The Binocular Site
A Parent’s Guide to Choosing Binoculars for Children
With all the attention now being given to the importance of getting kids outdoors, many parents are increasingly interested in involving their children in one of the variety of outdoor activities that require a binocular for full participation.
Whether that activity is bird watching, nature study, hunting, or any of the other many possibilities, the selection of the right binocular for use by the child is of great importance. However as most binoculars are designed for use by adults, selecting one for use by a child is not always an easy task. What follows are intended to be a few things to consider and keep in mind when making the selection.
Interpupillary distance (the distance measured between the exit pupils of the binocular eyepiece – or ocular – lenses; also the distance measured between the pupils of the eyes of the binocular user) is by far the most important factor in determining whether a binocular is suitable for a child. If the interpupillary distance of the binocular – measured as the minimum and maximum distances to which the two halves of the binocular can be adjusted using the central hinge or hinges – does not allow for adjustment to the specific distance required by the user, part or all of the image seen through one or both halves of the binocular will be obscured by a dark shadow.
Children, particularly those under ten years of age, typically have interpupillary distance measurements of between 53 – 57mm and even as low as 50mm. As the majority of binoculars on the market today still have interpupillary distance ranges of between 60 – 70mm, the incompatibility becomes quite clear.
While some binocular manufacturers clearly indicate the interpupillary distance (sometimes abbreviated as IPD) of all their binocular models, many still leave this information out of their advertised specifications. However even when a binocular’s IPD is available for the customer to consult, unless the intended user of the binocular wears eyeglasses, for which the measurement of this distance is required for fitting, the user’s own interpupillary distance will not likely be known.
A visit to an optometrist will allow the user’s interpupillary distance to be measured for use in determining compatibility with binoculars for which the IPD is known. Binoculars for which this information is not published can only be checked for compatibility by allowing the intended user to try them personally.
Another challenge to selecting a binocular for use by a child is the ability of the child to hold and operate the binocular in a comfortable manner. In days gone by, when large and bulky binoculars were the norm, this was often a major obstacle; however, thanks to advances in optical design and lens coating technology, as well as demand by the binocular buying public, smaller binoculars are now far more common. Yet this does not mean that just because a binocular is easy to hold by an adult that it will also be the same in the hands of a child.
While weight and relative bulk can sometimes be a problem even in a smaller-frame binocular, a greater challenge is more commonly the inability of a child to reach and operate the binocular. If the center focus dial cannot be comfortably reached with (generally) the index or middle finger without the child needing to reposition his or her grip on the binocular itself, then that binocular is not the right one for that child. Of course, the child may “grow into it;” however if faced with a binocular is not able to be effectively used, the benefit of using one is quickly diminished in the child’s mind and interest in using it will likely be lost by the time sufficient growth has occurred for its comfortable use.
In order to eliminate the need for perfect comfort in reaching the binocular’s center focus dial, some have advocated the use of independent focus or even “perma-focus” binoculars for children. There are three strong arguments against this. First, with the exception of the traditional 7x50mm maritime usage models, these types of binoculars are becoming very rare in the marketplace.
Second, setting them for use by a child is very challenging and with younger children not even always possible due to the subjectivity involved in making the adjustments to each half of the binocular independently.
Third, and perhaps most important, their “one-time focus” settings for all distances require the eyes of the user to accommodate the lack of clear focus in situations where the object viewed is either too close or too distant for proper focus to be offered by the binocular’s optical system alone. While a child’s eyes can often be very accommodating, it puts considerable and unneeded stress upon them that may pose ophthalmologic problems for them in the future.
If a binocular is found to be compatible to a child’s interpupillary distance, and can be comfortably held and operated by the child, the selection of magnification level is the next important decision to be made. Here a very important thing to remember is the experience level of the person to be using the binocular. Most children do not possess much experience using a binocular. In this, they share the very same challenge as adults who are just beginning to use a binocular: difficulty locating an object within the binocular’s field of view.
The image offered by a binocular to the user brackets off much of the view seen by the unaided eyes of the user in exchange for magnifying that portion of the unaided view that is seen through the binocular. The area seen through the binocular, called the “field of view,” is determined by many factors but is most commonly directly related to the magnification level of the binocular. Higher magnification level binoculars generally offer a more limited field of view than lower magnification level binoculars. In the same series of a particular binocular manufacturer’s product line, this balance will be a nearly universal truth.
What does this mean to an inexperienced binocular user? Quite simply that a lower magnification level binocular will allow a greater portion of the unaided view to be seen when viewing through the binocular and consequently things the user desires to view will be easier to locate in the field of view.
While some may object that lowering the magnification level of a binocular reduces its effectiveness, it should be remembered that lowering the magnification level of a binocular, all other things in its design being equal, allows the binocular to offer the user an image that is brighter, possessing a greater depth of field (how much of what is seen being simultaneously held in focus at any given focus setting), and less prone to “shake” due to movement by the user.
How low is “lower” in terms of magnification? While most binoculars commonly sold today are offered in 8x or 10x models, “lower” implies something between 5x and 7x. In order to keep the exit pupil of the binocular to a proper size for comfortable use, make sure the diameter of the objective lens is at least three times and preferably at least four times the magnification level. While this does limit the number of potential models available, the benefits make the additional effort to locate them well worth it.
It should be noted that this advice on the benefits of lower magnification level binoculars is also advice that adults would do well to heed in selecting binoculars for their own use, particularly if they have any number of eyesight problems, including uncorrected cataracts and macular degeneration that make using a higher magnification level binocular problematic.
As the primary considerations to be made in selecting a binocular for children have now been covered, there are two items to be remembered in order to avoid them. First, don’t buy a toy binocular for anything other than a toy. If a child is to be given a binocular to use in the same way as an adult would use one – for bird watching, nature study, hunting (with older and more experienced hunters of course) – then they deserve the same basic features in that binocular. These features include glass lenses, a prism-based optical system, proper optical alignment, etc. Toy binoculars offer none of these things and should be avoided accordingly.
Second, compact binoculars are not recommended for children. The optical parameters of compact binoculars, particularly the size of the exit pupil, make them less than ideal of extended periods of use. Compacts can be remarkably handy and are great for a wide variety of uses; however few adults would ever employ one as their primary field binocular and children should be given the same respect even though they themselves may not be the final decision makers as to the binocular selected for them.
With the items outlined above kept well in mind, the selection of a binocular for use by a child should be a fairly straight-forward process. It requires a little more “shopping around” than the selection of a binocular for use by an adult; however the results are well worth it. As the old saying goes, nothing you do for the benefit of a child is ever wasted.
This article was written for The Binocular Site by John E. Riutta. To learn more about John please see his full biography.