Birds & Binoculars

You can’t enjoy one without the other.

By William J. Cook ~ Photos By Marta Morton

It’s a tern convention on the dock! This one is largely attended by Sandwich Terns (distinguished by their long bills with a yellow tip) and one lone Royal Tern with the orange bill.

Few places in the world offer the birding paradise that can be found in the Turks & Caicos Islands, and there are many vantage points from which to take in these wondrous, diverse and colorful creatures. Sadly, it’s not uncommon for tourists to travel thousands of miles to add to their life lists only to use binoculars lacking in the clarity that would take a pleasurable adventure to a whole new level. Most of the anomalies causing that lack of clarity are thought to be related to the binocular but are actually due to poor collimation (misalignment) or the observer’s physiology.

Optics is a nebulous subject that many people leave to the ever-changing opinions found in magazines and on Internet binocular forums. Therein, when the topic moves to the more clinical side of things, collimation and physiology for example, opinions of the ultracrepidarians can range from inaccurate, through silly, to damaging.

I’ve spent 45 years in precision optics. First as a Chief Opticalman with the US Navy, as a civilian optical consultant, and finally as creator and manager of the Precision Instruments & Optics department for Seattle’s 123-year old Captain’s Nautical Supplies, where I was on the front lines of working with binocular shoppers and where I repaired and collimated more than 12,000 binoculars. 

Starting in the early 1990s, as a result of trying to add a touch of reality to the vastly misleading “auto-focus” craze that so many honest people bought into, I started writing to take on the false notions that were taking observers down so many of the costly and non-productive roads leading to fableland. 

Following, I’ll correct some of the biggest misconceptions that have befuddled observers for years and end by addressing one of today’s biggest problems in achieving a crisp focus. It’s a totally avoidable problem that rests with the observer and not the binocular. 

Auto-focus binoculars?

This sales ploy reached its peak in the 1990s but still haunts the observer looking for that something special and doesn’t mind trying to outsmart logic and physics to do so.

Regardless of what you have heard, read or think, you have seen for yourself there are no non-electronic auto-focus binoculars. Minolta once marketed a binocular that focused on the same principle as a modern digital camera, but having numerous deficiencies it wasn’t on the market long. 

Years ago, I made a bent-nail puzzle and gave it to a friend to tinker with while we talked. Figuring it out in short order, I grabbed the puzzle, turned my back, put it back together, and gave it to him again saying, “Okay, hotdog, let’s see you get this one apart as fast; I put it together backwards.” Although we continued talking for quite a while, he couldn’t figure it out. 

The puzzle only worked one way. Thus, it couldn’t have been put together “backwards.” Yet, the power of suggestion caused him to flounder. And that’s just what the auto-focus craze was based on. Good advertising need not be accurate or even meaningful; it has only to be believed.

Order in focusing

This Bananaquit appears to have enjoyed quite a feast of pomegranate seeds. They are locally called the “Chickadewilly,” a term that is often applied to all small birds.

Center-focus binoculars must be focused as they were designed to be focused and, in the vast majority of cases, the left telescope is to be focused first. For good imagery it’s not optional. 

A customer once told me her optometrist said she should always focus her right eye first because she was right-eye dominant. Consequently, based on his “expert” advice, she had spent years using her expensive Leica binocular to produce images of lower quality than expected of a $69 drugstore special, all the while believing something was wrong with her eyes. 

Why was following this optometrist’s advice wrong? Let’s start by following his instructions, focusing the right eye as directed, to find out. Bingo, your right eye is seeing a great image. But now, with the right eye sharply focused, you turn the center focus wheel or flip lever to focus your left eye. Since, however, there’s a 2-diopter difference (for example) in your eyes, and since the center focus wheel or lever was designed to focus both sides at the same time, sharply focusing your left eye has just defocused your right eye by 2 diopters. Something isn’t right. But you did what your optometrist told you to do. So, it must be you . . . right?  

