. Unfortunately, because of the index of refraction, they require adding mirror coatings to the prisms. In the past, aluminum or silver mirror coatings were used. This causes a loss of brightness as some of the light bounces around inside the binoculars and doesn’t come out to your eyes.<\/p>\n
The best prisms today are BaK-4<\/b>. The best coating for these prisms are dielectric coatings<\/b>. With this combination, most of the light entering the binoculars comes out to your eyes. This creates a nice bright image.<\/p>\n
Roof prism binoculars with Abbe-Koenig<\/b> style prisms do not lose light on the mirrors, so don’t require any coatings<\/b>. This style is available on some high-end binoculars. They are longer than other binoculars, have larger objective lenses, and are very expensive. They typically come in 8×56 and 10×56 models, which are primarily for wildlife observation at twilight. They might be good for owls, but not general bird watching.<\/p>\n
The light path through the prisms on roof prism binoculars cross over each other. This can cause interference with the colors. Phase coatings<\/b> on the prisms give bright and accurate colors.<\/p>\n
The best birding binoculars all have BaK-4 prisms with dielectric and phase coatings<\/b>. That is, unless you have the Abbe-Koenig style, which doesn’t need them.<\/p>\nThe lenses on the best binoculars are made of Extra-Low Dispersion (ED) Glass<\/h3>\n
What happens when white light goes through a prism? It breaks into a rainbow of colors. To a lesser degree this happens with lenses, too.<\/p>\n
If nothing is done to correct it, you may notice a purple fringe or perhaps a yellow-green fringe around high contrast objects. This is called chromatic aberrations.<\/p>\n
For instance, if you look at an electric wire against the bright sky, you may notice this chromatic aberration on the edges of the wire. This is especially true at the very edges of your binocular field of view. ED glass virtually eliminates this phenomenon, edge-to-edge.<\/p>\n
You want your birding binoculars to have ED glass.<\/p>\n
The best binoculars have all glass-to-air surfaces fully multi-coated<\/h3>\n Anti-reflective lens coatings reduce light reflections off the glass. More light goes through the binoculars. The image is clear and bright, even in dim light conditions.<\/p>\n
Not just coated, multi-coated.<\/p>\n
Not just some surfaces, fully multi-coated<\/b>.<\/p>\nThe best binoculars have long eye relief<\/h3>\n
Long eye relief is necessary if you use eyeglasses with binoculars.<\/p>\n
If you don’t wear eyeglasses (yet) then you extend the eyecups, pushing your eyes farther from the eyepiece lenses. If you wear eyeglasses then you push the eyecups in, shortening them. Your glasses are already making a larger gap between your pupils and the eyepiece lenses.<\/p>\n
The best binoculars have eyecups that twist in and out with multiple stops, and don’t accidentally move easily. Cheaper binoculars have fold-down rubber eyecups.<\/p>\n
Eye relief is measured in millimeters. Choose binoculars with eye relief of at least 17 millimeters. Otherwise, with eyeglasses, you will not see the entire field of view. The binocular image will vignette. That is, the edges of the image will fade to black prematurely, less than what it should be.<\/p>\n
Eye relief less than 15.5 mm is not suitable for eyeglass wearers. At all. This is a problem for many compact binoculars.<\/p>\n
Longer eye relief is better, 17-20 mm is ideal.<\/p>\n
The best binoculars for bird watching focus very closely<\/h3>\n The close focus specification tells you how closely the binoculars focus.<\/p>\n
Birding binoculars should focus to at least 8-10 feet. That way you don’t have to back up to view a bird near you in a bush. Close focus binoculars will allow you to view hummingbirds out the window without backing into the next room.<\/p>\n
If you also want to view butterflies in a puddle at your feet, you want close focus of 5-6 feet, or less.<\/p>\n
The best birding binoculars have a very wide field of view (FOV)<\/h3>\n For me, this is one of the most important specs on a bird watching binocular.<\/p>\n
A wide field of view gives a picture-window panorama, not a view through a straw.<\/p>\n
A wide field of view on an 8x binocular is over 390 feet @ 1000 yards. For 10x binoculars that is reduced to 360 feet minimum.<\/p>\n
A wide field of view allows you to quickly find a bird when you raise your binoculars. No searching around this way and that looking for it.<\/p>\n
Another advantage of the wide view is to notice birds adjacent to the one you are observing. You’ll be able to observe more of the bird’s interactions with other birds or the environment.<\/p>\n
Following warblers hopping through the tree tops with binoculars can be frustrating. They keep jumping out of view and you have to find them again. This trouble is reduced by having a wide field of view. Even if they fly-hop 3 to 5 feet you are still able to follow them, because they never leave the image view.<\/p>\n Bird watching by diane-helentjaris<\/figcaption><\/figure>\nThe best bird watching binoculars are waterproof and fog proof.<\/h3>\n Birding binoculars must be available to use in the worst weather. If it rains, you must not be concerned that your binoculars will get water in them.<\/p>\n
And don’t be concerned if you place your binoculars in the bottom of the boat. Waterproof binoculars should be able to stay in water up to 3 feet deep for at least 10 minutes. I wouldn’t recommend it, but it gives you peace of mind knowing that you could swamp your boat and the binoculars would not be ruined.<\/p>\n
Waterproof binoculars can even be rinsed off in the sink after a salty day on the beach. Just don’t run a strong stream of water that may force its way in. Better to just use a damp rag, to be safe.<\/p>\n
Such binoculars are sealed against water. But they also are filled with dry nitrogen or argon gas. This prevents any fogging on the inside of the binoculars, when going from hot to cold.<\/p>\n
The best binoculars have a lifetime no-fault warranty<\/h3>\n The more expensive binoculars have better warranties.<\/p>\n
All binoculars come with a warranty against manufacturing defects of at least a year. But as the price increases, you may find that your binocular will be repaired or replaced for free as the result of any accident.<\/p>\n
As long as your binoculars aren’t lost or stolen these better warranties apply.<\/p>\n
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