The Binocular Site
Binoculars and Eyeglasses – Compatibility is Possible
Ask anyone who wears eyeglasses how they like them and they’ll likely say they’re a mixed blessing. While eyeglasses allow for those with nearsightedness, farsightedness, and a variety of other optical difficulties to see the world around them clearly, they also have drawbacks.
Eyeglasses fog in cold weather. Rain, mist, dust, and pollen collect on them easily, requiring frequent cleaning. Lenses can be scratched, chipped, or broken. And for those who participate in any activity that involves the use of binoculars, they bring an assortment of additional challenges. But with a little understanding and forethought, those who wear eyeglasses can overcome the challenges of binocular use.
The primary difficulty faced by those who wear eyeglasses when using binoculars is caused by the binoculars’ eye relief. This is the distance required between the eyepiece lenses of the binoculars and the user’s eyes for a full image field to be seen. In many cases, it’s too short to accommodate eyeglasses. Modern binoculars, depending on the design and level of magnification, commonly have eye relief measurements between 12mm to 20mm.
The user’s eyes must be positioned at the binocular model’s specific eye relief distance for the full image field to be seen. Without eyeglasses, this can be accomplished by bringing the binocular eyepiece lenses close to the user’s eyes. But when eyeglasses are worn, a certain amount of space is “protected” between the user’s eyes and the eyeglass lenses. Depending on the style of eyeglasses worn and the thickness of the lenses, this distance can sometimes be larger than the binoculars’ eye relief, so wearing eyeglasses will not be ideal when using the binoculars. For this reason, anyone who must wear eyeglasses while using binoculars should pay attention to the type of eyecups the binoculars have.
To make positioning the eyes behind the eyepiece lenses easier, and to block out glare caused by light shining onto the eyepiece lenses from the side, most binocular models have plastic or rubber eyecups encircling their eyepiece lenses. Not so long ago, most of these eyecups were made of hard plastic or metal, and were not adjustable. These old eyecup designs, combined with the tendency of binocular designers to use very small diameter eyepiece lenses, made most binoculars all but impossible to use while wearing eyeglasses.
Fortunately, times and binocular eyepiece designs have changed. Recent models commonly feature either soft rubber eyecups that can be folded down as needed or, even better, adjustable eyecups that can be extended or retracted by twisting or pulling / pushing to offer the user just the right depth between the rim of the eyecup and the binoculars’ eyepiece lenses.
For the best compatibility, binoculars to be used while wearing eyeglasses should allow the eyecups to be folded, twisted, or pushed down completely to offer only the barest of margins of protective eyecup material forming a ring just above the highest point of the eyepiece lenses. If this can be achieved by the binoculars’ eyecups, and if the binoculars’ eye relief distance is sufficient, the binocular can be brought right up to the user’s eyeglass lenses, and the binoculars’ full image field can be clearly seen. How can you tell if it’s not? Simple – there will be a shifting black shadow that produces a tunnel-vision type of effect when looking through the binoculars.
Now, the reasonable question is, “Why not avoid this difficulty altogether and simply remove your eyeglasses when you want to use binoculars?” First of all, because it’s cumbersome to take off eyeglasses and find a place to safely hold or stow them while getting binoculars into position and focused on an object in the field. Even worse, for situations requiring rapid viewing – such as in birdwatching – the extra time needed to do so slows down the ability to get the desired object in view quickly, and increases the likelihood of dropping the eyeglasses in the process.
Then there is also the matter of why eyeglasses are worn in the first place – to correct vision problems. By the use of their diopter adjustment mechanism, binoculars do allow for a certain amount of accommodation to be made when the respective visual strengths of a user’s eyes are different. But the amount of diopter correction is limited, and it alone cannot correct all the other visual problems for which eyeglasses are worn.
In addition, many visual problems, especially uncorrected cataracts, are made worse from the user’s perspective when using a magnified optic such as binoculars. With that in mind, it can be easily understood why one would want to wear eyeglasses when using binoculars. Without the eyeglasses, the image seen through the binoculars could be of far lower quality than desired.
In most cases, the eyeglasses a person wears are a matter of personal choice and individual style. But if the wearer knows they are going to be worn while using binoculars, it’s preferable to select a frame style that will position the lenses reasonably close to the face. This will allow the user to choose from a wider selection of binoculars. In some cases, it might be better to wear contact lenses to correct any vision problems.
But contact lenses have their own difficulties, and not everyone is comfortable wearing them, especially when they are only worn occasionally. If a person normally wears eyeglasses, it is best to find binoculars compatible with them rather than go to the trouble of getting contact lenses.
When selecting eyeglass-friendly binoculars, beyond paying attention to how the eyecups function and whether they can be properly positioned, look for models with an eye relief distance of at least 16mm. While this distance will not necessarily accommodate all eyeglass styles, it will be compatible with the majority of them. Magnification is also something to consider.
Binoculars with lower magnification levels tend to have longer eye relief distances, as well as more eye relief forgiveness—the area surrounding the position of optimal eye relief in which the full image field can still be seen. Magnification levels of up to 8x with a corresponding 4mm minimum exit pupil diameter—the diameter of one objective lens divided by the level of magnification—are most likely to be compatible with eyeglasses. Higher magnification level models tend to have shorter and less forgiving eye relief.
To help those in the market for eyeglass-friendly binoculars, here are a few suggestions of models known to be compatible with eyeglasses:
The Bushnell 8x42mm Elite E2 roof prism binocular – European-style eyecups recess flat and offer a very close eyepiece lens to eyeglass lens distance.
The Leupold Katmai 6x32mm and 8x32mm roof prism binoculars – Generous and forgiving eye relief, multi-position padded twist-up eyecups, and large eyepiece lenses make either of these outstanding binoculars for eyeglass wearers.
The Minox HG 8.5x43mm BR roof prism binoculars – In addition to twist-up eyecups that lay flat, and a generous amount of eye relief, Minox incorporates ashperical lenses into their design for a more even center-to-edge image that is particularly beneficial to those wearing eyeglasses.
The Nikon 8x32mm and 8x42mm Premier roof prism binoculars – Exceptionally long eye relief coupled with very large eyepiece lenses make these two Nikon binoculars remarkably eyeglass-friendly.
And for those willing to go all out:
The Leica 7x42mm Ultravid HD roof prism binocular – All the requirements needed for eyeglass compatibility, plus the benefits of the generous exit pupil diameter, and overall performance of the legendary 7x42mm optical design.
The Swarovski 8.5x42mm EL roof prism binocular – Not only do the European-designed eyecups retract fully into the binocular chassis, the exceptionally large eyepiece lenses combine with the overall optical design to produce binoculars that are not only eyeglass friendly, but fast on the target while wearing them or not.
The Zeiss Victory FL 7x42mm roof prism binocular – Offering one of the widest field of view measurements of any full size binocular on the market today, the Zeiss Victory FL offers those wearing eyeglasses a fully compatible fast and light binocular for almost any field application.
This article was written for The Binocular Site by John E. Riutta. To learn more about John please see his full biography.