When both eyes are sharply focused on the target, having followed the correct procedure, you may return to the center-focus wheel for focusing at various distances until the focus is altered by another observer or until one of the adjustments has been inadvertently reset. In doing so, you will maintain the dioptric difference between your eyes regardless of the distance to the target—500 feet or 5,000,000,000 miles. (Only 2 to 3% of the population have the same setting in each eye.)

Spatial accommodation

The Brown Pelican is a common sight in the TCI, and although this one seems surprised, it is more likely coming in for a landing.

Spatial accommodation is a collimation (alignment) issue that, more often than not, originates with the binocular but which can be caused by the binocular’s IPD (interpupillary distance) to be misplaced relative to the separation of the user’s eyes. 

For example, just placing a binocular to the eyes is inadequate unless positioned in such a way that the binocular’s exit pupil is placed precisely in front of the pupils of the observer’s eyes. If the observer has an IPD of 69 millimeters and the binocular’s IPD is set to match, all is well. If not, the observer must use some degree of eye-straining spatial accommodating, even if the binocular is well collimated.

The Internet is replete with articles telling observers how they can “easily” correct misalignment by tweaking a few through-the-body/prism-tilt screws, with most such instructions omitting other alignment conventions and the repairs often needed to allow any of those conventions to work.

There are, however, stipulations of which the exuberant screw-tweaker needs to be aware. IF only one side of the binocular is misaligned, IF that side is the one adjusted, IF the error is small, IF the individual’s physiological accommodation is adequate, and IF the distance to the desired target is far enough this—conditional alignment—may be enough to make the instrument perform well or even excellently. Even so, while that is adequate for some users, it leaves others, who didn’t have all those IFs in their favor, frustrated with a less than crisp image. 

In addition, without specific knowledge, the same procedure can push the binocular ever farther out of alignment and can, in some cases, damage the instrument. And although rarely, if ever, seen in print, understanding spatial accommodation is critical to getting the best view from the binocular.

So, if you find that your binocular gives you a double—or even an uncomfortable—image you should consider that the binocular may be misaligned or you don’t have the telescopes spaced properly for your eyes. In order to find out, bring the binocular to your eyes and seek the best view of a target at least a mile away. A streetlamp will work fine. Then slowly move the instrument 8 to 10 inches away from your face. Try to just stare. If the error is small, your brain will compensate. If problematic, alternate the opening and closing of each eye. Is the image still, or does it dance? If the latter, you have a collimation issue and with the lack of qualified binocular techs around, the instrument should be replaced by the vendor or repaired at the factory. 

Dioptric accommodation

The female Bahama Woodstar hummingbird builds her tiny nest from bits of plants and spider silk, cemented with her saliva. In it she lays two eggs; the resulting chicks shown here are quite grown and nearly ready to leave the nest!

This is an anomaly of your own physiology, something that affects almost every observer, and is something you control.

Frequently, an observer will focus on a target quickly and expect the instrument to remain focused—at least at the given distance. However, let’s say you have a dioptric accommodation range of 4 diopters and stop focusing the instant you have an adequate image. As time goes on, observing may become problematic because your natural (relaxed at that distance) focus setting should be –1.5 diopters. That means being in a hurry has placed your focus at an accommodatable, but strained, setting. 

Then, as fatigue sets in, you may fiddle unnecessarily with the focus or suppose there’s something wrong with your eyes or the binocular when neither is true. In addition, as this “fiddling” takes place, the observer will more than likely repeat the hurried technique that got him into trouble in the first place, leaving him or her once again with an imprecise focus. Perhaps your mother taught you never to stare. Nevertheless, if you want a crisp image, you had better forget that advice.

