Binoculars for Hawk Watching
By Mohonk Preserve Director of Conservation Science Elizabeth Long
and Mohonk Preserve Research Associate Zach Smith
Autumn is upon us and to many people that means bird migration. There is a subset of birders, hawkwatchers, who undertake migrations of their own to ridge tops, coastlines and peninsulas to witness the seasonal movements of birds of prey. To fully enjoy this phenomenon, the aspiring hawkwatcher needs a good binocular. Since there are a wide variety of binoculars available, choosing the right one can seem overwhelming. What follows are guidelines to help narrow the choices to binoculars that will perform well and not break the bank. Binocular choice largely comes down to personal preference and what is comfortable. YOU are the only one using your binocular day in and day out, so it has to work for YOU.
The main factors to consider:
1. Roof vs. Porro Prism
3. Magnification and Aperture
4. Field of View (FOV)
Roof Prism vs. Porro Prism
You can tell these two styles apart by looking at the shape of the barrels. Roof prism binoculars will have two barrels that are straight and parallel to each other. Porro prism binoculars will have a jog in the barrel.
Go with roof prism. They are more durable, weatherproof and more comfortable in your hands. More detail here.
Don’t bother with compact binoculars for birding/hawkwatching. Period. Unfortunately there are very few models of compact binoculars that have high quality optics, and most of these are designed for very close focus. If you are interested in using binoculars for looking at insects there are some decent compact models, but for birdwatching you will quickly outgrow them if you become serious about the activity.
Magnification and Aperture
The two numbers separated by an “x” tell you the magnification and aperture size. A 7x42 binocular has 7x magnification and an aperture (objective lens) diameter of 42 millimeters (mm). Higher magnification means the object looks closer, but the image is harder to keep steady. The aperture basically indicates how much light is entering the binocular. Larger diameter = more light. Don’t be tempted by a really large diameter, like 50 mm. These binoculars are large, heavy and more difficult to hold steady.
The relationship between these two numbers is an important factor to consider. Dividing the aperture diameter by the magnification yields the exit pupil. The exit pupil for a 8x42 binocular is 42/8 = 5.25 mm. This is the diameter of the shaft of light that exits the binocular and enters your eye. Hold the binocular a foot or so away from your eyes. The hole of light you see is the exit pupil. A larger exit pupil = more light gathered and a brighter image. An exit pupil of at least 4mm is considered the minimum for any type of bird watching. A nice description on the importance of a large exit pupil, with video and diagrams, can be found here.
Common sizes you will see around the necks of birders are 7x42, 8x42 and 10x42. All are good for hawkwatching.
Field of View
This is the diameter of your view at 1,000 yards. A wider FOV = a better chance of finding a bird when you look through the binocular. A higher magnification usually = narrower FOV. A typical FOV is in the 300–400 foot range. A few models have 400+ ft. FOVs. There is usually a tradeoff between FOV and magnification. See this link for an FOV diagram.
Don’t consider a binocular that is not waterproof and fogproff. Moisture inside a binocular is bad.
Hawkwatching requires a lot of holding your binocular to your eyes. Heavier = arms tire more quickly. Most 7–10x binoculars fall between 20–28 ounces. Look for something in this range.
Advice for the novice — don’t even look through a top-end binocular at this point. That way lies madness! You won’t have had time to decide what you like and what is most important to you until you have been at it for a while, so there’s not point investing a ton of money into something you may not like. Stick to the $250-$500 range. Unless you are a serious birder or professional field ornithologist, a top-end binocular is unnecessary for your first purchase. This probably means avoiding The Big Three — Leica, Zeiss and Swarovski. Most of the binoculars they offer go for north of $1500 and are amazing. However, keep these names in the back of your mind for the day when you realize “I am a serious birder.” This may happen sooner than you think! At the same time, though, realize that binoculars are expensive and you’ll definitely be happier with a $300 pair than a cheapo model from a big box store!
Here is a short list of excellent, modestly-priced binoculars that perform well for birding and hawkwatching.
1. Zeiss Terra. Yes, one of The Big Three, but under $500. FOV=375 ft. (8x42). 25 oz. 10x42 available.
2. Eagle Optics Ranger. Under $350. FOV=315 ft. FOV (8x42). 22 oz. 10x42 available.
3. Nikon Monarch. Under $300. Excellent FOV=420 ft. (8x42). Light weight ~21 oz. 10x42 available
4. Vortex Viper. Under $500. FOV=347 ft. (8x42). 24 oz. 10x42 available
To summarize, look for a binocular with the following features:
1. Roof prism
2. Standard, not Compact
3. Magnification/Aperture between 7x42 and 10x42
4. FOV over ~320 ft at 1,000 yards
5. Waterproof and Fogproof
6. Weight between 20–30 ounces
7. Price between $250 — $500
If possible, try many different models. Hold them, walk around with them, play with the focus knob and eyecups. Compare the features mentioned in this article. Look at bright objects and dark ones. Come to your own conclusions about what you like and don’t like. Talk to birders about their binoculars. Believe me, most birders LOVE to talk about binoculars, have at least one gripe about theirs and are generally helpful to novices because they were novices at one time. This is a great way to pick up tips on binocular use for birding.
Click here to learn more about HawkWatch and other Citizen Science programs at Mohonk Preserve.