Dioptric accommodation (the ability to focus at a range of distances) is achieved through the eye’s ciliary muscles, which stretch and compress the eyelenses in order to achieve a sharp focus. A 10-year old may have as much as 14 diopters of accommodation. But as we age, dioptric flexibility drops off fairly quickly. By age 20, it has dropped to 8 to 10 diopters with the average binocular user—40 to 50 years of age—having only a 4-diopter accommodation. Thus, with each year that passes—up to about 60—the focus mechanism becomes ever more critical. 

Learning to stare comes easily for some people but takes a great deal of practice for others. But learning to stare, letting the binocular’s focus come to you, is worth the effort and is absolutely essential to attaining the sharpest image, most trouble-free focus, and the clearest views of the nature around you.

Happy and productive birding!


Birding in the Turks & Caicos Islands

Quiet ponds and salinas scattered across the Turks & Caicos Islands are an excellent place to spot waterbirds.

Bird-watching (these days known as birding), is a recreational activity for millions of birders worldwide. It can be done with the naked eye, through binoculars and telescopes, by listening for bird sounds or by watching public webcams. Many birders maintain a life list of all the species they have seen, usually with details about the sighting such as date and location. Birding ecotourism is popular because birders typically have a lighter footprint from not wanting to disturb the birds and are often pioneers for furthering conservation projects to protect the habitats of wild and rare bird species.

According to TCI Naturalist and Terrestrial Ecologist for the TCI Department of Environment and Coastal Resources B Naqqi Manco, the top three locations here for birders are as follows:

• On Providenciales: Provo Golf Course, Cheshire Hall Creek (late afternoon into dusk) and Wheeland Ponds. 

• On North and Middle Caicos: Village Pond, Middle Caicos; Wade’s Green Plantation, North Caicos; Flamingo Pond, North Caicos. 

• On Grand Turk: Town and Great Salinas, North Wells and Red Salina. 

What should birders look for? Manco expands, “Reddish egrets are rare globally but common in TCI. Cuban crows can only be seen in the Caicos Islands outside of Cuba. TCI has an endemic subspecies of thick-billed vireo, which is common throughout, and one of Greater Antillean bullfinch restricted only to Middle and East Caicos. White-tailed tropicbirds are seasonal visitors to seaside cliffs in summer. Black-necked stilts are common in ponds and are both easily identified and photogenic. Caribbean flamingoes are always a favourite and are easily viewed in great numbers on North Caicos and at close range on Grand Turk.”

“In the winter months, migratory birds may be seen on the ponds of the Provo Golf Course, Wheeland Ponds on Providenciales, and at the Wade’s Green Plantation high forest on North Caicos.”

“Seabird cays such as French Cay, Bush Cay and the Southern Cays; and Long Cay off Grand Turk are sanctuaries and landing is prohibited without a permit. Thus, summer seabird observations must be done from boats.”

“North and Middle Caicos are worth a visit for potential life-listers including Key West quail-dove, pearly-eyed thrasher, white-tailed tropicbird, Greater Antillean bullfinch, thick-billed vireo, white-crowned pigeon, smooth-billed ani, mangrove cuckoo, Bahama mockingbird, and Cuban crow. Large migratory flocks move through North and Middle Caicos quickly in September and October and include bobolinks, blue grosbeaks, and indigo buntings. Summer breeding residents to these islands absent in winter include Antillean nighthawks and gray kingbirds.”

“The salinas on Grand Turk are especially good for photography as Caribbean flamingoes, brown pelicans, snowy egrets, reddish egrets, tricolor herons, little blue herons, black-necked stilts, and several species of sandpipers are there unafraid of people and very approachable. Magnificent frigatebirds are often seen over the Grand Turk salinas.”

There is a series of booklets entitled, “Birding in Paradise” targeted to the individual islands, and they include suggested tour routes, bird lists, and information on other flora and fauna and history. They are available through the Turks & Caicos National Museum Foundation or on the website www.ukotcf.org.uk. Another good source is The Birds of the Turks & Caicos Islands by Richard Ground. It is sold in local bookstores and shops.

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